[Polycythemia associated chronic haemolysis]

The association of erythrocytosis, splenomegaly, and iron overload represents a complex diagnostic situation that may reveal hereditary stomatocytosis related to a PIEZO1 mutation.

We report the case of a 76-year-old patient presenting with erythrocytosis, iron overload, and splenomegaly. The initial etiological workup was unremarkable. The identification of chronic hemolysis, associated with a decreased oxygen partial pressure at which 50% of haemoglobin is saturated with oxygen (venous P50) and abnormalities in erythrocyte deformability, guided further molecular investigations. Next-generation sequencing (NGS) identified a heterozygous pathogenic PIEZO1 mutation, confirming the diagnosis of stomatocytosis.

This case highlights a misleading presentation of chronic hemolysis masked by polycythemia. Venous P50 appears to be a key discriminating marker. An integrated approach combining biological and molecular analyses is essential to avoid diagnostic delay.