Tropical pyomyositis (TP) is an unusual infectious disease of skeletal muscles, caused by bacteria, and often associated with immunodeficiency conditions. The involvement of deep pelvic muscles, such as the iliac muscle, is even rarer. The association of systemic lupus erythematosus (SLE) and PT is seldom reported in the literature. Because SLE involves a state of immunosuppression resulting from both the disease itself and its medicamentous treatment, SLE patients are at higher risk for developing infections, such as PT. Infection by HTLV 1/2 is increasingly identified and associated with autoimmune diseases, such as SLE. This is a case report of PT in the pelvic muscles of a female patient with SLE, chronic kidney failure, on hemodialysis, and HTLV1/2 infection, admitted to the Hospital Heliópolis, in the city of São Paulo, Brazil.