Intravascular immunoglobulin crystalloids in monoclonal cryoglubulinemia‐associated dermatitis: ultrastructural findings

Abstract

A 46-year-old woman developed polyarthritis, purpuric skin rashes, nasal septal perforation and marginal furrowing of corneas in 1980. Monoclonal IgG, kappa cryoglobulinemia was found in the patient's serum. No underlying lymphoproliferative disorder has been found in ten years since her original diagnosis. In 1991, she developed palpable purpura on both lower extremities with subsequent necrosis and ulceration. A skin biopsy revealed fibrin thrombi within capillaries in the papillary dermis, and immunofluorescence studies showed IgG and light chain kappa within the fibrin thrombi. An electron microscopy study showed intravascular immunoglobulin crystalloid structures with a mean diameter of 80.3A degrees (8.03 nm), mixed with fibrin and red blood cells. The exclusive vascular location of these crystalloids may have implication in the pathogenesis of skin lesions.