Primary Chest WallTumors

Shona E. Smith, MD, FRCSCa,Shaf Keshavjee, MD, MSc, FRCSCa,b,*

KEYWORDS

� Chest wall tumors � Chest wall sarcoma � Ewing sarcoma� Chondrosarcoma � Osteosarcoma

INTRODUCTION

Patients with chest wall tumors present diagnosticand therapeutic challenges. The differential diag-nosis of these tumors is broad, because they canrepresent a heterogeneous spectrum of diseasesfrom primary benign or malignant tumors tometastases; local extension of adjacent tumorsof the lung, mediastinum, pleura or breast; non-neoplastic infectious or inflammatory conditions;or even local manifestations of systemic disease.Primary chest wall tumors are best classified ac-cording to their tissue of origin, bone or soft tissue,and further subclassified according to whether ornot they are benign or malignant. Most of thesetumors are uncommon, with information garneredfrom individual case reports or institutional caseseries.

Chest wall tumors are more commonly eithermetastases or local invasion of an underlying adja-cent tumor. Primary chest wall tumors account foronly 0.04% of all new cancers diagnosed and 5%of all thoracic neoplasms.1 The list of potentialtumors is broad (Table 1), with nomenclaturethat is frequently overlapping and sometimescontradictory in the literature. Primary benignlesions of the chest wall can behave in a latent,active, or aggressive manner. Approximately60% of primary chest wall tumors are malignant.Although primary chest wall tumors are diagnosedin every age group, they are more likely malignantin the extremes of age: in the young and theelderly. Certain tumors present predominantly inone age group. For example, Ewing sarcoma is

a Division of Thoracic Surgery, University of Toronto, ToToronto, ON M5G 2C4, Canadab University Health Network, Toronto General Hospital,* Corresponding author. Division of Thoracic Surgery, UElizabeth Street, 9N955, Toronto, ON M5G 2C4, Canada.E-mail address: Shaf.Keshavjee@uhn.on.ca

Thorac Surg Clin 20 (2010) 495–507doi:10.1016/j.thorsurg.2010.07.0031547-4127/10/$ e see front matter � 2010 Elsevier Inc. Al

more common in children and young adults, prim-itive neuroectodermal tumor (PNET) in patients intheir 20s, and chondrosarcoma in middle adultlife and solitary plasmacytoma occurs morefrequently in older adults. Of malignant tumors,chondrosarcoma and lymphoma are most promi-nent in adults,2 whereas in children, Ewingsarcoma and rhabdomyosarcoma are the mostcommon tumors.3

DIAGNOSIS

Patients often present with a palpable enlargingmass. Less commonly, asymptomatic patientsare diagnosed due to an incidental finding onimaging as part of screening or for investigationof an unrelated condition. Soft tissue masses areoften painless, whereas bony lesions, both benignand malignant, are typically painful due to growthand periosteal damage. Symptoms develop asthe tumor grows and can be associated with localinvasion of adjacent structures. Paresthesias andweakness may be present if neurologic structures,such as the spinal cord or brachial plexus, areinvolved. Systemic symptoms of fever, malaise,fatigue, and weight loss in addition to suggestinginfection or metastasis, are also seen in eosino-philic granuloma and Ewing sarcoma. Due to therarity of chest wall tumors, the time between onsetof symptoms and diagnosis is often long.4 Rapidincrease in tumor size, involvement of surroundingtissues, and cortical destruction suggests malig-nancy, although they are not pathognomonic.Although clinicians often associate pain with

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Table 1Classification of primary chest wall tumors

Bone Tumors Benign Malignant

Bone OsteoblastomaOsteoid osteoma

Ewing sarcomaOsteosarcoma

Cartilage Chondroma (enchondroma)Osteochondroma

Chondrosarcoma

Fibrous tissue Fibrous dysplasia

Bone marrow Eosinophilic granuloma Solitary plasmacytoma

Osteoclast Aneurysmal bone cystGiant cell tumor (osteoclastoma)

Vascular HemangiomaCystic angiomatosis

Hemangiosarcoma

Other Mesenchymal hamartoma

Soft Tissue Tumors

Adipose tissue LipomaOssifying lipoma

Liposarcoma

Fibrous tissue Fibroma (desmoid tumor)Ossifying fibroma

FibrosarcomaMFH

Muscle LeiomyomaRhabdomyoma

LeiomyosarcomaRhabdomyosarcomaTendon sheath sarcoma

Nerve NeurofibromaSchwannoma (neurilemmoma or neurinoma)

Askin tumor (PNET)Malignant schwannomaNeurofibrosarcomaNeuroblastoma

Vascular HemangiomaVascular leiomyoma

Hemangiosarcoma

Other Hodgkin diseaseLeukemiaLymphomaLymphosarcomaMixed sarcomaReticulosarcoma

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malignant chest wall tumors, pain is not a reliablepredictor of malignancy. Similarly, fixation tounderlying tissues is not helpful in diagnosingmalignant lesions, because it can be found inboth malignant and benign conditions. There areno specific signs or symptoms that distinguishbetween benign and malignant lesions.4

