[Cutaneous malacoplakia. An immunohistochemical and ultrastructural case study].

The authors report a case of a 70 year-old man with a past of myelodysplasia and presenting a voluminous lesion of the thigh corresponding to a cutaneous malacoplakia. Histologic study showed a dermo-hypoderma granuloma with numerous Von Hansemann cells containing some Michaelis-Gutmann bodies. Immunohistochemical study showed a positivity of these cells with the antibodies against CD68 (KP1, Mac 387, PGM1), the lysozyme and the alpha-chemotrypsine. Ultrastructural study confirmed the histiocytic origin of this infiltration by showing some regular and voluminous inclusions with a clear center and a peripheral and dense ring, and also some bacteria measuring 3 to 5 microns. Bacteriological study isolated an Escherichia coli. The evolution was favourable after surgical excision and antibiotherapy. Cutaneous malacoplakia is a very rare disease, usually with a perineal localization, and occurring in immunodeficient host. Michaelis-Gutmann bodies are sometimes difficult to identify by light microscopy underlying the rule of the immunohistochemical and the ultrastructural studies to perform the diagnosis.