A case of metastatic non-neural granular cell tumor in a 13-year-old girl.

Conventional granular cell tumor represents a mesenchymal neoplasm observed in a variety of locations and is now believed to be of Schwann cell origin. Granular cell change has also been observed in a variety of different tumors, but recently described in the skin has been a distinct entity termed non-neural granular cell tumor, which lacks expression of S100 protein and is of uncertain histogenesis. This tumor typically displays a greater degree of nuclear atypia and mitotic activity than conventional granular cell tumor but appears to behave in a relatively benign fashion, as only two previous instances of lymph node metastasis have been documented. Herein, we report a case of non-neural granular cell tumor arising on the back of a 13-year-old girl, and later axillary lymph node metastasis with extracapsular extension was observed.