Work-up should begin with a thorough historyand physical examination. Imaging should be in-terpreted based on the location of the lesion andits size, the lesion’s effect on the bone, the bone’sresponse to the tumor, characteristics andcomposition of the tumor’s matrix and cortex,and any evidence of a soft tissue mass.5 Usuallya chest radiograph is obtained first. Plain radio-graphs can demonstrate bony erosion of thelesion, lytic lesions, mediastinal lymphadenopathyor invasion, and the presence of any large pulmo-nary metastases. CT and MRI, however, are the

critical imaging modalities. A chest CT assessesthe extent of bone, soft tissue, pleural and medias-tinal involvement, and pulmonary metastases andhelps with surgical planning. It is more sensitivethan plain films for determining bony corticaldestruction or tumor matrix calcification.6 MRIfurther delineates soft tissue, vascular and nerveinvolvement, and the presence of spinal cord orepidural extension, which is particularly helpful indelineating anatomic relationships of tumors inthe thoracic inlet.7 In general, benign bony lesionsare small, with distinct geographic margins,whereas their malignant counterparts are perme-ative with bony destruction and show a sunburstpattern. Osteosarcomas and Ewing sarcomasmay also demonstrate elevation of the periosteumat the interface of the tumor as it expands, referredto as Codman triangle.8 Benign soft tissue tumorsare often small and superficial, and certain tumors

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have classic appearances on imaging. Malignanttumors are often deep to the fascia and appeardark on T1-weighted MRI images and bright onT2-weighted MRI images. Radionucleotide bonescanning is done to rule out bony metastases.

Although imaging characteristics can suggestdiagnosis of bony lesions, many soft tissue tumorsrequire tissue for diagnosis. Biopsy methodsinclude core needle as well as open incisionaland excisional biopsy techniques. Although coreneedle may allow differentiation between benignand malignant processes, it may not provide suffi-cient tissue for histopathologic subtyping orgenetic analysis. For lesions less than 2 cm,thought to be benign, and where primary closureis possible, excisional biopsy is recommended. Iflarger than 2 cm or suspicious for a primary malig-nancy, however, an incisional biopsy should bedone. Incisional biopsies should measurea minimum of 1 cm3 and be delivered fresh topathology to allow diagnosis while allowing latercomplete wide excision. Care should be takenwith the size and orientation of the biopsy becauseit must be completely incorporated in any futuredefinitive surgical excision. The lesion should beapproached directly to avoid contamination ofunaffected structures. The creation of flaps orextensive dissection is contraindicated. For non-palpable lesions, preoperative wire localization orinjection ofmethylene blue into the skin, soft tissue,and bone cortex can help localize the lesion.

LOCATIONPrimary Tumors of the Rib

Primary tumors of the rib comprise only 5% to 7%of all primary bone neoplasms9,10 but make up50% of bony malignant tumors and the majorityof benign bony tumors of the chest wall. Tumorsof the rib are derived from bone, cartilage, bonemarrow, vascular, or neural structures. Of thebenign lesions, fibrous dysplasia and chondromaare the most common, 9 whereas chondrosarcomaand osteosarcoma are the most common malig-nant rib lesions.11 Ewing sarcoma is the mostcommon malignant rib tumor in the pediatric pop-ulation.10 The location within the rib can help withthe diagnosis of the tumor. Chondromas and chon-drosarcomas occur anteriorly at the costochondraljunctions. PNET (Askin) tumors and hemangioper-icytomas occur posteriorly on the chest wall adja-cent to the vertebral column. In addition, size mayhelp predict malignant potential. In a 13-year retro-spective review at Children’s Hospital Boston of allpediatric rib lesions that were evaluated andtreated surgically, benign rib lesions were foundsignificantly smaller, with a mean diameter of

3.2 cm, compared with malignant lesions, witha mean diameter of 7.2 cm.10 Resection of malig-nant tumors should include wide resection of therib with 4- to 5-cm proximal and distal margins,resection of portions of the ribs above and belowthe tumor, as well as adjacent muscles and under-lying pleura and lung, if adherent.

Primary Tumors of the Clavicle and Scapula

Almost all bone lesions occurring in the skeletoncan occur in the clavicle, but none is common.Up to 30% of malignant bony chest wall tumorsoriginate in the scapula. Although uncommon,the benign soft tissue tumor classically found atthe inferior angle of the scapula deep to the serra-tus anterior muscle is elastofibroma dorsi. Elasto-fibroma dorsi tumors typically occur in elderlywomen, are slow growing, and have a right-sidedpredominance, although up to 66% are bilateral.12

Patients often present after developing symptoms,including pain and restriction of movement, and,although unclear, their pathogenesis may berelated to repetitive movement or trauma. TypicalMRI features include a sickle-shaped mass ofgenerally low signal intensity with areas of highsignal intensity on T1 and T2 images.13 Completesurgical resection is recommended if the diagnosisis unclear or if the patients are symptomatic.Pathology reveals a nonencapsulated fibrousmass with streaks of fat within the tissue. Therehave been no reported incidents of malignanttransformation of elastofibroma dorsi.12

