Charlie Herndon

#MedStudents curious what pathologists actually do? Join @Pathologists @KMirza and @RoseannIWu for this webinar following a real case from biopsy to diagnosis—you will see how pathology shapes clinical decisions and patient care. 🗓️ Sept 22, 2026 ⏰ 5 PM PT 🔗 cap-org.zoom.us/webinar/regist… #Pathology #MedEd #MedTwitter #PathMatch27 #PathTwitter

✅ Tubulocystic Renal Cell Carcinoma 🎯🧬 • Exclusive tubulocystic growth of small to intermediate-sized tubules and cysts lined by a single layer of hobnail cells • Eosinophilic cells display enlarged, irregular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm • Characterized genetically by a consistent gain of chromosome 17 and losses of chromosomes 9 and Y • Usually follows an indolent clinical course with an excellent prognosis, though rare metastases are documented

❌ Clear Cell Papillary Renal Cell Tumor: • Tubulopapillary or cystic growth of cuboidal clear cells with linearly aligned, luminal-oriented nuclei • Stains strongly and diffusely for CK7 and exhibits a unique basolateral, "cup-like" CAIX expression pattern • Lacks the prominent eosinophilic hobnail cells and the characteristic genetic gains/losses of tubulocystic RCC

#PathQuiz 🔬🧬 A) Multilocular Cystic Renal Neoplasm of Low Malignant Potential B) Acquired Cystic Disease-Associated RCC C) Clear Cell Papillary Renal Cell Tumor D) Tubulocystic Renal Cell Carcinoma #Pathology #GUPath

✅ Clear cell renal cell carcinoma 🎯💎 • Characteristic clusters of cells with broad, foamy, or clear vacuolated cytoplasm • Nuclei show coarsely structured chromatin and prominent, distinct macronucleoli • Immunoprofile shows nuclear positivity for PAX8 and membranous positivity for CD10 and RCCma • History of renal masses and hemorrhagic background are important clinical and morphologic clues

Which ancillary test result is characteristic? A) PAX8 (+) and CD10 (+) B) Melan A (+) and Inhibin (+) C) Glypican-3 (+) and HepPar-1 (+) D) GATA3 (+) and p63 (+)

#PathQuiz 🔬 Mass in right abdomen. A) Adrenocortical adenoma B) Hepatocellular carcinoma C) Urothelial carcinoma D) Clear cell renal cell carcinoma #Pathology #Cytopathology

✅ Low-grade Oncocytic Tumor 🎯🧬 • Solid growth of oncocytic cells with uniform, bland nuclei lacking prominent nucleoli or nuclear wrinkles • Distinctive IHC profile: strong and diffuse CK7 positivity, while KIT is often negative or only focal • Driven by mutations in genes of the mTOR pathway, particularly TSC1, TSC2, or MTOR • Recognizing this newly defined entity is crucial, as it behaves in an indolent manner and overlaps with oncocytoma/ChRCC

❌ SDH-Deficient Renal Cell Carcinoma: • Bland cells with pale, bubbly eosinophilic cytoplasm and flocculent cytoplasmic inclusions • Characteristically shows complete loss of SDHB immunohistochemical expression • Associated with germline SDH mutations and lacks diffuse CK7 staining

#PathQuiz 🔬🧬 A) Renal Oncocytoma B) Chromophobe Renal Cell Carcinoma C) SDH-Deficient Renal Cell Carcinoma D) Low-grade Oncocytic Tumor #Pathology #GUPath