Factor XIIIa Expression in Pseudo-Kaposi Sarcoma

A 39-year-old man had pseudo-Kaposi sarcoma on his left foot. A biopsy specimen obtained from a cutaneous lesion showed increased numbers of vascular spaces, proliferation of fibroblast-like spindle cells, and deposition of hemosiderin in the dermis. Immunohistochemically, proliferative fibroblast-like spindle cells around the vessels were positive for anti-factor XIIIa antibody. Excessive heat radiation was detected from the skin lesions by thermography.