Primary Tumors of the Sternum

Tumors of the sternum are usually malignant. Mostcommon primary tumors of the sternum are osteo-sarcomas and chondrosarcomas.1,14,15 In Chapel-ier and colleagues’16 case series of 38 patientsundergoing sternal resection and reconstructionfor primary tumors, approximately 50% werefound in previous irradiation fields. The size andlocation of the tumor determines the extent ofresection. Upper-third lesions require resection ofthe manubrium and sternal body as well as resec-tion of the medial ends of the clavicles and adja-cent sternocostal cartilages (Fig. 1). Any involvedadjacent structures, including lung, pericardium,or vessels, should be excised en bloc with thetumor. Middle-third lesions require resection ofthe sternal body, with preservation of the manu-brium and xiphoid, if possible4 (Fig. 2). Becausethese resections typically are extensive, theyrequire planning for both skeletal and soft tissuereconstruction, often with composite prostheses,such as Marlex methyl methacrylate (Fig. 3). Softtissue coverage to protect mediastinal structures

Fig. 1. (A) Visible anterior upper chest wall mass on physical examination; (B) CT chest demonstrating large softtissue inhomogenous mass with central necrosis eroding manubrium and proximal sternal body; and (C) resectionof mass including manubrium, proximal sternum, anterior first and second ribs, and medial ends of clavicles.

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is obtained with muscle or myocutaneous flaps,with the pectoralis major muscle most frequentlyused.15,16 Survival is related to sarcoma histologictype and grade.17,18 Wide resection, witha minimum 3-cm margin, is necessary to reducelocal recurrence in surrounding soft tissue.16

BONE TUMORSBenign Bone Tumors

The most common benign bony tumors of thechest wall include fibrous dysplasia (30%e50%),osteochondroma (30%e50%), chondroma(10%e25%), aneurysmal bone cyst (10%e25%),and eosinophilic granuloma,1 with many otherrarer tumors reported in the literature (seeTable 1).

Fibrous dysplasiaFibrous dysplasia is a developmental skeletaldisorder where normal bone marrow and cancel-lous bone is replaced by fibrous stroma andimmature bone. Patients with fibrous dysplasiatypically present with a painless mass in theposterior chest. Seventy to 80% of cases aremonostotic, with only one bone involved.6 Polyos-totic fibrous dysplasia, where more than one boneis involved, is much less common in chest walland rib lesions, although it can occur in thecontext of McCune-Albright syndrome, which is

Fig. 2. (A) Sarcoma of the middle third of the sternum, wsurgical resection, including soft tissue and skin; and (C) s

associated with cafe au lait spots, and endocrinedisorders, including Cushing syndrome, hyperthy-roidism, and acromegaly as well as classicallyshort stature and precocious puberty.5 Fibrousdysplasia occurs most commonly in the secondand third decades, with equal frequency in bothgenders. Pain develops if there is an associatedpathologic fracture or as growth causes perios-teal stretching. Its radiographic appearance isvariable (Fig. 4). On chest radiograph it is seenas a rib deformity with a central fibrous areawith fusiform expansion, a thin cortex, and oftena lytic component. As it matures, this lesion oftenhas a ground glass appearance due to variabledegrees of ossification within the lesion causingan increase in its density. On CT, amorphous orirregular calcifications may be seen.6 Histologi-cally, the lesion consists of irregularly shapedspicules of bone, that have been termed Chinesecharacters, due to their shape, with fibrousstroma consisting of regular spindle cells.19

Resection is only indicated for pain or if the diag-nosis is in question.

OsteochondromaOsteochondromas typically present in the seconddecade of life. They account for 50% of all benignbone tumors, with the rib, particularly at the cost-ochondral junction, the most common location.

ith complete resection of the sternum; (B) extent ofize of defect after resection.

Fig. 3. Creation of methyl methacrylate mesh sandwich. (A) Methyl methacrylate paste is first applied betweentwo layers of polypropylene mesh; (B) the methyl methacrylate mesh sandwich prosthesis is dried after conform-ing it to the shape of the defect; and (C) the mesh is sutured in with polypropylene sutures to cover the bonydefect of a sternal body resection. No muscle or skin flap was required.

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They account for only 2.7% to 8.5% of primary ribtumors.9 Most are round and measure less than9 cm. Imaging is usually adequate for diagnosis,demonstrating punctate or flocculent calcifica-tions with a mineralized hyaline cartilage capbest seen on CT. The cortex and medullary spaceblend into the underlying bone, which is howa definitive diagnosis is made on CT or MRI.6

These tumors can be observed with serial imaging.Cartilage caps thicker than 2 cm in adults and3 cm in children, however, are suspicious formalignant degeneration to chondrosarcoma orosteosarcoma and should be treated aggressivelywith wide local excision.

ChondromaAlso referred to as enchondromas, chondromasare benign cartilaginous tumors originating fromthe medullary cavity. They represent 2.8% to12.2% of all primary rib tumors9 and are typically

Fig. 4. Fibrous dysplasia of posterior eighth rib seen asa solitary, lytic expansile lesion on CT chest (arrow).There is no evidence of any overlying periosteal reac-tion, cortical disruption or soft tissue reaction aroundthe lesion.

found in the anterior portion of the rib. Plain filmradiographs demonstrate a slow-growing, well-demarcated, osteolytic lesion with mild expansionand well-defined sclerotic margins. Punctatecalcifications of the matrix and scalloping of thecortex are often seen, especially on CT andMRI.9 Microscopically, they have nodules ofhyaline cartilage with chondrocytes containingsmall, condensed nuclei. Chondromas can bedifficult to differentiate from low-grade chondro-sarcomas, even microscopically, and should,therefore, all be treated with wide local excision.

