J Oral Maxillofac Surg 54:1446-1450, 1996

Retromolar Swelling in a 6 I -Year-Old Woman

EVAN D. CHAFITZ, DMD,* HARRY G. SACKS, DDS,t JOSEPH MORALES, DDS,$ AND WILLIAM J. NELSON, DDS§

Case Presentation

A 61-year-old woman was referred by her general dentist for evaluation of a “cyst” in the right mandibular retromolar area. She had consulted the general dentist because of swell- ing and discomfort. He had noted a soft swelling in the retromolar region and a supraerupted maxillary third molar in traumatic occlusion. A p&apical radiograph failed to show the presence of a mandibular third molar. The maxil- lary third molar was uneventfully removed under local anes- thesia. When the soft tissue lesion failed to resolve, the patient was referred for further evaluation.

The medical history was negative for any systemic dis- ease. The patient also had a negative drinking and smoking history. Physical examination showed a well-developed, well-nourished 61-year-old woman in no acute distress. There was no extraoral swelling or lymphadenopathy. The cranial nerve examination was unremarkable; no paresthesia or motor nerve deficit were present.

Intraoral examination showed a complete succadaneous dentition with the exception of teeth 1, 16, and 32. The dentition was grossly intact, without obvious caries. The oral mucosa and gingiva showed no generalized changes. A 1 cm X 1 cm swelling was present in the right retromolar trigone. The overlying mucosa was thin, translucent, and the lesion appeared to be fluid filled (Fig 1). There was no devia- tion of the uvula. Aspiration produced a thick mucoid mate- rial. Positive findings on the panoramic radiograph included a recent extraction site (upper right third molar) and periapi- cal pathology involving the lower right first molar. No in- traosseous pathologic condition was seen in the body or ramus of the posterior mandible (Fig 2). A soft tissue swell- ing could be seen over the ascending ramus.

Under local anesthesia (2% Xylocaine [Astra, Westboro,

* Former Chief Resident in Oral and Maxillofacial Surgery at Metropolitan Hospital Center/New York Medical College. Now in private practice in Forest Hills, NY.

t Assistant Director Advanced Training Program in Oral and Maxillofacial Surgery at Metropolitan Hospital Center, Assistant Clinical Professor, New York Medical College, and in private prac- tice in New Hyde Park, NY.

$ Chief of Dental Service, Metropolitan Hospital Center, and AY- sociate Professor and Chairman, Department of Dentistry, New York Medical College.

5 In Private Practice, Green Bay, WI. Address correspondence and reprint requests to Dr Sacks: 2035

Lakeville Rd, Suite 204, New Hyde Park, NY 11040.

0 1996 American Association of Oral and Maxillofacial Surgeons

0278-2391/96/5412-0010$3.00/0

MA] with l:lOO,OOO epinephrine), an incisional biopsy was performed. Appropriate postoperative antibiotics and analge- sics were prescribed. The tissue was submitted to an oral and maxillofacial pathologist for microscopic examination.

Differential Diagnosis

William J. Nelson, DDS

The uncertain history of this retromolar mass in a 61-year-old, healthy-appearing woman requires the in- clusion of many entities in the differential diagnosis. An inflammatory process resulting from trauma caused by a supraerupted maxillary molar was an initial con- sideration. Failure of this swelling to resolve after re- moval of the maxillary tooth, however, would seem to preclude direct trauma as the causative factor. The probability that the lesion was increasing in size is more plausible than the tooth supraerupting to the point of contact with the retromolar tissue.

The panoramic radiograph does not show any corti- cal or intraosseous retromolar pathology. Soft tissue swelling is radiographically apparent. The mandibular first molar tooth has a large restoration and periapical pathology. It is presumed from the history that this tooth was asymptomatic. It is likely that this was an incidental finding. A periodontal cause is not evident by history, examination, or radiography. The lack of bony involvement, and no evidence of nerve distur- bance, would render a primary intraosseous process very unlikely.

Odontogenic cysts need to be considered based on the clinical appearance and location of this lesion. A primordial cyst, dentigerous cyst, or odontogenic kera- tocyst would be expected to show bony involvement. The gingival cyst of adults is derived from the dental lamina (rests of Serre) and usually occurs in patients older than 40 years of age. This is strictly an extraosse- ous entity and is located in the free or attached gingiva.

