Case of multiple myeloma associated with extramedullary cutaneous plasmacytoma and pyoderma gangrenosum

A variety of cutaneous manifestations has been described in multiple myeloma including extramedullary cutaneous plasmacytomas, cutaneous amyloidosis, pyoderma gangrenosum, leukocytoclastic vasculitis, necrobiotic xanthogranuloma, scleromyxedema, Sweet's syndrome, subcorneal pustular dermatosis, scleredema, and plane xanthomas etc. An 89-year-old Korean man, who had been suffering from multiple myeloma 1 year previous, presented for evaluation of two nodules on the right side of the forehead, left side of the chest (7th rib area), and multiple ulcers with papulopustules on both the thigh and the left side of the chest (2nd rib area) during 15 days, which developed at the same time. A biopsy of a lesion which manifested as a cutaneous nodule on the right side of the forehead revealed dermal infiltration by well-differentiated plasma cells, similar to those found on a bone marrow biopsy, and a biopsy of the lesion manifested as a painful ulceration on the right thigh area showing dermal neutrophilic infiltration. Histologic findings were consistent with plasmacytoma and pyoderma gangrenosum, respectively. We present a case of multiple myeloma which developed extramedullary cutaneous plasmacytoma and pyoderma gangrenosum simultaneously, which is very rare. The patient was treated with a systemic steroid and conservative therapy.