Cutaneous crystal storing histiocytosis: a report of two cases

Crystal storing histiocytosis (CSH) is a rare condition where crystals accumulate in the cytoplasm of macrophages and is usually associated with a lymphoplasmacytic neoplasm producing a monoclonal immunoglobulin with kappa light chain. CSH with primary manifestation in the skin is extraordinarily rare and limited to four case reports in the literature. Here we present two cases of cutaneous CSH. One case is that of an 80 year old woman who presented with bilateral periorbital oedema with yellow discolouration. Skin biopsy showed dermal CSH in association with a neoplastic lymphoplasmacytoid infiltrate showing IgM kappa light chain restriction. Subsequent work up led to the discovery of Waldenstrom's macroglobulinemia. She had an indolent clinical course but died 6 years later from transformation into a diffuse large B cell lymphoma in the bone marrow. The other case is that of a 52 year old man who was recently diagnosed with multiple myeloma and developed a pruritic rash on his back during chemotherapy. Skin biopsy showed Grover disease (transient acantholytic dermatosis) and crystal storing macrophages in the superficial dermis. He died 4 years later after a protracted clinical course involving multiple cycles of chemotherapy and numerous complications. In both patients cutaneous CSH occurred early in the course of their lymphoplasmacytic malignancy and its development did not herald rapid clinical decline.