Odontogcnic tumors, such as peripheral ameoloblas- toma, calcifying epithelial odontogenic tumor, adeno- matoid odontogenic tumor, and calcifying odontogenic cyst may occur over a wide range of ages. The usual presentation is as a painless mass, and any of these may occur as extraosseous lesions.

1446

CHAFITZ ET AL 1447

FIGURE 1. Fluid-filled swelling in the left retromolar region.

Benign neoplasms of soft tissue also warrant consid- eration. Peripheral giant cell granuloma occurs on the gingiva or alveolar mucosa of both tooth-bearing and edentulous areas. This lesion rarely exceeds 2 cm in size and usually is red or reddish-blue in color. Favored sites are the incisor or canine regions, but it may be found in any alveolar area. Fibroma must be considered because this is the most common benign oral soft tissue neoplasm. The fibroma is often recognized as a repara- tive or hyperplastic lesion that would be consistent with the traumatic circumstances surrounding the ret- romolar mass in this patient. Based on clinical appear- ance alone, one would not be disposed to include tu- mors of vascular, lipomatous, or neurogenic origin as serious causative considerations.

Squamous cell carcinoma deserves some mention, primarily because of the history of trauma from the upper molar tooth. However, the patient denies alcohol and tobacco use, she appears in good health, and is in no acute distress. The clinical appearance of this mass is not typical of squamous cell carcinoma, which is usually ulcerated. Pain on manipulation, bone involve- ment, and regional lymphadenopathy are common findings.

Malignant mesenchymal tumors are rare in the oral and maxillofacial region. Fibrosarcoma usually devel- ops in patients 20 to 40 years of age. The cheek and lips are favored sites, although periosteum of the man- dible has been reported as an area of occurrence. The age of this patient would make fibrosarcoma an even rarer event. Malignant fibrous histiocytoma, however, is the most common oral soft tissue sarcoma seen in later adult life. The clinical appearance and presenta- tion of both of these entities may be quite variable. Osteogenic sarcoma and chondrosarcoma may present as painless soft tissue swellings with intact mucosa. Radiographically, they may appear to be adjacent to bone. Osteogenic sarcoma is found in younger individ- uals, and typically pain, paresthesia, and loose teeth

are present. Chondrosarcoma has a male preponder- ance and a peak incidence in the third to fifth decades. Although juxtacortical presentation is possible for both osteogenic sarcoma and chondrosarcoma, they merit only minor consideration in this case.

Extraosseous plasma cell tumor must be included in the evaluation of this mass. There is a predilection for the upper respiratory tract and oral tissues in individu- als older than 40 years of age. Males predominate in a 3:l ratio. This tumor has great variability in color and consistency. Regional node involvement has been reported in approximately 25% of extraosseous plasma cell tumors. Extranodal non-Hodgkin’s lymphoma is a possible prospect because of the patient’s age and location of the mass.

Minor salivary gland pathology requires serious consideration in the diagnosis of this mass. Mucocele and mucous retention cyst would be consistent with a history of trauma: the clinical appearance, and the aspiration of a mucoidlike fluid. Benign mixed tumor is the most common minor salivary gland neoplasm, and the palate is the most common site of presentation. Slow growth, intact mucosa, and the lack of pain are consistent with the history and clinical appearance of this mass. Other benign salivary gland tumors such as oncocytoma, monomorphic adenoma, canalicular ade- noma, and myoepithelioma are uncommon entities in the retromolar region.

Mucoepidermoid carcinoma also merits primary consideration in the differential diagnosis of this ret- romolar mass based on the clinical appearance and location. Fluid is commonly found in this tumor as a result of cystlike areas of mucus retention. Absence of regional lymph node involvement is not uncharacteris- tic of this minor salivary gland neoplasm. Polymor- phous low-grade adenocarcinoma (PLGA) is most commonly found in the hard palate, upper lip, and

FIGURE 2. Panoramic radiograph shows a soft tissue swelling distal the second molar, with no osseous changes in the area.

