Embryonal Rhabdomyosarcoma of the Urinary Bladder: A Case Report

Embryonal rhabdomyosarcoma accounts for 4.5% of the childhood cancers. Rhabdomyosarcoma is the most common malignant soft tissue sarcoma in children and has the following subtypes: embryonal, alveolar, pleomorphic and spindle cell/sclerosing. About 17% of rhabdomyosarcomas occur in genito-urinary tract. A 2-year-old male child presented with complaints of excessive crying while passing urine and dribbling of urine for 1 day. Patient underwent cystoscopic biopsy and histopathological examination was done after taking written consent by the parents following which showed a cyst arising from bladder neck extending into right lateral wall of prostate. Partial excision of the cystic lesion was done. Gross examination of the biopsy revealed multiple grey-white to grey-brown soft tissue bits largest measuring 2cms in length and smallest measuring 0.2cm in length. Microscopy revealed a malignant neoplasm composed of poorly differentiated tumor cells arranged in sheets. Individual cells are primitive ovoid to spindle shaped with moderate pleomorphism and hyperchromatic nuclei with minimal cytoplasm admixed with myxoid areas. Few scattered Rhabdomyoblast like elongated cells with cytoplasmic eosinophilia and sparse atypical mitosis noted. Cambium layer was seen. Margin status were not assessed as the specimen was received in piece meal. Differential diagnosis of small round blue cell tumor was considered. Immunohistochemistry showed positivity for smooth muscle Actin, Desmin, Myogenin and MyoD1 suggesting Embryonal Rhabdomyosarcoma. Embryonal Rhabdomyosarcoma is the most common subtype of pediatric rhabdomyosarcoma. Age, Stage at diagnosis and treatment received are the predictors of the survival of Embryonal RMS.