Atypical Cutaneous Presentation of Waldenström Macroglobulinemia: An Extensive Erythematous Patch Mimicking an Angiosarcoma

Waldenström macroglobulinemia (WM) is an immunoglobulin M–producing lymphoproliferative disorder in elderly individuals. Cutaneous manifestations of WM are rare and typically consist of plaques or nodules. We describe a case of a man with WM who presented with an extensive erythematous patch on the scalp that clinically mimicked an angiosarcoma.