Cytomorphology is largely conserved across molecular subtypes of SCLC, 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.
Mizoguchi et al. (Fri,) studied this question.