Infection by human T-cell lymphotropic virus (HTLV-1) causes deregulation of the immune system, which makes the infected individuals more susceptible to infectious diseases. Immune deregulation is even more pronounced in HTLV-1 carriers with adult T-cell leukemia/lymphoma (ATLL), which results in frequent opportunistic infections. Hyalohyphomycosis is a rare subcutaneous mycosis which is more commonly associated with immunocompromised patients. We report a case of a HTLV-1-infected man with skin tumors, inguinal lymphadenomegaly, and lymphocytosis. Histopathological examination of skin biopsies revealed a T-cell lymphoma intermingled with a granulomatous process with abscesses and hyaline-septated hyphae. The lymph node showed only a T-cell lymphoma. The patient was diagnosed with acute ATLL and hyalohyphomycosis. He was treated with itraconazole for the subcutaneous mycosis and with chemotherapy for ATLL. A few months later, despite the treatment, he died because of progression of ATLL.