Cutaneous Involvement in Plasma Cell Myeloma

Clinicopathologic Findings in a Series of Ten Cases

Gauri Panse, MD; Antonio Subtil, MD; Jennifer M. McNiff, MD; Earl J. Glusac, MD; Christine J. Ko, MD; Anjela Galan, MD; Peggy Myung, MD, PhD; Mina L. Xu, MD


Am J Clin Pathol. 2021;155(1):106-116. 

In This Article

Abstract and Introduction


Objectives: Plasma cell myeloma (PCM) involving skin is rare and occurs in 1% to 4% of patients with PCM. We evaluated the clinicopathologic features, cytogenetic findings and clinical follow-up in a series of PCM cases with cutaneous involvement.

Methods: Cases of PCM with cutaneous involvement were retrospectively reviewed with clinical data.

Results: Skin involvement in PCM occurred in older individuals (mean, 75 years) and was more frequent in men (7/10 patients). All cases showed bone marrow involvement preceding the cutaneous lesions. Histopathologically, the infiltrate was plasmacytic (n = 5) or primitive or plasmablastic (n = 4), and 1 case showed predominantly lymphoplasmacytic features with cyclin D1 immunoreactivity and CCND1 gene rearrangement. Concurrent amyloid deposition was seen in one biopsy, and another case demonstrated coexisting squamous cell carcinoma. The most common immunophenotype was CD138+, CD20–, and CD56+ with light chain restriction. Cytogenetic analysis (available for 7 cases) showed multiple hyperdiploid abnormalities. Follow-up was available for 8 cases (mean, 42 months; range, 11–156 months) and showed short-term disease-related death in 7 of 8 patients.

Conclusions: Cutaneous involvement in PCM demonstrates a diverse cytomorphologic spectrum with plasmacytic, plasmablastic, or lymphoplasmacytic features and may show concurrent amyloid deposition or neoplasms such as squamous cell carcinoma. Cutaneous involvement typically occurs late in the course of the disease and likely portends poor outcome.


The vast majority of plasma cell myeloma (PCM) cases are confined to bone marrow (BM), with lytic bone lesions being the most common manifestation of the disease. Extramedullary secondary cutaneous dissemination is relatively infrequent and has been reported to occur in 1% to 4% of PCM.[1,2] We present a series of 10 cases of PCM involving skin that are from a single institution, and we discuss the clinical and histopathologic features, including novel findings.