Langerhans cell histiocytosis/eosinophilicgranulomaCharacterized by idiopathic proliferation of histio-cytes, eosinophilic granuloma is one of thesyndromes seen with Langerhans cell histiocytosisthat produce single or multiple expanding erosivebony lesions. Langerhans cell histiocytosis rarelyarises from the chest wall but has been reportedin the ribs and sternum. A multifocal multisystemdisease, Langerhans cell histiocytosis in the bonesis characterized by focal lytic lesions with orwithout bone expansion and destruction. Diag-nosis is made with core needle or open biopsyby identifying Birbeck granules on electronmicroscopy. Rib lesions account for approxi-mately 10% of solitary eosinophilic granuloma,20

and are more commonly found in adults. Patientswith Langerhans cell histiocytosis typically presentwith systemic symptoms of fever and leukocytosisin association with localized pain. The lesions aregenerally osteolytic on imaging, with no matrixmineralization, which makes them radiolucent.Treatment includes intralesional and systemicsteroids, systemic chemotherapy,7 and low-doseradiotherapy for residual disease or high-gradetumors. Surgical resection is not indicated.

Aneurysmal bone cystAneurysmal bone cysts are rare, benign, locallyaggressive expansile cystic osteolytic lesions,

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accounting for approximately 5% of all primary riblesions.21 Their underlying cause is uncertain,although possibly originating as arteriovenousmalformations. These tumors may also be associ-ated with cystic changes in angiomas, chondro-blastomas, fibrous dysplasia, giant cell tumors,and osteoblastomas and can coexist with theselesions. The majority (75%) present before 20years of age. Aneurysmal bone cysts mostcommonly involve the posterior elements of thespine in the chest wall as well as the posterior orlateral aspects of any of the ribs.9 Radiographsdemonstrate a well-defined expansile lytic lesion.In early stages, they are confined to the cortexbut can progress to erode through the medullaryportion of the bone, with soft tissue extension,making them difficult to differentiate fromsarcomas. MRI may show fluid-fluid levels withinmultiseptated hemorrhagic cysts in the tumor,but these fluid levels can also be seen with simplebone cysts, giant cell tumors, and chondroblasto-mas.6 Microscopically, these tumors have blood-filled spaces without endothelial cell linings.Open biopsy is often needed to obtain diagnosisbecause needle biopsies usually only get a returnof blood. Complete excision is recommended forsymptomatic lesions.

Osteoid osteomaOsteoid osteomas are benign osteoblastic tumors.They typically present in the first two decades oflife. Most occur in the posterior elements of thespine. Only 0.23% to 2% occur in ribs, and osteoidosteoma accounts for only 1% to 1.4% of primaryrib tumors. They occur in the posterior portion ofthe rib and may lead to scoliosis. The mostdefining symptom of osteoid osteoma is nightpain that responds to both nonsteroidal anti-inflammatories and salicylates. Imaging revealsa small (<1 cm) radiolucent lesion, termed a nidus,best seen on CT, with a thick sclerotic margin ofreactive bone.1 These tumors have increaseduptake on bone scintigraphy and show soft tissueedema on MRI. Pathologically, the nidus containsosteoids at its center, with maturation into bonetrabeculae in a fibrovascular stroma. Treatmentis generally with radiofrequency ablation, andresection is rarely required.

OsteoblastomaOsteoblastomas, rare benign osteoblastic tumors,thought to be on continuum of osteoid osteomas,typically affect the posterior and posterolateralshaft of the rib. Imaging reveals a well-defined os-teolytic lesion (>2 cm) with slight expansion butwith a sharp sclerotic rim. CT allows accurate delin-eation of osseous involvement and type of

calcification. These tumors demonstrate increaseduptake on bone scans. Histologically, osteoblasto-mas are characterized by interconnected trabec-ulae of bone in a fibrovascular stroma.5

Giant cell tumorGiant cell tumors, benign lesions, are common.They present between the ages of 20 and 40 years,more frequently in men than women. Consisting ofvascular sinuses lined and filled with giant cellsand spindle cells, radiographs demonstrateeccentric, osteolytic expansile masses withcortical thinning. Giant cell tumors often presentwith a soft tissue mass. CT helps define the extentof tumor involvement of surrounding structures.MRI is better with soft tissue delineation, in whichgiant cell tumors are dark on both T1- and T2-weighted images. Although generally consideredbenign, these tumors are locally aggressive andhave a 30% to 50% risk of local recurrence9 andmay even rarely metastasize.5

Malignant Bone Tumors

In descending order of incidence, chondrosarcoma,Ewing sarcoma, osteosarcoma, and solitaryplasmacytoma are the most common malignantbony tumors of the chest wall. Although multiplemyeloma, presenting as a solitary plamacytoma,often appears in the literature as the mostcommon malignancy of the bony chest wall, it ismore accurately defined as a local presentationof a systemic disease and not a primary chestwall lesion.1 The rib is the most common boneinvolved in malignant tumors of the chest wall, fol-lowed by the scapula, sternum, and clavicle.

