Crystal-storing histiocytes and plasma cells, crystalline corneal deposits and atypical MRI lesions in multiple myeloma

[摘要] A 46-year-old male presented to his General Practitioner (GP)feeling generally unwell with bony aches and blurriness of vision.Routine blood tests performed by the GP showed acute kidneyinjury with creatinine of 121 µmol/L. Subsequent blood tests performed at the renal clinic showed a mild anemia of 125 g/L andan IgG kappa paraprotein of 17.2 g/L. The rest of his full bloodcount, renal and calcium profiles were within the normal ranges. Abone marrow examination showed a 35% population of neoplasticplasma cells, which were cytoplasmic kappa light chain restrictedand positive for CD38, CD138, CD56, and CD200 confirming thediagnosis of myeloma. The bone marrow morphology was remarkable for crystal-storing histiocytes and plasma cells (Figure 1A,B atobjective ×100). An ophthalmology examination revealed crystalline corneal deposits and anterior chamber inflammation, with completecorneal stroma infiltration bilaterally making corneae appear hazyon slit lamp examination (Figure 2). Whole spine specialized magnetic resonance imaging (MRI) sequences showed unusual low signalosseous deposits (Figure 3) without hypersensitivity, which wereatypical for lytic lesions, but suspicious for paraprotein crystallinedeposition.