Abstract Lobomycosis is a chronic granulomatous infection caused by the yeast Lacazia loboi, typically found in tropical and subtropical geographical areas. Transmission occurs through traumatic inoculation into the skin, especially in exposed areas, of men who work in contact with the soil. Lesions are restricted to the skin and subcutaneous tissue, with a keloid-like appearance in most cases. The occurrence of squamous cell carcinoma on skin lesions with a long evolution is well known; however, there are scarce reports of lobomycosis that developed into squamous cell carcinoma. The authors report a patient from the Brazilian Amazon region, with lobomycosis and carcinomatous degeneration, with an unfavorable outcome, due to late diagnosis.