Increased Risk of Cutaneous Diseases in Multiple Myeloma Patients.

Introduction Multiple myeloma (MM) is a monoclonal gammopathy characterized by malignant proliferation of plasma cells in the bone marrow, leading to the overproduction of monoclonal immunoglobulins. Knowledge of cutaneous findings associated with multiple myeloma is limited. This study aims to characterize cutaneous manifestations in patients with MM or monoclonal gammopathy of undetermined significance (MGUS). Methods This is a retrospective study of patients seen at a single institution between January 2000 and January 2019 with a diagnosis of "multiple myeloma," "monoclonal gammopathy of undetermined significance," or "smoldering myeloma," and an on-site dermatology clinic visit. Results Twenty patients met the inclusion criteria. Most patients were male and Caucasian. Comorbid cutaneous malignancies were noted in 65% of patients (n = 13). Basal cell carcinoma (BCC) was characterized in 55% of patients (n = 11), followed by squamous cell carcinoma in 50% of patients (n = 10), and melanoma in 10% of patients (n = 2). Conclusions Patients with monoclonal gammopathy may be predisposed to developing cutaneous malignancies and skin infections. Given the low prevalence of monoclonal gammopathy, larger multi-center studies with a control cohort may be necessary to delineate the significance of these comorbid skin conditions.