Track

Clinical Studies

Abstract

Dermatofibroma is a common benign cutaneous neoplasm composed of variable combinations of fibroblastic cells, histiocytes, and coarse collagen fibers. The aneurysmal/hemosiderotic subtype (ADF/HDF) has characteristic pseudo-vascular spaces with hemosiderin-laden histiocytes and reactive spindled and epithelioid cells. Both grossly and microscopically, these subtypes can share features with melanoma and vascular tumors, sometimes necessitating the use of other tools to appropriately differentiate these entities. Fontana-Masson special stain for melanin has not previously been investigated in ADF/HDF. 

Retrospective chart review identified cases of aneurysmal or hemosiderotic dermatofibroma (ADF/HDF). These were then stained with Fontana-Masson stain and SOX-10 or S100 protein and evaluated by two board-certified dermatopathologists. 

A total of 79 cases were included, 48 females and 31 males aged between 12 and 84 years. The most common location of aneurysmal or hemosiderotic dermatofibroma was the lower. Ninety-five percent of aneurysmal dermatofibroma and ninety-eight percent of hemosiderotic dermatofibroma cases were positive for Fontana-Masson melanin stain. SOX-10 or S100 protein stain was negative in all cases. 

This study demonstrates that ADF/HDF stain with Fontana-Masson suggesting a melanin component to these dermatofibroma subtypes. These findings suggest that the majority of ADF/HDF contain melanin pigment and Fontana-Masson should not be used to differentiate melanocytic neoplasms from ADF/HDF.