Intravascular crystal deposition: an early clue to the diagnosis of type 1 cryoglobulinemic vasculitis.

Cutaneous small vessel vasculitis (CSVV) is a nonspecific finding with an extensive differential diagnosis. It is critically important to distinguish skin-limited presentations of CSVV from severe life-threatening systemic vasculitides presenting with CSVV as an initial manifestation. It can be challenging to determine which patients presenting with CSVV are at risk for systemic disease. Standard histopathologic evaluation, direct immunofluorescence, and serologic evaluation is typically required to exclude a systemic vasculitis. Type 1 cryoglobulinemia may rarely present with CSVV. Herein, we report a case of type 1 cryoglobulinemia in the setting of occult multiple myeloma. CSVV with prominent intravascular crystal formation was noted. The presence of intravascular crystals in the setting of CSVV may represent an important early clue to the diagnosis of type 1 cryoglobulinemic vasculitis.