PRIMARY CUTANEOUS EWINGS-SARCOMA PERIPHERAL PRIMITIVE NEUROECTODERMALTUMORS IN CHILDHOOD - A MOLECULAR, CYTOGENETIC, AND IMMUNOHISTOCHEMICAL STUDY

Childhood cutaneous and subcutaneous malignancies are rare and include metastatic tumors of diverse histogenesis as well as primary lesions, such as sweat gland carcinomas. Some cutaneous malignancies exhibit a small round cell tumor morphology with few definitive differentiating features; they can thus pose a significant diagnostic problem. We des cribe two primary malignancies of the skin and superficial subcutis, w hich were originally diagnosed as sweat gland carcinomas on the basis of their morphological features. A cytogenetic analysis performed on o ne of these lesions showed the t(11;22)(q24;q12) rearrangement, believ ed to be unique to the Ewing's sarcoma/ peripheral primitive neuroecto dermal tumor (ES/pPNET) group of neoplasms. In view of this unexpected result, reverse transcriptase-polymerase chain reaction analysis was performed on both lesions and showed that they expressed EWS/FLI-1 fus ion gene mRNA transcripts, the molecular equivalent of t(11;22)(q24;q1 2). The two tumors also had an immunohistochemical profile suggesting ES/pPNET, including strong expression of the MIC2 antigen. Both patien ts were treated with wide local excision, and one was given a course o f chemotherapy. Neither patient showed evidence of tumor elsewhere aft er follow-up periods of 2 years and 16 years. These findings suggest t hat these tumors are indeed a form of primary ES/pPNET arising in the skin or superficial subcutis, which may be of low-grade malignancy and curable by local surgery.