Abstract

An 81-year-old male presented with a 2-month history of erythematous plaques with scattered erythematous papules and hyperpigmentation on his right medial thigh. The patient’s medical history was positive for intertrigo in the groin and valvular heart disease, without associated immunosuppression. Clinically, intertrigo or inverse psoriasis were suspected due to the effected region and erythematous appearance. Punch biopsy demonstrated dense dermal granulomatous infiltrate composed of epithelioid histiocytes with granular eosinophilic cytoplasm. The histiocytes contained phagosomes with non-digested bacteria, which were shown to be gram negative rods on gram stain. Perls’ iron stain and PAS stain highlighted Michaelis-Gutmann bodies, a classic finding of malakoplakia. The patient was started on desonide 0.05% topical ointment and clobetasol 0.05% for itch relief. Malakoplakia is an acquired granulomatous disease that primarily impacts immunocompromised patients and can affect many organ systems, with the urogenital tract being the most common. Cutaneous findings are quite rare, but when they do occur the genital and perianal regions are frequently involved. While the mechanism of malakoplakia is not well understood, it is believed to be associated with opportunistic bacterial infections in an immunocompromised patient due to impaired macrophage activity following phagocytosis. Gram negative bacilli are frequently implicated in the pathology with E. coli being the most commonly identified organism. This case is unique in that the patient presented with sudden onset malakoplakia without a diagnosed immunocompromising condition or the use of immunosuppressive medications. His clinical course is actively being followed, with future treatments based on clinical progression and symptomatology.