ChondrosarcomaChondrosarcoma is the most common primarybone tumor of the chest wall in adults.22 Originatingfrom cartilage, chondrosarcomas may develop denovo from normal bone or can degenerate frombenign cartilage tumors, such as chondromas,exostoses, or osteochondromas. They are, there-fore, typically found anteriorly in the chest wall orin the sternum. On imaging, they demonstratebony destruction, irregular contours, and varyingdegrees of calcification.23 Early-stage lesionsdemonstrate a thickened cortex whereas higher-grade lesions usually have complete corticaldestruction, along with a soft tissue mass (Fig. 5).Alternatively, the growth of a benign cartilage tumoror expansion of their cartilage cap may suggestmalignant degeneration. CT and MRI allow deter-mination of tumor extension as well as areas ofscattered calcification in the chondroid matrix.24

Pathologically, the tumordemonstrates a chondroidmatrix with increased cellularity, binucleate cells,

Fig. 5. Chondrosarcoma of the sternum with corticaldestruction, soft tissue extension posteriorly into themediastinum and anteriorly into subcutaneoustissues, focal calcification within the tumor, andcompression of both the right ventricle and atrium,as seen on CT chest.

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with the degree of cellularity, mitoses, and cytologicatypia determining tumor grade. These tumors areunresponsive to chemotherapy or radiation and,therefore, complete wide local surgical resectionis the only chance of cure.

Ewing sarcomaMalignant, small, round celletype tumors area highly malignant group of tumors that sharea common (t11;22) (q24;q12) translocation.25

They include Ewing sarcoma and PNETs, alsoknown as Askin tumors. Typically occurring in chil-dren to young adults, with a male predominance of1.6:1,24 6.5% of malignant small round celletypetumors arise in the chest wall, with a single ribthe most common site of occurrence,3 followedby the clavicle, then scapula. Approximately 15%of Ewing sarcomas24 and 50% of PNETs arise inthe chest wall.26 Malignant small round celletypetumors often present with a painful chest wallmass associated with systemic symptoms, suchas fever, malaise, and weight loss. Dyspnea,caused by associated pleural or pericardial effu-sions, is also common. Imaging demonstratesa large, noncalcified, soft tissue mass associatedwith bone destruction. The periosteal reactionclassically takes on an onion peel or sunburstappearance. Diagnosis is made with incisionalbiopsy, with demonstration of small round bluecells with scanty clear cytoplasm and positivestaining on periodic acideSchiff due to the pres-ence of glycogen. Rosettes, dark oval nuclei withneurofibrillary cores, are found in PNETs and notin Ewing, and are, therefore, used to distinguish

between the two tumors.27 Treatment is neoadju-vant chemotherapy, followed by surgical resectionif the tumor is well demarcated, and can becompletely resected with wide resection. Chemo-therapy often shrinks the tumor, making subse-quent chest wall resection less morbid as well asincreasing overall 5-year survival to approximately60%.28 Resection, however, should incorporatethe pretreatment extent of disease. Radiotherapyis less frequently used today as postoperativeadjuvant treatment. The addition of myeloablativetherapy and stem cell rescue may improveoutcome in patients with primary metastatic Ewingsarcoma.29 Bilateral whole-lung radiation mayimprove event-free survival in patients with lung,bone, or bone marrow metastases.3

OsteosarcomaOsteosarcoma is the most common overall bonetumor, but in chest wall bony tumors it is secondafter chondrosarcomas. Osteosarcomas generallypresent in puberty. In a recent review of the litera-ture by Eyre and colleagues,30 consisting of smallnumber of case-control and cohort studies,possible risk factors for the development of osteo-sarcoma emerged. These included environmentaltriggers, such as high fluoride exposure and resi-dency on a farm or a parent working as a farmer,as well as genetic predisposition: family history ofmalignancy, younger age at puberty, associationwith other musculoskeletal anomalies, and multiplebirth defects. Retinoblastoma (RB1 mutation onchromosome 13q14) carries a 500� to 1000� riskof developing osteosarcoma than the general pop-ulation and Li-Fraumeni syndrome (p53 mutation)a 15-fold increased risk. Osteosarcomas typicallyarise from a rib, scapula, or clavicle. On CT andMRI they are osteoblastic lesions that demonstratebone destruction with a large heterogeneous massdue to hemorrhage or necrosis. They demonstratea pattern of mineralization concentrated at thecenter of the lesion (Fig. 6).23 On biopsy thesetumor cells are spindle-shaped, epithelioid, or smalland round, with osteoid matrix calcification. Unlikechondrosarcomas, these tumors are responsive tochemotherapy and are treated first with neoadju-vant chemotherapy followed by surgery.24,31 Inthe event of metastases, subsequent pulmonarymetastectomy can increase long-term disease-free survival and overall survival. Even with adjuvanttreatment, however, the overall 5-year survival forosteosarcoma has been reported as low as 15%.4

Solitary plasmacytomaSolitary plasmacytomas are uncommon solitarylesions, which, unlike disseminated myeloma, aretreated with surgical resection or with local

Fig. 6. (A) Axial and (B) coronal CT chest images of an osteosarcoma of the right chest wall at the level of sixth ribwith rib involvement and extension into subcutaneous tissue.

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irradiation. Two-thirds of patients progress todevelop generalized myeloma within 3 years ofdiagnosis, with poor prognosis, but the remainderof the patients achieve permanent cure.

