Clin Chem Lab Med. 2026 Jul 7. doi: 10.1515/cclm-2026-0957. Online ahead of print.
ABSTRACT
OBJECTIVES: Red blood cell (RBC) morphology in peripheral blood smears (PBS) remains essential for the differential diagnosis of anemia and other hematologic disorders. As yet unclassified poikilocytes, fish-shaped RBCs and pincer (mushroom-shaped) cells are rarely observed but have been described as “bizarre erythrocytes” and linked to hereditary spherocytosis. This study aimed to investigate their relevance across a spectrum of hematologic diseases and provide a basis for future morphological standardization.
METHODS: Peripheral blood smears from 251 specimens were systematically reviewed, including cases of iron deficiency anemia (IDA), β-thalassemia minor (BTM), sickle cell disease (SCD), microangiopathic hemolytic anemia (MAHA), autoimmune hemolytic anemia (AIHA), hereditary spherocytosis (HS), hereditary elliptocytosis (HE), vitamin B12/folate deficiency, myelodysplastic neoplasms (MDS), primary myelofibrosis (PMF), malaria, liver disease (LD), and healthy controls. Abnormal RBC morphologies were quantified as cells per 20 high-power fields at 1,000 × magnification. Group comparisons used the Mann-Whitney U test and correlations were assessed by Spearman’s rank correlation.
RESULTS: Numbers of fish-shaped and pincer cells were significantly increased in IDA, BTM, MDS, HE, PMF, and vitamin B12/folate deficiency with a strong positive intercorrelation (p<0.01) in most of these diseases. Pincer cells were also elevated in HS and hemoglobin levels were negatively correlated with both fish and pincer cells across all disorders studied (p<0.0001).
CONCLUSIONS: Fish-shaped RBCs and pincer cells represent abnormal erythrocyte morphologies associated with a range of hematologic disorders and correlate with severity of anemia. Their strong intercorrelation suggests a shared pathophysiologic mechanism or may reflect different stages of a common morphological process.
PMID:42406051 | DOI:10.1515/cclm-2026-0957