JCandidoXavier shows collision tumor atypia

- Pathologist JCandidoXavier posted a collision tumor case demonstrating marked atypia and overlapping morphologies that confused initial cytologic classification. - The thread stressed how collision tumors can show divergent differentiation in small samples, producing extreme pleomorphism and mixed immunoprofiles on tiny cores or smears. - Contributors recommended broad panels and low threshold for excisional biopsy when cytology shows incompatible marker patterns. (x.com)