LETTER TO EDITOR
Year : 2010 | Volume
: 53 | Issue : 1 | Page : 167--168
Alveolar rhabdomyosarcoma of vulva
Rekha B Puranik, Sujatha Naik, Shridhar Kulkarni, MH Kulkarni
Department of Pathology, Karnataka Institute of Medical Sciences, Hubli, India
Rekha B Puranik
Department of Pathology, Karnataka Institute of Medical Sciences, Hubli
|How to cite this article:|
Puranik RB, Naik S, Kulkarni S, Kulkarni M H. Alveolar rhabdomyosarcoma of vulva.Indian J Pathol Microbiol 2010;53:167-168
|How to cite this URL:|
Puranik RB, Naik S, Kulkarni S, Kulkarni M H. Alveolar rhabdomyosarcoma of vulva. Indian J Pathol Microbiol [serial online] 2010 [cited 2023 Sep 21 ];53:167-168
Available from: https://www.ijpmonline.org/text.asp?2010/53/1/167/59218
Rhabdomyosarcoma (RMS) in general is the most common soft tissue sarcoma in children under 15 years of age and one of the most common soft tissue sarcoma of adolescents and young adults. They are most commonly found in the head and neck region (44%) followed by paratesticular region and retroperitoneum (20.4%) and extremities (14.6%). Among the histological types, alveolar rhabdomyosarcoma tends to affect older patients with a peak in 10-25 years with a predilection for deep soft tissues of the extremities. Its occurrence in vulva and vagina accounted for only 0.9% in armed forces institute of pathology (AFIP) series of 558 cases.  We report a rare case of alveolar RMS of vulva.
A 17-year-old girl presented with history of mass in the vulva of four months duration [Figure 1]; no other local or systemic symptoms were present. Fine needle aspiration cytology (FNAC) of the mass showed a cellular aspirate with small round cells arranged in singles and small groups. The cells had scant cytoplasm and a large hyperchromatic nucleus and some showing prominent nucleoli. An impression of malignant small round cell tumor was made. Ultrasonographic examination showed growth involving anterior wall of vagina and reaching the bladder wall. Surgical biopsy was done with wide excision of the tumor and perineal tissue. Grossly, a grey white well circumscribed tumor with a nodular surface was seen beneath the skin measuring 7cm X 6cm x5cm. Microscopy showed tumor cells arranged in sheets, trabeculae and alveolar pattern separated by thin fibrous septae to which cells were adherent [Figure 2]a. Cells were small round to oval, slightly pleomorphic and with scant cytoplasm, hyper chromatic nuclei and prominent nucleoli. Mitotic figures were in plenty. Occasional tumor giant cells were seen [Figure 2]b. Overlying skin was free from tumor. Perineal tissue showed infiltration with tumor cells [Figure 2]c. Diagnosis of RMS, alveolar type was made; the same was confirmed by immunohistochemistry (IHC) with diaminobenzidine (DAB) stain, as the tumor cells were positive for desmin [Figure 3]a, weakly positive for myoglobin [Figure 3]b and negative for Myo-D1. The case was lost to follow-up.
Copenland,  reported eight cases of alveolar rhabdomyosarcoma (ARMS) of female genitalia with two cases occurring in vulva predominantly in the adolescent age group. Imachi et al.  also reported two cases in vulva. They noted that it presents either as a painless or mildly tender mass. Several authors have reported the cytological findings in RMS. Orell  mentions that aspirations from these tumors are highly cellular with a consistent pattern of small cell tumor with predominantly single cells or stripped nuclei; cells are mainly uniform with rounded or irregular nuclei and scanty cytoplasm. Chromatin is variably coarse and nucleoli may be prominent. Alveolar or rosette-like structures may be seen. However, multinucleated cells are not a common finding. ARMS has a specific chromosomal aberration demonstrable with molecular genetic methods .Immunocytochemical demonstration of desmin is valuable in confirming the diagnosis.  Knowledge of age range and specific site of predilection will help in correct identification.  However, FNAC is an important preliminary diagnostic modality. FNAC in our case showed good cellularity with fairly monomorphic cells having scant eosinophilic cytoplasm and hyperchromatic nuclei with prominent nucleoli in some. Cross striations were not observed either in smears or sections. However, focal alveolar pattern in histopathological sections was suggestive though not diagnostic. IHC confirmed the same.
Tumors that lack cross striations need to be differentiated from other small blue round cell tumors like Ewing's sarcoma/ peripheral primitive neuroectodermal tumor, poorly differentiated adenocarcinoma, malignant lymphoma and neuroblastoma. Histologically, absence of neuro fibrillary background and rosette pattern does not suggest neuroblastoma. Tumor cells in Ewing's sarcoma are more uniform, may show periodic acid Schiff (PAS) positive cytoplasmic granules and are seen in sheets with areas of necrosis; giant cells are not usually seen. An ill defined acinar pattern may be observed in poorly differentiated adenocarcinoma; malignant lymphoma also has undifferentiated appearance of round cells. IHC is essential in tumors that show poor cytological differentiation.  Desmin is the best single marker for RMS cells as it is consistently present. Myoglobin, though a specific marker of skeletal muscle tumors, is restricted to more differentiated rhabdomyoblasts and generally absent in primitive round cells.  Myo-D1, a nuclear antigen typical of cells of striated muscle lineage, apparent in primitive tumor cells is a sensitive and specific marker for RMS. 
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