Crystalloid cytoplasmic inclusions in bone marrow plasma cells of a patient with Fanconi syndrome. A 70-year-old woman with indolent myeloma (IgGκ) developed mild renal failure. Bone marrow examination showed 17% plasmacytosis. The light microscopic (A) (Wright stain; original magnification, × 1000) and electron microscopic (B) (original magnification, × 13 680) photographs of marrow plasma cells displayed crescent-shaped cytoplasmic inclusions. The patient had low levels of serum bicarbonate and uric acid and elevated urine lysozyme (see Phillips et al⁷⁰ ).