Multiple myeloma with crystal-storing histiocytosis, crystalline podocytopathy, and light chain proximal tubulopathy, revealed by retinal abnormalities A case report

Rationale: Crystal sorting histiocytosis (CSH) is a rare disorder that is morphologically characterized by the accumulation of monoclonal immunoglobulin crystals, predominantly of a kappa light chain type, within lysosomes of macrophages. CSH may result in a variety of clinical manifestations depending on the involved organs. In this case report, we aim to describe a patient with ophthalmic manifestations which lead to the diagnosis of multiple myeloma with crystal-storing histiocytosis, crystalline podocytopathy, and light chain proximal tubulopathy. Patient concerns: A 60-year-old male patient presented with progressive bilateral decreased vision for 2 years. Diagnosis: Ophthalmic explorations showed bilateral macular and papillary edema, and multiple crystalline deposits in the anterior stromal cornea and in the retina. Laboratory tests showed nephrotic syndrome and renal dysfunction. Further work-up revealed IgG kappa multiple myeloma, with biopsy-proven combined crystalline podocytopathy and tubulopathy. Interventions: The patient received chemotherapy (bortezomib, cyclophosphamide, and dexamethasone for 3 cycles, then bortezomib, lenalidomide, and dexamethasone). Outcomes: Despite partial hematologic response and improvement of the papilledema and macular edema, the patient developed dialysis-dependent end-stage renal failure. Lessons: This report, highlighting the protean presentation of paraprotein-mediated injuries, provides additional information on the ocular anomalies not previously described that may be associated with crystal-storing histiocytosis.