stomocytic

Stomocytic, in hematology, refers to red blood cells that display stomatocytes—cells with a cup-like shape and a mouth-shaped central pallor. On a peripheral blood smear, stomocytes show a slit-like central pallor that resembles a mouth, giving the cell a concave, elongated appearance. The term can describe the cells themselves (stomatocytes) or the pattern seen on a smear (stomatocytosis). Stomatocytes arise from membrane abnormalities that alter the balance of osmotic and ionic forces across the red cell membrane, affecting cell volume and shape.

Hereditary stomatocytosis is the most prominent form, a group of inherited red blood cell membrane disorders. The two main hereditary forms are dehydrated hereditary stomatocytosis (DHS) and overhydrated hereditary stomatocytosis (OHSt). DHS is typically linked to mutations in PIEZO1 and results in reduced cellular hydration, while OHSt is associated with RHAG gene mutations and related pathways causing increased permeability to cations and cell swelling. Both conditions produce stomocytes on smear and can cause hemolytic anemia of varying severity. Acquired forms of stomatocytosis have been described in certain liver diseases, alcohol exposure, and drug toxicities, though this is less common than hereditary forms.

Diagnosis is based on a peripheral smear showing stomocytes, supported by clinical history and genetic testing for PIEZO1, RHAG, and related genes. Management focuses on monitoring and treating anemia and hemolysis, with supportive care as needed; definitive treatment depends on the underlying cause. Splenectomy is not routinely indicated for stomatocytosis.

See also: erythrocyte morphology, poikilocytosis, hereditary spherocytosis, erythrocyte membrane disorders.