Figure 1.

Plasma cell myeloma with intracytoplasmic and extracellular rhomboid crystalline inclusions. (a and b) Bone marrow aspirate stained with Wright-Giemsa. Note abundant rhomboid crystals present in the extracellular space (a; arrows) and intracytoplasmic in plasma cells (b; arrow-heads). (c) H&E stain of bone marrow biopsy section showing prominent rhomboid crystals (arrow). (d) Immunohistochemistry for lambda-chain highlights monotypic plasma cells with positive stain of the extracellular crystals (arrow). Bar 200 μm (a), 20 μm (b), and 50 μm (c and d).