[Niemann-Pick disease with two missense mutations in SMPD1 gene: a case report and literature review].

This report describes a case of Niemann-Pick disease caused by double missense mutations in the SMPD1 gene and investigates the morphological relationship between Niemann-Pick cells and sea-blue histiocytes. The patient's bone marrow smear showed typical Niemann-Pick cells, containing small to moderate sea-blue granules, as well as sea-blue histiocytes. Next-generation sequencing revealed heterozygous SMPD1 mutations c.1361C>A (p. Ala454Asp) and c.1666C>T (p. His556Tyr). While these mutations were previously reported in the literature, their clinical significance remains unclear. Since missense mutations in SMPD1 are pathogenic and can cause Niemann-Pick disease, it is hypothesized that a morphological link exists between Niemann-Pick cells and sea-blue histiocytes. Combining bone marrow morphology with genetic testing can improve the diagnostic accuracy for this disease and other related lipid storage disorders.