Crystal-storing histiocytosis (CSH) is a rare event observed in association with lymphoproliferative diseases, and mainly occurrs in plasma cell dyscrasias. It is presumed to be an intra-lysosomal accumulation of the secreted paraproteins. Crystal formation can be seen inside histiocyte-like cells with phagocytosed crystalline inclusions in the bone marrow and extramedullary sites. CSH is a rare morphological entity with poor prognostic implications and may be confused with Gaucher or pseudo-Gaucher cells. Herein we report a case of non-secretory myeloma associated with CSH showing a poor clinical course. A 79-yr-old male presenting with dizziness was evaluated in hematology department for anemia. Laboratory tests revealed Hb of 4.9 g/dL and beta2-microglobulin of 21,000 ng/mL (reference range, 0-370). Presence of monoclonal protein was not detected on protein electrophoresis and immunofixation in serum and urine. However, serum free light chain assay showed an increased kappa-light chain level of 126 mg/L (reference range, 3.3-19.4) resulting in an increased kappa/lambda ratio. The bone marrow touch print showed numerous plasma cells and crystal-laden histiocytes and immunohistochemical stainings on bone marrow biopsy revealed positivity for CD38, CD56 and kappa in the plasma cells and CD68 and kappa in crystal-laden histiocytes.
Aged ; Antigens, CD/metabolism ; Antigens, CD38/metabolism ; Antigens, Differentiation, Myelomonocytic/metabolism ; Bone Marrow Cells/pathology ; Histiocytosis/complications/*diagnosis/radiography ; Humans ; Immunoglobulin kappa-Chains/analysis ; Male ; Multiple Myeloma/complications/*diagnosis/radiography ; Tomography, X-Ray Computed

We report a case of multiple myeloma that presented as a fluctuating sixth cranial nerve palsy in the absence of widespread signs of systemic disease. A 63-year-old woman presented with horizontal diplopia of two weeks duration that subjectively changed over time. Ocular examination showed a fluctuating sixth nerve palsy. A computed tomography (CT) scan of the brain showed multiple, enhancing, soft tissue, mass-like lesions involving the left cavernous sinus and the apex of both petrous bones. Based on bone marrow biopsy and hematologic findings, she was diagnosed with multiple myeloma. Multiple myeloma may be included in the differential diagnosis of a fluctuating sixth nerve palsy, and although ophthalmic signs are rare and generally occur late in the course of multiple myeloma, they can still be its first signs.
Abducens Nerve Diseases/diagnosis/*etiology ; Brain/pathology/radiography ; Diagnosis, Differential ; Diplopia/etiology ; Esotropia/etiology/physiopathology ; Female ; Humans ; Magnetic Resonance Imaging ; Middle Aged ; Multiple Myeloma/*complications/diagnosis ; Tomography, X-Ray Computed