BENIGN SOFT TISSUE TUMORS

The differential of soft tissue abnormalities is vastand, in addition to primary tumors, should encom-pass local presentations of systemic diseases aswell as infectious causes, such as tuberculosisand actinomycosis. In terms of primary benignsoft tissue tumors (see Table 1), the most commondiagnoses include lipomas, fibromas, hemangi-omas, and giant cell tumors.32 Less common diag-noses include lipoblastomas and mesenchymalhamartomas.

Lipomas

Lipomas are well-circumscribed adipose massesthat can occur in patients of any age but are typi-cally found in obese and older patients betweenthe ages of 50 and 70 years of age. On the chestwall, they are often larger and deeper than lipomason other sites of the body. CT and MRI demon-strate homogenous masses consistent withmature fatty tissue. They can be difficult to differ-entiate from low-grade liposarcomas on imaging.

Lipoblastoma

Lipoblastomas are uncommon benign tumors offetal embryonic fat that present as a painless chestwall mass in infants. These tumors are bright onT1-weighted MRI, and, although benign, theyoften have intercostal extensions. Wide localresection is, therefore, required to ensure negativemargins.

Fibromas and Fibromatosis

Fibromas are localized benign tumors of connec-tive tissue, also termed desmoid tumors.Although considered benign, these tumors canbe locally aggressive. They are seen in associa-tion with Gardner syndrome (mutation of theadenomatous polyposis coli gene) and in scarsof previous thoracotomies.7 Surgical resectionwith negative margins is required to prevent localrecurrence, because they have local recurrencerates up to 70%.4,33 Aggressive fibromatosisdescribes a more extensive infiltrative diseaseof fibrous scar tissue. It is treated with eitherwide excision or, if unresectable, chemotherapyand radiation.20

Hemangiomas

Hemangiomas are usually large, benign prolifera-tions of blood vessels that form within subcuta-neous tissue, muscle, ribs, or vertebrae. Theyusually occur before the age of 30 and areuncommon on the chest wall. CT demonstratesheterogeneous soft tissue masses with fatty,fibrous, and vascular elements. Ultrasound canbe used to determine flow within the lesion andMRI to show vascular and adipose componentsof the lesion. In infants, cavernous hemangiomatacan cause fetal hydrops and death due to cardiacfailure from arteriovenous malformation andshunting. Thrombocytopenia is also seen inKasabach-Merritt syndrome due to plateletsequestration.26

Benign Peripheral Nerve Sheath Tumors

Benign peripheral nerve sheath tumors consist ofneurofibromas and schwannomas, also referredto as neurilemmomas and neurinomas. Schwan-nomas are encapsulated tumors that originate

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from intercostal nerves or spinal nerve roots. Theyare usually only seen on CT or MRI as a homoge-nous mass, although bone scalloping may be seenon plain radiographs. They are extremely painfulon biopsy, giving a diagnostic clue as to theirorigin. Neurofibromas originate from peripheralnerves and in up to 60% can be associated withneurofibromatosis type I, multiple plexiform neuro-fibromas, or multiple endocrine neoplasia.26 Theyare slow-growing masses, often occurringbetween the ages of 20 and 30 years.6 They maydemonstrate cystic degeneration, with a centralzone that is more cellular and a peripheral morestromal zone, creating a target appearance onboth T2-weighted images and gadolinium-enhanced MRI. These tumors can grow into thespinal canal in a dumbbell fashion.

Mesenchymal Hamartomas

Mesenchymal hamartomas, also referred to asmesenchymomas, present in infancy, often withchest deformity and respiratory distress. Theselarge tumors can be solitary or multifocal andmust be differentiated from aneurysmal bonecysts and chondromas. Partially calcified onimaging, they often demonstrate chondroid tissuemixed with immature mesenchyme, osteoclasts,and endothelium-lined blood spaces onpathology. Wide local excision is recommendedif there is respiratory or cardiac compromise.7

MALIGNANT SOFT TISSUE TUMORS

More common than malignant tumors of the bonythorax, most malignant soft tissue tumors of thechest wall are sarcomas, including malignantfibrous histiocytomas, liposarcomas, and fibrosar-comas. They are often asymptomatic and morecommonly found on the anterior chest wall. Mostsarcomas have a poor prognosis, with survivalinfluenced by histology, tumor grade, diameter,and location. Reported overall 5-year survival isstill only 50% to 66%, although low-grade well-differentiated tumors treated with wide local exci-sion can achieve 5-year survival rates up to 90%.34

The mnemonic, SCARE, is used to recall thosesarcomas that most commonly metastasize tolymph nodes: synovial sarcoma, clear cell, angio-sarcoma, rhabdomyosarcoma, and epithelioidsarcoma.35

Malignant Fibrous Histiocytoma

Malignant fibrous histiocytoma usually occurs inolder patients but has a bimodal distribution, witha first peak from 20 to 30 years of age, anda second, larger peak from ages 50 to 60.

