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Langerhans Cell Histiocytosis (LCH), historically referred to as Histiocytosis X, represents a spectrum of clonal dendritic cell disorders ranging from the typically localized and indolent unifocal eosinophilic granuloma to the more aggressive multifocal form and the fulminant disseminated variant previously known as Letterer–Siwe disease, which carries a high risk of morbidity and mortality. This heterogeneous group of conditions is characterized […]

Gaucher’s disease is a rare inherited lysosomal storage disorder caused by deficient activity of the enzyme glucocerebrosidase. This autosomal recessive condition results from pathogenic variants in the GBA gene, leading to the accumulation of glucocerebroside within macrophages. These lipid-laden “Gaucher cells” progressively infiltrate the liver, spleen, bone marrow, and—in some subtypes—the central nervous system, producing a wide spectrum of clinical […]

Sea Blue Histiocytes are enlarged, lipid-laden macrophages found in the bone marrow that characteristically exhibit a deep sea-blue cytoplasmic staining on Romanowsky preparations. These distinctive cells arise when histiocytes accumulate phospholipids or other lipids that resist normal degradation pathways, giving them their granular blue appearance under light microscopy. Although Sea Blue Histiocyte Syndrome is a rare autosomal dominant condition associated […]

Chediak-Higashi Syndrome (CHS) is a very rare autosomal recessive primary immunodeficiency disorder characterized by a complex mutation in a lysosomal trafficking regulator protein. This mutation severely impairs the immune system’s function (phagocytosis and bacterial lysis), leading to devastating consequences for the patient, including recurrent bacterial infections (especially respiratory), partial albinism, an increased bleeding tendency, and often progressive neurological disease. While […]

Chronic Granulomatous Disease (CGD) is a rare inherited primary immunodeficiency in which phagocytes fail to generate reactive oxygen species (ROS) due to defects in the NADPH oxidase enzyme complex. As a result, affected individuals are highly susceptible to recurrent, severe bacterial and fungal infections and may develop granulomatous inflammation in various organs. The study of CGD has been pivotal in […]

Lupus Erythematosus (LE) cells are characteristic neutrophils that have phagocytosed the denatured nuclear material of damaged lymphocytes, typically coated with autoantibodies against nucleoproteins. First identified by Dr. Robert H. Heitzman in 1948, LE cells once served as a key diagnostic marker for systemic lupus erythematosus (SLE), reflecting the autoimmune pathophysiology of the disease. Although largely replaced today by more sensitive […]

Pelger-Huët Anomaly (PHA) is a rare, typically benign hereditary disorder of neutrophil nuclear segmentation, characterised by bilobed or peanut-shaped nuclei instead of the normal multilobed appearance. This distinctive morphology affects neutrophils and other granulocytes and is often discovered incidentally on a peripheral blood smear. Although most individuals with true (inherited) PHA remain asymptomatic with normal immune function, similar morphological changes—termed […]