Acquired cutis laxa associated with heavy chain deposition disease involving dermal elastic fibers.

IMPORTANCE Acquired cutis laxa is a rare cutaneous manifestation of hematologic malignancy. We report a case of γ heavy chain deposition disease (HCDD) associated with acquired cutis laxa, renal involvement, and hypocomplementemia and propose a mechanism of elastic fiber degradation in the skin of this patient with HCDD. OBSERVATIONS To determine the localization of immunoglobulin heavy chains and complement activation in the skin of a patient with HCDD, we examined her skin biopsy specimens under light and electron microscopy. Analysis demonstrated the deposition of γ heavy chain and complement components C1q and C3 on the surfaces of dermal elastic fibers, indicating complement fixation by the deposited heavy chains. Electron microscopy revealed finely granular electron-dense deposits coating the surfaces of frayed dermal elastic fibers. CONCLUSIONS AND RELEVANCE The pathogenesis of cutis laxa in this condition is poorly understood. We hypothesize a mechanism of elastic tissue destruction by complement fixation with resultant activation of the complement cascade ultimately causing elastolysis. Based on our findings and those of other reports, we propose that skin heavy chain deposition can serve as a marker of plasma cell secretory activity in HCDD, although further studies are needed.