Malignant granular cell tumor: case report with a novel karyotype and review of the literature.

Malignant granular cell tumor is a rare neoplasm reported to occur at various sites in the body. Histogenesis of these tumors is still vaguely understood; however, their metastatic potential and adverse prognosis is well-described in the literature. The histologic criteria of malignancy proposed by Fanburg-Smith et al are still debatable amongst pathologists, with metastasis being the sole criterion of malignancy with unanimous agreement. To our knowledge, no specific karyotype characterizes these tumors. Hence, the importance of detecting characteristic cytogenetic alterations in these tumors which might serve, in the future, as a possible aid in diagnosis or therapy. We report a new case of malignant granular cell tumor of the thigh with metastases to abdominal wall and both lungs causing severe dyspnea. Cytogenetic analysis demonstrated that 60% of cultured tumor cells display the following karyotype 46,XX,+X,dic(5;15).