Figure 7.

Representative photomicrographic images of perianal melanoma biopsy samples obtained from a mature, gray horse before (A) and after a series of 3 H-FIRE treatments (B). In (A), the tumor is composed of a pleomorphic population of variably-sized polygonal cells. Cells range from small round cells with sparse pigmentation to larger, more heavily pigmented cells, with brown-dark brown intracellular pigment in fine cytoplasmic granules. There are small nesting clusters of some melanocytic cells, typical of melanocytic neoplasms. Mitotic figures are uncommon, as are cells undergoing degeneration. (HE × 400). In B, treatment with H-FIRE has disrupted cells, releasing pigment, and has created zones of ablation and replacement fibrosis (HE × 200).