e56 Arch Pathol Lab Med—Vol 127, January 2003 Pathologic Quiz Case—Senger et al

Pathologic Quiz CaseOvarian Mass in a 2-Year-Old Girl Presenting With Pleural Effusions

Christof Senger, MD; Leslie Diaz, MD; Howard Katzenstein, MD; Pauline M. Chou, MD

A2-year-old girl presented to her primary physicianwith increasing fatigue and decreasing appetite dur-

ing a 10-day period, and an abdominal mass was palpat-ed. Computed tomographic scan (Figure 1) performed atthe referring institution revealed a large retroperitonealtumor with prominent pelvic, abdominal, and mediastinalmasses associated with significant bilateral pleural effu-sions (right greater than left). Bone scan and skeletal sur-veys were negative for metastatic tumor. A 7-year-oldbrother had a history of congenital heart disease (ventric-ular septal defect) and omphalocele. Additional familyhistory was remarkable for breast and pancreatic cancer.The presumptive diagnosis was disseminated neuroblas-toma. The patient was transferred to our institution forfurther management. She was found to be in moderaterespiratory distress, and a right-sided thoracentesis wasperformed for both therapeutic and diagnostic purposes.Cytologic examination of the pleural fluid initially re-vealed a nonspecific malignant process, and the patientsubsequently underwent surgical exploration to obtain ad-ditional diagnostic material. Further workup of the cyto-logic specimen was performed concurrently.

Accepted for publication December 19, 2001.From the Departments of Pathology (Drs Senger, Diaz, and Chou)

and Hematology and Oncology (Dr Katzenstein), Children’s MemorialHospital, Chicago, Ill. Dr Senger is currently with The Hospital for SickChildren, Toronto, Ontario. Dr Diaz is currently with the University ofTexas M. D. Anderson Cancer Center, Houston, Tex.

Corresponding author: Pauline M. Chou, MD, Department of Pa-thology, Box 17, Children’s Memorial Hospital, Chicago, IL 60614 (e-mail: pmchou@northeastern.edu).

The tumor was observed intraoperatively as a mass em-anating from the right ovary and essentially replacing thenormal ovarian tissue. There was diffuse nodal diseaseand peritoneal implants as a result of transcelomic dis-semination, which were not appreciated radiographically.Intraoperative frozen section did not demonstrate histo-logic features suggestive of an epithelial or germ cell ori-gin.

Incisional biopsy specimens from the ovary and peri-toneal nodes confirmed the diagnosis subsequently ren-dered on the cytologic material alone, which was obtainedfrom the pleural effusions. A Papanicolaou-stained cytos-pin preparation revealed a highly cellular exudate com-posed of a mixture of cells (Figure 2). The backgroundconsisted of clusters of reactive mesothelial cells (doublearrow) and lymphocytes (single arrowhead). There werebizarre-appearing, discohesive giant cells, with pleomor-phic hyperchromatic nuclei (single arrow) and a variableamount of eosinophilic cytoplasm. Mitotic figures wereeasily identified (double arrowhead). Not infrequently, tu-mor cells show very vacuolated cytoplasm (inset). Figure3, A shows immunohistochemical stains for desmin, dem-onstrating cytoplasmic staining of paranuclear inclusion-like material. Figure 3, B shows an immunohistochemicalstain for myogenin, demonstrating nuclear positivity ofthe tumor cells in a characteristic diffuse fashion. Figure4 is a representative metaphase cytogenetic karyotype ofa tumor cell that has 94 chromosomes. A characteristictranslocation is highlighted by arrows. The presence of amessenger RNA transcript was confirmed by reverse tran-scriptase polymerase chain reaction.

What is your diagnosis?

Arch Pathol Lab Med—Vol 127, January 2003 Pathologic Quiz Case—Senger et al e57

e58 Arch Pathol Lab Med—Vol 127, January 2003 Pathologic Quiz Case—Senger et al

Pathologic Diagnosis: Alveolar Rhabdomyosarcoma,Solid Variant

Rhabdomyosarcoma, particularly the alveolar subtype,is one of the pediatric neoplasms that can present as adisseminated tumor in the neonatal period or early child-hood. It may be difficult, sometimes impossible, to deter-mine the anatomic site from which the tumor originated.It may be assumed that the origin is from the soft tissues.Tumors other than rhabdomyosarcoma that can presentas disseminated masses in the pediatric age group includethe generalized form of infantile myofibromatosis, neu-roblastoma, and hematopoietic neoplasms including lym-phomas. More recently, it has been recognized that malig-nant rhabdoid tumor characterized by abnormalities ofchromosome 22q11, arising from soft tissues, may alsopresent in neonates as disseminated tumor.1