1448 RETROMOLAR SWELLING IN A 61.YEAR-OLD WOMAN

cheek. There is a distinctive predilection for women, particularly during the sixth to eighth decades. Gender, age, clinical appearance, and lack of regional lymph node involvement are consistent with PLGA in this patient, but the location strongly favors mucoepider- moid carcinoma over PLGA. Adenoid cystic carci- noma has a peak incidence during the fifth to seventh decades. There are conflicting data as to whether there is a female preponderance. This slow-growing tumor rarely causes pain and, even though perineural invasion is a recognized feature, motor or sensory deficits are typically a late finding. Acinic cell carcinoma and ma- lignant mixed tumor are very infrequent in minor sali- vary glands. The malignant mixed tumor may have a mutinous component. Adenocarcinoma not otherwise specified (NOS) is a term used to describe minor sali- vary gland malignancies with a wide range of histo- pathologic features. The palate is a favored site, and cystic change is not generally present. Adenocarci- noma (NOS) has a peak incidence in the sixth through eighth decades. It is recognized for infiltrative growth, pain, and regional as well as distant metastasis.

In summary, the bluish hue and aspiration of mu- coidlike material place a minor salivary gland cyst or tumor at the top of the list in determining the nature of this lesion. It is appropriate to consider a retromolar mass with the character of this lesion as a mucoepider- moid carcinoma until proved otherwise. Mucocele and mucous retention cyst are consistent with the clinical presentation, but are rarely found in the retromolar area. The history of trauma does not allow the exclu- sion of mucous retention phenomena based on location alone. Benign and malignant mixed tumors, canalicular adenoma, and mutinous adenocarcinoma also have the potential for cystic development.

Subsequent Clinical Course

Microscopic examination of the biopsy specimen showed a wedge of tissue surfaced by stratified squa- mous epithelium. The underlying stroma consisted of fibrous connective tissue and minor salivary gland lob- ules. A polycystic lesion was noted subjacent to the epithelium. The cystic areas were lined by cuboidal ductal epithelium with areas of epidermoid and mucous differentiation. Mucin pooling was noted as well. The microscopic findings were consistent with a diagnosis of low-grade cystic mucoepidermoid carcinoma (Fig 3, 4).

The patient was advised of the diagnosis and re- ferred for evaluation and surgical treatment. Computed tomography (CT) was obtained to delineate the lesion. Wide surgical excision and partial ostectomy was ad- vised based on the evaluation of the extent of the lesion on the CT scan. Because of financial considerations,

the patient sought definitive treatment at a municipal facility and was lost to follow-up.

Discussion

Proper diagnosis and treatment of salivary gland neoplasms can be a difficult task, because lesions ex- hibit a wide variety of clinical behavior. Although his- tologic findings assist pathologists in categorizing these lesions, frequently biologic behavior varies within individual diagnostic categories. Mucoepider- moid carcinoma (MEC), the most common malignant lesion of salivary glands, is a classic example of this problem.

MEC has been shown to represent 19% of all sali- vary gland lesions and 41% of those that were malig- nant in a recent Armed Forces Institute of Pathology study.’ The parotid is the gland most often affected; however, MEC also occurs in the other major and mi- nor salivary glands. Rare cases of primary intraosseous MEC also have been reported.2 MEC typically is seen with equal frequency in men and women during the third to fifth decades of life. It is the most common salivary gland malignancy in children.334

In 1945, Stewart et al5 divided mucoepidermoid le- sions into favorable and unfavorable groups, implying a benign variant.’ Subsequently, others have chal- lenged this premise, and most now consider all muco- epidermoid tumors to be malignant.4 Several authors have attempted to correlate clinical findings with histo- logic criteria to help predict biologic behavior.‘%7,8 MECs are now routinely categorized as low, intermedi- ate, and high grade.’ Low-grade tumors usually appear as a slow-growing, painless mass similar to the pleo- morphic adenoma. They are usually less than 5 cm in diameter and lack complete encapsulation. They have a propensity for the retromolar trigone, tongue, palate, and buccal mucosa. High-grade tumors have a more rapid growth rate and frequently produce pain as an early symptom. They infiltrate regional structures and metastasize to local lymph nodes. Distant metastatic spread is also common.

