Generalized Acquired Cutis Laxa Associated With Multiple Myeloma With Biphenotypic IgG-λ and IgA-κ Gammopathy Following Treatment of a Nodal Plasmacytoma

Background: Cutis laxa is a rare dermatosis that can be inherited or acquired. The acquired form is rare and has been associated with various conditions, including multiple myeloma, monoclonal gammopathy of undetermined significance, and heavy chain deposition disease. Observations: We describe a 48-year-old man who developed generalized cutis laxa over a 4-year duration. There were no preceding skin changes except for a history of erythematous plaques with granuloma annulare-like features on his buttocks and lateral hips. He underwent treatment of an axillary lymph node plasmacytoma with surgery and radiation 4 years prior to his cutaneous changes and had been clinically monitored with a diagnosis of monoclonal gammopathy of unknown significance (MGUS). Cutaneous manifestations prompted a systemic evaluation demonstrating a persistent monoclonal IgG-lambda M-spike on immunofixation electrophoresis and lytic bone lesions. He was later found to have biphenotypic IgG-lambda and IgA-kappa multiple myeloma. Conclusions: Multiple myeloma, plasma cell dyscrasia, and heavy-chain deposition disease have been very rarely reported to be associated with acquired cutis laxa (ACL). Findings in our patient support the hypothesis that paraproteinemia is a cause of ACL through immunologic destruction of elastic fibers manifesting as granuloma annulare-like plaques. Evaluation for an underlying gammopathy is essential for the workup of a patient with new-onset ACL.