Benign fibrous histiocytoma of prepuce in the mule

Here we present a case of preputial benign fibrous histiocytoma in a seven-year-old mule. This case was treated surgically. Pathologic analysis and diagnosis of these lesions were based on a combination of light microscopy and immunohistochemistry. Histologically, the tumor was composed primarily of prevalent storiform pattern of fibroblastic and poligonal cells. Immunohistochemistry, except for consistent immunoreactivity for vimentin, nearly all tumor cells were positive for CD68, S-100 protein, pan-cytokeratin, alfa-smooth muscle actin, and desmin. Benign fibrous histiocytoma of the prepuce in mule is rarely reported in the veterinary literature.