Kaposi's sarcoma concurrent with granulomatosis polyangiitis.

Kaposi's sarcoma (KS), a malignant vascular tumor, can develop in patients who receive corticosteroids or immunosuppressive therapy. We report a patient with KS and granulomatosis polyangiitis (GPA). To the best of our knowledge, this is the first report regarding the co-occurrence of these two diseases. The physician must be aware of the risk of cancer in patients with rheumatism.