Can multiple myeloma present with skin lesions only?

Yes. However, it is extremely rare for myeloma to begin with only skin lesions. Extraosseous lesions in association with osseous myeloma are common, and the skin is one of the extraosseous sites. There are many skin diseases associated with monoclonal gammopathy, including pyoderma gangrenosum, scleromyxedema, scleroderma adultorum, leukocytoclastic vasculitis, collagen-vascular disease, xanthomas, Waldenström’s macroglobulinemia, subcorneal pustular dermatosis, pustular psoriasis, and even urticaria. The diagnosis of multiple myeloma is confirmed when there are lytic bone lesions, anemia, hypercalcemia, elevated serum and/or urine monoclonal protein spike, and bone marrow plasma cells exceeding 10%. Subcutaneous myeloma is much more common during late-stage, relapsed disease.

Requena L, Lutzner H, Palmedo G, et al: Cutaneous involvement in multiple myeloma: a clinicopathologic, immunohistochemical, and cytogenetic study of 8 cases, Arch Dermatol 139:475–486, 2003.