Although they are the most common radiation-induced tumor24 and the most common soft-tissue tumor in adults, they rarely arise from thechest wall. On imaging, they are heterogeneouswith ill-defined contours. MFH is generally diag-nosed with biopsy and treated with neoadjuvantchemotherapy, followed by surgical resectionand further adjuvant chemotherapy.24

Synovial Sarcomas

Synovial sarcomas are extremely rare in the chestwall. Presenting in adolescence to early adulthood,they are calcified in 20% to 30% of patients. Theseheterogeneous masses demonstrate fluid-fluidlevels on MRI due to hemorrhage and necrosiswithin their cystic components. Treatment includesexcision followed by adjuvant radiation, althoughradiation can also be used preoperatively. Thesetumors can also be treated with chemotherapy,because they are 50% chemosensitive.36 Five-year survival is approximately 50%.24

Rhabdomyosarcoma

Uncommon in adults, rhabdomyosarcoma is thesecond most common malignant chest wall tumorin children. These tumors are treated with neoad-juvant chemotherapy and radiotherapy, followedby surgical resection, then ongoing chemotherapyand radiation.28 Negative prognostic featuresinclude alveolar subtype (compared with embry-onal subtype), invasive tumors greater than10 cm, and R1 resections.28 Preoperative work-up should include MRI of the primary tumor andfull staging with CT thorax, abdominal ultrasound,and bone scans to rule out metastatic disease.These are aggressive tumors and only app-roximately 10% of rhabdomyosarcomas areresectable.26

Fibrosarcoma

Fibrosarcomas occur in adults as heterogeneousmasses on CT and MRI, due to necrosis andhemorrhage. Treatment includes neoadjuvantchemotherapy followed by resection. Postopera-tive radiation is used for positive margins. Theselesions tend to both recur locally and metastasize.Neurofibrosarcomas typically present with anenlarging painful mass. Also referred to as malig-nant schwannomas or malignant peripheral nervesheath tumors, neurofibrosarcomas often origi-nate from neurofibromas of spinal nerve roots orintercostal nerves or in the brachial plexus. Theyare most common in adults and can be associatedwith previous irradiation. Close to one-third (29%)of patients with neurofibromatosis developneurofibrosarcomas.24

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Other Primary Malignant Tumors

Many other sarcomas, including leiomyosarcomasand neuroblastomas, can arise infrequently in thechest wall. Leiomyosarcomas, arising from bloodvessels, including pulmonary arteries, can alsopresent in cutaneous and subcutaneous tissues.Arising in adulthood, they have been associatedwith immunosuppression, including organ trans-plantation, AIDS, and Epstein-Barr virus. They arepainful and unresponsive to chemotherapy. Neuro-blastomas uncommonly involve the chest wallprimarily. They arise in sympathetic nervous tissue,usually before the age of 5. They can invade theneural foramina causing a dumbbell appearance.Localized excision is the treatment of choice,possibly followed by boost of external beamradiation.7

Undifferentiated or spindle cell sarcomas arethose sarcomas that cannot be more accuratelyclassified. These sarcomas are often large, withheterogeneous attenuation and signal intensityon CT and MRI, respectively. Treatment typicallyinvolves resection and radiation, with the additionof chemotherapy preoperatively in some cases toshrink tumors initially judged unresectable.

Systemic Diseases

Although not considered primary lesions of thechest wall, systemic diseases can present aschest wall masses that can be confused with chestwall tumors and, therefore, are briefly discussed.Both leukemia and lymphoma can present asa chest wall mass. Multiple bone lesions are oftenseen with leukemia. Lymphoma can present asprimary bone lymphoma, multifocal lymphoma,or lymphoma with both nodal and osseousdisease.26 Diagnosis is made with a biopsy. Clas-sically, Reed-Sternberg cells are seen in Hodgkinlymphoma, and flow cytometry or immunohisto-chemistry is used to determine cell lineage innon-Hodgkin lymphoma. Treatment is systemicchemotherapy. Surgical resection is not generallyindicated.7

Myeloma, a malignant tumor of plasma cells,accounts for 50% of malignant bony tumors ofthe chest wall but is not considered a primarytumor. It is associated with multiple bone siteswith widespread osteolytic bone destruction,hypercalcemia, renal dysfunction, and refractoryanemia. A solitary lesion associated with multiplemyeloma is termed a solitary plasmacytoma (dis-cussed previously). Diagnosis is made with mono-clonal elevation of IgG, IgA, or Bence Jones lightchains on serum immune electrophoresis. Chemo-therapy, with autogenous bone marrow transplan-tation, is commonly used as standard treatment,

with radiation for localized areas of symptomaticinvolvement. In the chest wall, surgical resectionis not indicated.Infections can also present as a chest wall mass

or abscess, either as a primary site or as localextension from a deep chest infection (ie,empyema or mediastinitis). A diagnosis of tuber-culosis is aided by a positive contact or travelhistory, in combination with mediastinal lymph-adenopathy. Surgical drainage and resection,with debridement of any necrotic bone or tissue,is the treatment of choice in combination withsystemic antituberculous treatment. Actinomy-cosis can also mimic a chest wall tumor with ribdestruction. It is diagnosed by the developmentof sinus tracts and pathognomonic sulfur granuleson fine needle aspiration. Treatment is withsystemic penicillin G, with possible surgicaldrainage or resection if required.7

