IgA/kappa-restricted crystal storing histiocytosis involving the central nervous system characterized by proteomic analysis.

Crystal storing histiocytosis (CSH) is a rare disorder characterized by the accumulation of crystalline material in the cytoplasm of histiocytes. Involvement of the central nervous system (CNS) with CSH is extremely rare. Herein, we report a case of crystal storing histiocytosis involving the CNS. Using immunohistochemistry and mass spectrometry we demonstrate that the disease resulted from an IgA-κ restricted plasma cell dyscrasia. CNS-CSH represents a rare clinicopathologic entity with an indolent course, usually lacking systemic manifestations.