Superficial Hemosiderotic Angiomyxoma

Abstract

A case of superficial angiomyxoma presenting as a pigmented nevus on the shoulder of a 77-year-old man is described. Histologically, the lesion was unencapsulated and demonstrated numerous small, bland, bipolar spindle cells embedded in a vascular, mucinous stroma. The lesion was also characterized by extensive, perivascular collections of large macrophages with foamy cytoplasm and extensive intracellular deposition of granular, golden-brown pigment consistent with hemosiderin. The iron stain was strongly positive. These phagocytic cells stained positively for vimentin and Ham 56, supporting a macrophage lineage. Hemosiderin was also noted within the cytoplasm of the spindle cells in the angiomyxomatous component; these spindle cells expressed factor XIIIa, CD34, or both, and thus likely represented dermal dendritic cells with phagocytic properties. Numerous hemosiderinladen macrophages in cutaneous angiomyxoma, possibly a result of occult trauma, result in a distinctive histologic appearance and may result in clinical resemblance to a melanocytic nevus.