FatimaShamsPath posts effusion IHC puzzle

- Pathologist Fatima Shamsuddin shared pleural effusion cytology from an 83‑year‑old man in which CK20 and calretinin immunostains were both negative on the sample. - The simultaneous absence of CK20 (epithelial marker) and calretinin (mesothelial marker) complicated distinguishing metastatic carcinoma from mesothelial processes on limited cytology. - The post illustrated why combining cytomorphology, panel selection, and clinical history is crucial when IHC panels are inconclusive. (x.com)