Cytologic Features Across Molecular Subtypes of Small Cell Lung Carcinoma: Classical Uniformity With Exceptions in POU2F3-Positive Cases.

Cytomorphology is largely conserved across molecular subtypes of small cell lung carcinoma, but a minority of POU2F3-positive tumours may display non-classical features.

Recognition of this variant is important to avoid misclassification, particularly when only limited cytology material is available.

These findings suggest that lineage-defining programs may occasionally imprint the cytologic phenotype and highlight the value of considering subtype-oriented ancillary testing in challenging cases.