Crystal-storing histiocytosis and immunocytoma associated with multifocal fibrosclerosis.

Aims: Crystal-storing histiocytosis is a rare disorder described in patients with lymphoproliferative diseases, mainly in cases of multiple myeloma but also in lymphoplasmacytic lymphoma (immunocytoma). Most cases involve one single organ which, in the majority, is related directly to the presence of tumour. We describe a 44-year-old man with a clinical picture of multifocal fibrosclerosis (with mesenteric panniculitis, peritoneal, mediastinal and orbital fibrosis) in which the autopsy showed a systemic infiltrate of crystal-storing histiocytes and functional alteration of the organs involved, associated with IgG-kappa type immunocytoma.
Methods and Results: Histology showed a systemic infiltration, with a predilection for adipose tissue, by a diffuse cellular infiltrate composed of small lymphocytes, plasmacytoid lymphocytes and plasma cells, admixed with large number of crystal-storing histiocytes. Intracytoplasmic crystals were not identified either in the plasma cells or plasmacytoid lymphocytes. The neoplastic cells and the crystalline inclusions displayed reactivity with antibodies for IgG and the kappa light chain. A polymerase chain reaction study for the IgH gene showed a monoclonal rearrangement. Ultrastructural studies showed needle-shaped crystals surrounded by a single unit membrane.
Conclusion: This case is, to the authors' knowledge, the first to be described in which crystal-storing histiocytosis is associated with a clinical picture of multifocal fibrosclerosis, which suggests that lymphoproliferative processes should be considered in the differential diagnosis of the various conditions associated with multifocal fibrosclerosis.