Cryocrystalglobulinemia-An Uncommon Cutaneous Presentation of Multiple Myeloma and Novel Finding of Transepidermal Elimination of Crystals

Abstract

Cryocrystalglobulinemia (CCG) is a rare subset of type 1 cryoglobulinemia that is classically associated with an underlying paraproteinemia. The cryocrystalglobulins are characterized by extracellular crystals, which are eosinophilic, periodic acid-Schiff positive, and exhibit nonbirefringence under polarized light. This archetypal appearance renders CCG readily diagnosable histologically. Unlike in mixed cryoglobulinemias (types II and III cryoglobulinemia) where there is complement-mediated inflammation amounting to vasculitis, the deposition of crystallized paraproteins within vessels in CCG result in an occlusive vasculopathy and culminate in severe systemic involvement. Aside from cutaneous lesions, the resultant ischemic hypoperfusion manifest frequently with fulminant acute kidney failure, polyarthralgia, peripheral neuropathy, or gastrointestinal ulceration, conferring a poor prognosis. We present an unusual case of a patient diagnosed with immunoglobulin G kappa multiple myeloma that first presented with cutaneous necrosis as a result of CCG and did not have any renal impairment or fatal outcome. We highlight this uncommon entity to underscore the clinical importance of early diagnosis to avoid significant morbidity and mortality. In addition, we also discuss a novel feature of transepidermal elimination of crystalline precipitates demonstrated on his skin biopsy.