Pathologies of Renal and Systemic Intracellular Paraprotein Storage: Crystalopathies and Beyond

Bone marrow imprints of crystal‐storing histiocytosis

“…Ultrastructural examination usually shows needle‐shaped, rectangular, polygonal or rhomboid electron‐dense crystals of variable size, which may show striations indicating periodicity, and are bound by a limiting single unit membrane, consistent with their intralysosomal deposition. Deposition of such crystals in renal tubular cells, the crystalline variant of light chain proximal tubulopathy, causing partial or complete Fanconi syndrome, has been described in association with CSH . Similar, albeit smaller and less abundant crystals may form within the endoplasmic reticulum of the neoplastic lymphocytes (chronic lymphocytic leukemia) or neoplastic plasma cells themselves, and may be referred to as Auer‐rod‐like inclusions …”