DERMATOFIBROMA WITH FOCAL NECROSIS AND GRANULAR CELL TRANSFORMATION
Granular cells similar to those found in granular cell tumors (granular cell schwannomas) are occasionally found in a variety of benign and malignant tumors including dermatofibromas, leiomyomas, and leiomyosarcomas. The granules in most of these cases consist of lysosomes and are PAS (periodic acid-Schiff) positive. The basic tumor type is determined by H&E stained sections with or without immunohistochemical studies.

Those dermatofibromas that I have seen that contained granular cells each had a history of trauma, and the granular cells were found near foci of necrosis. 


This tumor was located on the shoulder of an adult male. It had been recently traumatized. The specimen was received as fragments.
 
Figure 1. This is a very low power (direct scan of the glass slide) view of one of the fragments. Epidermal hyperplasia is seen over a spindle cell tumor.
Fig. 2. This is a very low power (direct scan of glass slide) view showing foci of necrosis and hemorrhage (pale, eosinophilic areas).
Medium power view from the fragment illustrated in Fig. 1. This appearance was typical of the bulk of the tumor. This tumor can be classified as a dermatofibroma based upon the histology of H&E stained sections. 
A medium power view from the fragment illustrated in Fig. 2. A focus of necrosis is seen in the left side of the picture. The spindle cells are very plump.
A very high power view of the above. An aggregate of eosinophilic granules (AG) is at the tip of the arrow. The aggregate has a halo around it and this type of structure is commonly found in granular cell tumors. 
A high power view from another area. Spindle cell morphology is more apparent in this picture. The granules are PAS positive (not illustrated). 

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