Malignant granular cell tumor.

We report a case of malignant granular cell tumor present in the left medial mid-thigh of a 69-year-old black male. The lesion was grossly fungating, partially ulcerated and measured 14 cm in largest diameter. Light microscopy, electron microscopy and immunohistochemistry techniques were used to confirm the preliminary cytologic diagnosis of malignant granular cell tumor. Diagnostic criteria of malignancy for such lesions are reviewed. Immunohistochemical and ultrastructural analyses support a neural or Schwann cell origin for the tumor. Clinical outcome for such lesions is discussed.