SURGICAL TREATMENT OF CHEST WALLTUMORS

The indication for surgery is based on evaluation ofthe tumor histology, location, degree of local inva-sion, and presence of metastases. Localization ofsmall tumors, or for those with significant responseto neoadjuvant treatment, may be difficult. Video-assisted thoracoscopic surgery may facilitatetumor localization if the tumor is visible from thepleural surface. Entering the pleura one or tworibs above or below the lesion may allow palpationof the defect. If the lesion is too small to beobserved directly or by palpation, preoperativecoil wire placement by interventional radiology orthe use of image-guided methylene blue injectioninto surrounding tissues allows intraoperativelocalization and resection.Most chest wall tumors are treated primarily with

surgical resection. Exceptions include Ewingsarcoma and solitary plasmacytomas. Ewingsarcoma is first treated with sequential chemo-therapy and radiation, followed by possiblesurgical resection. Solitary plasmacytoma istreated solely with radiation. Surgical resection ofall tumors must ensure negative margins toprevent local recurrence, although the exactmargin size is somewhat debated depending onthe specific tumor type. Most benign tumors areexcised with simply negative margins, whereasmany agree that locally aggressive benign lesionsand malignant tumors require a minimum 4 cmmargin for wide excision. With rib lesions, the exci-sion should generally incorporate resection of allor most of the rib involved, a portion of any adja-cent ribs, and en bloc resection of any attachedstructures, including portions of pleura, lung,

Primary Chest Wall Tumors 505

pericardium, thymus, or diaphragm. Malignanttumors of the manubrium, sternum, clavicle, andscapula generally require excision of the entirebone and surrounding soft tissue to ensure nega-tive margins.

Reconstruction

Chest wall surgery must be carefully planned toensure accurate localization of the lesion, completeresection, and adequate tissue coverage, withminimum morbidity. Chest wall closure for smallerlesions can usually be done primarily, but for largertumors in which a considerable defect is antici-pated, both skeletal reconstruction and soft tissuecoverage are often necessary. Involvement ofa multidisciplinary team, including plastic surgeons,is often invaluable. Although there is no trueconsensus, in general, chestwall defects are recon-structed when they measure more than 10 cm pos-teriorly, greater than 5 cm in any other location, orare located where the scapular tip falls (to preventa trapped scapula). Subscapular and apical chestwall resections generally do not require reconstruc-tion. In a report of 500 chest wall reconstructions,275 of which were performed for chest wall tumors,the majority underwent pedicled or myocutaneousflaps with pectoralis major or latissimus dorsi,although serratus anterior, rectus abdominis, andexternal oblique muscles were also used. Syntheticmaterials used included polypropylene (Marlex) orpolytetrafluorethylene mesh.37 Others report use ofomental, thoracoepigastric fasciocutaneous, andchimeric flaps as well as reconstruction with methylmethacrylate sandwiched between two layers ofpolypropylene mesh to provide chest wall stability,protect underlying vital structures, and restorebody contour (see Fig. 3).38 Choice of reconstruc-tiondependssomewhaton theexpertiseandprefer-ences of the involved thoracic and reconstructivesurgeons. In general, latissimus dorsi flaps areused for largeposteriordefects andpectoralismajorflaps for anterior defects.

Postoperative respiratory morbidity is related toimpaired respiratory function and chestmechanics after chest wall resection. Complica-tions have been reported in 46% to 69% ofpatients,39,40 with respiratory complications in upto 24%,41 often due to a flail segment created re-sulting in paradoxic movement, atelectasis, pool-ing of secretions, and subsequent respiratoryfailure, pneumonia, or acute respiratory distresssyndrome. For large defects, it is thus desirableto use the Marlex methyl methacrylate compositereconstruction technique to provide a chest wallreconstruction with stability to prevent flail andrespiratory compromise. Other common

complications include wound infections andcardiac arrhythmias. In a recent series of 262 chestwall resections, in which 251 were for tumors,significant predictors of postoperative complica-tions were patient age, concomitant anatomiclung parenchymal resection, and increased sizeof chest wall defect resected.41 Risk factors forwound infection include tumor ulceration and theuse of omentum in soft tissue reconstruction.42

Adjuvant Treatment

Multimodality therapy is critical in the treatment ofspecific chest wall tumors. The use of multiagentchemotherapy both in the neoadjuvant and adju-vant settings for osteosarcoma and malignantsmall round celletype tumors (Ewing sarcomaand PNETs) has been critical in significantlyimproving the overall and disease-free survival ofpatients with these tumors. The use of adjuvantradiotherapy is also used with certain tumors,including malignant soft tissue tumors and osteo-sarcomas, to prevent local recurrence and to treatrecurrent tumors.

SUMMARY

The differential diagnosis of patients presentingwith a lesion on the chest wall must take intoaccount local anatomy as well as patient age,gender, previous history of malignancy, andexposure to radiation. In addition to benign ormalignant primary chest wall tumors, diagnosticpossibilities include local presentations ofsystemic disease, infection, metastasis, orextension of underlying malignancies. Withparticular attention to imaging characteristics ofthe lesion, a diagnosis can often be made.Use of plain radiographs, CT, and MRI furtherfacilitate decision making in how to best obtaintissue diagnosis without compromising potentialfuture surgical resection and allows for operativeplanning. Treatment decisions are guided by thelocal aggressiveness of the tumor, its malignantpotential, and its responsiveness to chemo-therapy and radiotherapy. These tumors shouldbe assessed and treated in a multidisciplinarysetting, with a priori involvement of thoracicsurgery, medical, and radiation oncology aswell as plastic surgery when reconstruction isrequired, so that an appropriately ordered multi-modality treatment plan can be set in place tooptimize patient outcome.

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