This case was unusual for several reasons. The patientpresented with pleural effusions as a result of mediastinalinvolvement by tumor (primary mediastinal rhabdomyo-sarcomas not associated with a germ cell neoplasm havebeen reported before).2 In our case, the primary tumormost likely arose from the ovary and, notably, no associ-ated germ cell component was identified. Moreover, peri-toneal spread in a pseudomyxoma peritonei-like fashionwas present. This mode of spread is rather unusual andexpected in other neoplasms.

The frequency of intraperitoneal involvement of rhab-domyosarcomas at presentation is estimated to be about7%.3 Other tumors that can show peritoneal involvementin children include mesothelioma, desmoplastic smallround cell tumor, germ cell tumors (eg, gliomatosis peri-tonei), lymphoma, neuroblastoma, Wilms tumor, and in-tracranial tumors seeding via ventriculoperitonealshunts.3

Cytologic material from pleural, peritoneal, or pericar-dial fluids may be diagnostic in the pediatric population,and positive specimens, as summarized from a compre-hensive study,4 included lymphoma and leukemias (52%),neuroblastoma (14%), Wilms tumor (9%), gonadal and ex-tragonadal germ cell neoplasms (8%), bone and soft tissuesarcomas (7%), epithelial neoplasms (5%), Ewing sarcoma(2%), and other neoplasms (3%). Cytologic material frompleural, peritoneal, or pericardial fluid may yield materialsufficient for a definitive diagnosis of rhabdomyosarcoma,particularly when ancillary techniques are used. This iswell documented and includes, similar to our case, a re-port of a child presenting with massive pleural effusions.5Because they are not infrequently seen in rhabdomyosar-comas with effusions, vacuolated cells in effusions some-times confound the picture, since they are also suggestiveof a diagnosis of Burkitt lymphoma.

There are 4 histologic subtypes of rhabdomyosarcomasdescribed in children6: botryoid (accounting for 6% of alltumors), spindle cell (3%), embryonal (49%), and alveolar(31%). The corresponding 5-year survival rates were esti-mated at 95%, 88%, 66%, and 54%, respectively. Spindlecell type and botryoid type are included in the overallcategory of embryonal rhabdomyosarcoma. If alveolar fea-tures are present in any portion of the tumor, it is cate-gorized as alveolar rhabdomyosarcoma. Tumors withrhabdoid features are not classified as rhabdomyosarco-mas. The spindle cell type is confined to the paratesticularregion. The botryoid type is defined as a tumor growinginto hollow visceral structures in a polypoid fashion, ex-

plaining its predilection for sites in the head and neckregion and the genitourinary tract. Embryonal rhabdo-myosarcoma also favors the head and neck region. Alve-olar rhabdomyosarcoma is most often found in the ex-tremities or trunk.

