Prevalence and clinicopathologic characteristics of multiple myeloma with cutaneous involvement: A case series from Korea

Background: Multiple myeloma (MM) is a plasma cell dyscrasia characterized by the presence of a clonal proliferation of tumor cells. Cutaneous involvement of MM is very rare and remains poorly understood. Objective: The aim of this study was to examine the clinical and histopathologic characteristics of cutaneous involvement in MM and identify factors associated with overall survival of MM with cutaneous involvement. Methods: The medical records of 1228 patients with MM were retrieved and analyzed. Of those patients, 14 with cutaneous involvement of MM (1.14%) were further evaluated for their clinical and histopathologic findings. Results: Patients with cutaneous involvement showed significantly reduced overall survival compared with those without cutaneous involvement (median, 28 vs. 57 months; hazard ratio, 1.929; 95% confidence interval, 1.030-3.613). In subgroup analyses of patients with MM with cutaneous involvement, erythematous nodules (P =.004), multiple cutaneous lesions (P =.002), and absence of a grenz zone (P =.004) were clinicopathologic features associated with reduced overall survival after Bonferroni correction. Limitations: The retrospective design and the small sample size are the limitations. Conclusion: Cutaneous involvement accounted for about 1.14% of patients with MM and was associated with reduced overall survival.