<unk><unk><unk>  cell in spleen<unk> s are a subgroup of lipid storage disorders called sphingolipidoses in which harmful quantities of fatty substances, or lipids, accumulate in the spleen, liver, lungs, bone marrow, and brain. In the classic infantile type-A variant, a missense mutation causes complete deficiency of sphingomyelinase. Sphingomyelin is a component of cell membrane including the organellar membrane, so the enzyme deficiency blocks degradation of lipid, resulting in the accumulation of sphingomyelin within lysosomes in the macrophage-monocyte phagocyte lineage. Affected cells become enlarged, sometimes up to 90 μm in diameter, secondary to the distention of lysosomes with sphingomyelin and cholesterol. Histology shows lipid-laden macrophages in the marrow and "sea-blue histiocytes" on pathology. Numerous small vacuoles of relatively uniform size are created, giving the cytoplasm a foamy appearance.
Niemann–Pick disease
Wilson's disease
Wilson–Mikity syndrome
Haemochromatosis type 3
Mowat–Wilson syndrome
Hemochromatosis type 4
Gaucher's disease
Maroteaux–Lamy syndrome