The diagnoses of these tumors are typically establishedon morphologic grounds and confirmed by immunohis-tochemical analysis (myogenin and desmin in combina-tion are sufficiently specific). Embryonal rhabdomyosar-coma and alveolar rhabdomyosarcoma, solid subtype,sometimes show similar morphologic structure, and dis-tinction between them may be difficult. Younger childrenare more likely to have embryonal tumors in the head andneck or genitourinary tract, whereas alveolar tumors typ-ically occur in the extremities of older patients. Fortunate-ly, most tumors of the alveolar subtype display character-istic chromosomal changes, as seen in our case. There aretranslocations involving the forkhead domain region onchromosome 13, which encodes a transcription activatorin the forkhead domain region (FKHR). The most commontranslocations involve members of the PAX gene family(which are genes important as determinants of sequentialneural tube differentiation and segmentation during em-bryogenesis). The translocation t(2;13)(p36;q14), whichwas previously identified in the solid variant,7 involvesthe Pax3 gene on chromosome 2 and is found in morethan 60% of alveolar rhabdomyosarcomas. This wastrue for our case, and Figure 4 is a karyogram with thet(2;13)(p36;q14) highlighted by arrows. In our case, thereis also hyperdiploidy with an overall chromosome num-ber of 94 and presence of numerous double minutes. Atotal of 20 tumor cells were karyotyped, and the chro-mosome content ranged from 94 to 114 chromosomes.The t(2;13) involving the Pax3 gene is more frequentlyfound in a group of patients who are older, have truncaltumors, present with advanced stage, and typically havean inferior prognosis.8 Another common translocation ist(1;13)(p36¼4) involving the PAX7 gene on chromosome1,9 which is associated with a better prognosis.10 Currently,it is unclear if DNA content has specific diagnostic orprognostic implications and may be used as an indepen-dent predictor of survival.11 Ploidy may be correlated withhistologic subtype, and higher DNA contents are found inthe embryonal subtype. In general, hyperdiploidy (DNAindex 1.10–1.80) is found in patient groups with a betterclinical outcome compared with patient groups with ei-ther diploid or near-diploid or tetraploid or hypertetra-ploid tumors. The number of double minutes in our casevaried between 5 and 50. Double minutes in rhabdomyo-sarcomas may have negative prognostic implications. Onestudy identified multiple copies of the PAX7-FKHR fusiongene on a subset of double minutes and multiple copiesof the MYCN gene on other double-minute chromosomesin a rhabdomyosarcoma cell line.12

In conclusion, fluid cytologic material can be used toarrive at a proper diagnosis in the setting of rhabdomyo-sarcoma. Moreover, the abundant number of malignantcells that often present in these specimens can providematerial for additional complementary studies.

References1. White FV, Dehner LP, Belchis DA, et al. Congenital disseminated malignant

rhabdoid tumor: a distinct clinicopathologic entity demonstrating abnormalitiesof chromosome 22q11. Am J Surg Pathol. 1999;23:249–256.

2. Suster S, Moran CA, Koss MN. Rhabdomyosarcomas of the anterior medi-astinum: report of four cases unassociated with germ cell, teratomatous, or thymiccarcinomatous component. Hum Pathol. 1994;25:349–356.

Arch Pathol Lab Med—Vol 127, January 2003 Pathologic Quiz Case—Senger et al e59

3. Chung CJ, Fordham L, Little S, et al. Intraperitoneal rhabdomyosarcoma inchildren: incidence and imaging characteristics on CT. Am J Radiol. 1998;170:1385–1387.

4. Wong JW, Pitlik D, Abdul-Karim FW. Cytology of pleural, peritoneal andpericardial fluids in children: a 40 year summary. Acta Cytol. 1997;41:467–473.

5. Cohen I, Loberant N, King E, et al. Rhabdomyosarcoma in a child withmassive pleural effusion: cytological diagnosis from pleural fluid. Diagn Cyto-pathol. 1999;21:125–128.

6. Coffin CM, Dehner LP, O’Shea PA. Pediatric Soft Tissue Tumors. Baltimore,Md: Williams and Wilkins; 1997:214–253.

7. Parham DM, Shapiro DM, Downing JR, et al. Solid alveolar rhabdomyo-sarcoma with the t(2;13): report of 2 cases with diagnostic implications. Am JSurg Pathol. 1994;18:474–478.

8. Douglass EC, Rowe ST, Valentine M, et al. Alveolar rhabdomyosarcoma with

the t(2;13): cytogenetic findings and clinicopathologic correlations. Med PediatrOncol. 1993;21:83–87.

9. Biegel JA, Meek RS, Parmiter AH, et al. Chromosomal translocationt(1:13)(p36;q14) in a case of rhabdomyosarcoma. Genes Chromosomes Can-cer. 1991;3:480–484.

10. Kelly KM, Womer RB, Sorenson PH, et al. Common and variant genefusions predict distinct clinical phenotypes in rhabdomyosarcoma. J Clin Oncol.1997;15:1831–1836.

11. Niggli Powell JE, Parkes SE, et al. DNA ploidy and proliferative activity (S-phase) in childhood soft tissue sarcomas: their value as prognostic indicators. BrJ Cancer. 1994;69:1106–1110.

12. Frascella E, Lenzini E, Schafer BW, et al. Concomitant amplification andexpression of PAX7-FKHR and MYCN in a human rhabdomyosarcoma cell linecarrying a cryptic t(1;13)(p36;q14). Cancer Genetics Cytogenetics. 2000;121:139–145.