Dermatofibroma-like granular cell tumor

Background: There have been several reports in the literature of dermatofib romas with granular cells. Here we report a granular cell tumor with the ar chitecture of a dermatofibroma. This is the first report of this histologic al variant of granular cell tumor. The lesion was a 2.5-cm oval, hyperpigme nted plaque present for "years" on the back of a 60-year-old African-Americ an woman. Methods: The specimen was processed using formalin fixation and paraffin em bedding. Tissue sections were stained with hematoxylin and eosin. Immunohis tochemical studies were performed with antibodies directed against S-100 pr otein, neuron-specific enolase, and factor XIIIa. Results: Histopathologic examination revealed granular cells, some of which were spindle shaped, distributed singly and in small groups between collag en bundles resembling a dermatofibroma. Immunohistochemical studies showed the tumor cells to be positive for S-100 and neuron-specific enolase and ne gative for factor XIIIa. Conclusion: The immunohistochemical findings support the diagnosis of a gra nular cell tumor with a dermatofibroma-like pattern.