Crystal-storing histiocytosis with renal Fanconi syndrome: pathological and molecular characteristics compared with classical myeloma-associated Fanconi syndrome.

Background: Crystal-storing histiocytosis (CSH) is a poorly described complication of monoclonal gammopathy featuring histiocyte lysosomal storage of kappa light chain (kappa LC) crystals. Although CSH is usually associated with systemic manifestations, renal involvement is uncommon.

Methods: To investigate the molecular mechanisms implicated in kappa LC crystallization, we performed immunopathological and molecular studies in three patients with CSH and renal Fanconi syndrome (CSH/FS).