🚩Psammomatous calcification in ascitic fluid (Pap) Lamellated concentric rings Classically associated w/ serous carcinoma (ovary/Gyn tract) Look for an epithelial component (supporting malignancy; peritoneal involvement) Also consider RCC, PTC, other papillary #PathTwitter

Spherule-thyroid FNA (DQ) Round cohesive cluster of follicular cells forming 3D sphere ±colloid Note bland nuclei, smooth contours Supportive of benign Dx (contextual) Contrast to microfollicles (<15 cells, scant colloid, tight sphere), suggesting follicular lesion #PathTwitter

Bubble-wrapped🫧 tumor cells of papillary RCC in a FNA kidney (DQ, CB) Loosely cohesive papillary clusters of cells w/ round uniform nuclei, closely associated w/ foamy macrophages ±hemosiderin ±psammoma bodies Workup: CK7, AMACR, CD10 MET mutations (hereditary form) #PathTwitter

Phantom yeasts: treated Cryptococcus in CSF (Pap) Note round empty spaces/halos (only capsule may remain post-Rx, major virulence factor), distorted yeast forms (poorly stained) Minimal inflammation (immune compromise CD4 <100) Mucicarmine, India ink (negative stain) #PathTwitter

A ser(i)ous identity crisis: Metastatic breast carcinoma in pleural fluid Malignant epithelial cells distinct from mesos (look for clusters, loss of polarity, nuclear pleomorphism ±nucleoli) Intracytoplasmic vacuoles or mucin Origin workup: GCDFP-15, mammaglobin, ER #PathTwitter

Submucosal syncytium: Granular cell tumor of esophagus 🔴Pseudoepitheliomatous hyperplasia of overlying mucosa (🚫SCC) Granular eosinophilic cytoplasm (lysosomes) Indistinct cell borders, ±interspersed blood vessels (🚫vascular lesions) Schwann cell origin (S100+) #PathTwitter

Ironclad: hepatic hemochromatosis Coarse golden-brown iron granules (initially Zone 1 hepatocytes if primary/HH) ±hepatocyte damage. Periportal fibrosis (bridging) > micronodular cirrhosis (seen on low power) Iron should usually be confirmed w/ Prussian blue stain. #PathTwitter

The multinucleated drama of Herpesvirus infection on Pap smear (ThinPrep). Classic findings/cytopathic effects-the 3Ms: *M*ultinucleation (≥3) nuclear *M*olding ground-glass chromatin *M*argination -Can be seen even in asymptomatic pts -Can mimic 🔴HSIL #PathTwitter #CytoPath

Blood smear showing stomatocytes (coffee-bean/slit-like pallor) Found in Rh null disease (absolute ❌D, C, E antigens), mutated RHAG (Rh Associated Glycoprotein) gene (transporter for the antigens to the RBC membrane) >Chronic hemolytic anemia #KnowToPass #PathBoards #PathTwitter

🔴Goblet cell adenocarcinoma of distal appendix Note expansion of appendix wall, goblet cell morphology (cell groups dissect through muscularis propria) Grade according to tubular pattern (G1 >75%; G2 50-75%; G3 <50%) 🧬WNT pathway, ARID1/2 #KnowToPass #PathBoards #PathTwitter

ABO typing Checking pt's RBC antigens & plasma Abs, via agglutination ‣Forward typing: use pt RBCs ‣Reverse typing: use pt plasma Concordance has to be demonstrated & a discrepancy must be investigated before the ABO type can be interpreted #KnowToPass #PathBoards #PathTwitter

Here is an intraductal papilloma involved by collagenous spherulosis (! not ADH/DCIS) #PathBoards #PathPitfall

Breast-collagenous spherulosis 🟢Intraductal deposits of acellular basement membrane material (PAS+). Common w/ sclerosis, papilloma, UDH 📌🛑Myoeps are often compressed (! not DCIS/adenoid cystic carcinoma) #KnowToPass OR as @smlungpathguy says #KnowOrFail 💀😬 #PathTwitter