title: Sea-blue histiocytosis secondary to Niemann-Pick disease type B: a case report.
abstract: Sea-blue histiocytosis is a morphological finding that can be associated both with acquired conditions of increased cellular turnover and inborn errors of lipid metabolism. We report a rare case of sea-blue histiocytosis associated with a mild phenotype of Niemann-Pick disease (NPD) type B in a 44-year-old man who presented with splenomegaly and mild thrombocytopenia. Diagnosis was guided by the morphological finding in bone marrow smears of foamy and sea-blue histiocytes and confirmed by the measurement of acid lysosomal sphingomyelinase activity below normal values. NPD type B is a rare inborn error of metabolism, with a benign course and prognosis, while types A and C are always associated with severe neurological involvement. In our patient diagnosis was confirmed by the specific enzyme assay of leukocytes (deficiency in sphingomyelinase activity). This is a simple and noninvasive method that is useful whenever clinical and morphological finding are relevant, and a primary hematological disorder has been ruled out.
authors.affiliation: Department of Bone Marrow Transplantation, University Hospital, Udine, Italy. Ematologia@drmm.uniud.it
authors.forename: A
authors.initials: A
authors.lastname: Candoni
authors.forename: S
authors.initials: S
authors.lastname: Grimaz
authors.forename: P
authors.initials: P
authors.lastname: Doretto
authors.forename: R
authors.initials: R
authors.lastname: Fanin
authors.forename: F
authors.initials: F
authors.lastname: Falcomer
authors.forename: B
authors.initials: B
authors.lastname: Bembi
mesh_terms: D000328:Adult; D006801:Humans; D007962:Leukocytes / Q000201:enzymology; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D009542:Niemann-Pick Diseases / Q000150:complications* / Q000175:diagnosis; D012618:Sea-Blue Histiocyte Syndrome / Q000175:diagnosis / Q000209:etiology*; D013108:Sphingomyelin Phosphodiesterase / Q000097:blood; D013163:Splenomegaly; D013921:Thrombocytopenia
chemical_list: D013108:Sphingomyelin Phosphodiesterase