Histoplasmosis is a systemic disease caused by Histoplasma capsulatum, a dimorphic fungus. It is prevalent in several regions worldwide, particularly in the Americas, where it is a significant opportunistic infection in people living with HIV. Transmission occurs via inhalation of microconidia released during activities in contaminated soil, especially in areas with bird or bat droppings. Clinical manifestations are highly variable and often involve the head and neck region.

A 39-year-old man presented with a progressively enlarging nasal lesion over six months, associated with nasal obstruction and rhinorrhea. He denied other symptoms. Examination revealed a vegetative lesion approximately 4 cm in size with crusting, exudate, and purulent discharge, causing nasal deformity and destruction of the alae, tip, and columella. He was hospitalized for investigation and treatment. Serology confirmed anti-HIV reactivity, and a urinary histoplasmosis antigen test was positive. An incisional biopsy revealed yeast forms suggestive of histoplasmosis on Grocott staining. Cultures from nasal and oral lesions supported the diagnosis. Additional tests showed an HIV viral load of 228,000 copies/mL and a CD4+ T-lymphocyte count of 6 cells/µL, indicating severe immunosuppression. Liposomal amphotericin B (3 mg/kg/day) was initiated, with a favorable response.

Isolated mucocutaneous presentations of histoplasmosis are rare and usually indicate disseminated disease. Skin lesions may present as papules, plaques, nodules, or ulcers, while mucosal involvement commonly affects the oral, pharyngeal, or laryngeal cavities, appearing as leukoplastic, ulcerated, or proliferative lesions. Differential diagnoses include carcinoma, lymphoma, and infections such as leishmaniasis, paracoccidioidomycosis, sporotrichosis, syphilis, and cutaneous tuberculosis. Proven diagnosis is obtained by fungal isolation from clinical samples such as biopsies. Urinary antigen detection is a highly sensitive and specific screening method, particularly in immunocompromised patients. Histoplasmosis has significant lethality, reaching up to 40% among people living with HIV in Latin America. The treatment of choice for moderate to severe disease is liposomal amphotericin B, followed by a prolonged maintenance course with itraconazole.