Malignant Ectomesenchymoma in a Two-Month-Old Boy

ABSTRACT

Malignant ectomesenchymoma is a rare tumor originating from remnants of migratory neural crest(ectomesenchyme) and composed of neuroectodermal as well as mesenchymal components. Neuroblasts and ganglion cells constitute the neuroectodermal components and rhabdomyosarcoma is the most frequently encountered mesenchymal components. We report a case of malignant ectomesenchymoma in a two-month-old boy who was presented with abdominal pain and urinary difficulty. The tumor appeared to arise from the prostatic region and enlarged to compress the bladder leading to bilateral hydronephrosis. Immunohistochemical studies for the resected tumor confirmed the presence of mixed ganglioneuroma and rhabdomyosarcoma establishing the diagnosis of malignant ectomesenchymoma. However, in the initial biopsy specimen of tumor, poorly differentiated round to oval cells positive for both desmin and vimentin staining were uniformly noted and the incorrect diagnosis of rhabdomyosarcoma was made. Intensive multi-agents chemotherapy, surgery and radiotherapy had failed in preventing the development of local recurrences. Subsequently, invasion of pubic bone and lung metastases ensued. This report enlightens the need for immunohistochemistry to seek possible neuroectodermal components in a tumor specimen suggestive of rhabdomyosarcoma.