Histologically, MEC is composed of three cell types in varying amounts: mucus secreting, epidermoid, and intermediate cells.” Sheeting of the epidermoid com- ponent, and mucus cells arranged in a glandular pattern with occasional microcyst formation, are the classic microscopic findings.” In low-grade tumors, the mu- cus component predominates, whereas the epidermoid cell is prominent in the high-grade lesions. In some high-grade lesions the absence of mucus-producing cells may be striking, requiring special stains to con- firm their presence.6 They are an important finding in differentiating a high-grade MEC from other epider- moid carcinomas.

Since Stewart’s original grading classification, many

CHAFITZ ET AL

FIGURE 3. Polycystic lesion composed of cuboidal ductal ep- ithelium and areas of mucous and epidermoid differentiation. Mucin pooling is also present (hematoxylin-eosin stain, origi- nal magnification X 10).

authors have tried to present a scheme that would cor- relate prognosis with clinical or histologic criteria. Auclair et al’ noted that the presence of pain, short clinical duration, and location in the tongue or floor of the mouth were associated with a poor prognosis. Histologically, an intracystic component of less than 20%, presence of more than four mitotic figures per 10 high-power fields, neural invasion, necrosis, and

cellular anaplasia were also associated with a poor prognosis. He proposed a grading scale that assigned point values to each of these criteria, with cumulative scoring placing lesions into low-, intermediate-, and high-grade groups. Clode et al8 also correlated the tu- mor characteristics with patient survival. They used criteria similar to Auclair et al but included the grading system suggested by Healy et a1,9 separating MECs

FIGURE 4. Photomicrograph showing epidermoid differentia- tion and mucous pooling (hema- toxylin-eosin stain, original magnification X40).

1450 RETROMOLAR SWELLING IN A 61-YEAR-OLD WOMAN

into groups based on the percentage of the mucous component present. The study reported 39 cases all treated with surgery and 19 also treated with adjuvant radiation therapy. The 5-year survival rate was 100% for grade I lesions, 70% for grade II lesions, and 0% for grade III lesions. The calculated 2-year survival rate was 42.7%. Spiro et al7 found a 92%, 83%, and 27% 5year survival rate for low-, intermediate-, and high-grade lesions, respectively.

Surgical therapy includes wide local excision of the lesion, with associated neck dissection when indicated, particularly with high-grade lesions that exhibit nodal involvement. Preoperative or postoperative adjunctive radiation therapy has been used for high-grade lesions with some success.12 Metastases are not uncommon in higher-grade lesions and should be considered in the workup of all patients with a diagnosis in MEC. Recur- rence is not uncommon up to 10 to 15 years after initial treatment; therefore long-term follow-up is mandatory. Because it may imply false information or mislead the clinician, many authors and pathologists no longer re- fer to an intermediate grade.13

Although it appears that histologic grade and clinical course have a direct correlation, there are often tumors that exhibit unanticipated activity. Case reports exist of low-grade tumors metastasizing’ and of histologically high-grade lesions exhibiting a benign clinical course with good patient survival. MEC is a complex entity and can present difficult diagnostic and treatment di- lemmas. The best patient survival rates can be assured when the histologic specimens are evaluated by a pa-

thologist with extensive training and experience in sali- vary gland pathology and correlated with the surgeon’s physical examination findings.

References

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2. Waldron CA, Koh ML: Central mucoepidermoid carcinoma of the jaws. J Oral Maxillofac Surg 48:871, 1990

3. Krolls S, Trodahl J, Boyers R: Salivary gland lesions in children: A survey of 430 cases. Cancer 30:459, 1972

4. Castro E, Huvos A, Strong E: Tumors of the major salivary glands in children. Cancer 29:312, 1972

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12. Sadeghi A, Tran LM, Mark R, et al: Minor salivary gland tumors of the head and neck: Treatment strategies and prognosis. Am J Clin Oncol 16:3, 1993

13. Evans HI: Mucoepidermoid carcinoma of salivary glands: A study of 69 cases with special attention to histologic grading. Am J Clin Path01 81:696, 1984