Three cases of sclerosing lipogranuloma: an immunohistochemical study.

Sclerosing lipogranuloma (SLG) is a rare disease that occurs in the male genital region. We report here three cases of SLG, including two of Y-shaped lesions in the penile base forming an intrascrotal mass, as well as a patient with a mass in the epidydimal region. All three lesions histologically exhibited formation of multiple granulomas consisting of multinucleated giant cells and epithelioid cells, in the fibroadipose tissue or around the epidydimis, in association with eosinophil infiltration. Membranocystic changes were found within the cytoplasm of multinucleated cells. In the two patients with scrotal lesions, membranocystic changes were positive for diastase-PAS reaction and on Sudan black B staining in dewaxed sections. CD68 staining was strongly positive in multinucleated giant cells and epithelioid cells. Most of the lymphocytes infiltrating the lesions were T cells associated with some S-100-positive dendritic cells. T-cell mediated immune reaction appears to be important in the histogenesis of SLG. The histogenesis is generally considered to be a foreign-body reaction to degenerated or damaged fatty tissue or lipids, but no apparent causative factors can be identified in some reported cases. All three patients in the present study had a good clinical course after biopsy or surgical excision. We thus report three cases of SLG including an unusual case in the epidydimal region, with some considerations regarding the histogenesis of SLG.