Question: A 6-year-old child has periorbital edema and frothy urine. Labs show heavy proteinuria and hypoalbuminemia. Which renal lesion is most likely? A) Subepithelial humps on EM B) Podocyte foot process effacement on EM C) Tram-track appearance on light microscopy D) Focal segmental sclerosis with hyalinosis Correct answer: B Explanation: This presentation is classic for minimal change disease, where light microscopy is often normal and EM shows diffuse effacement of podocyte foot processes. The key pathology point is loss of the slit diaphragm barrier leading to selective albuminuria. Reference: podocyte injury and nephrotic syndrome patterns.

Question: A peripheral lung mass in a non-smoker shows gland formation and mucin production. Which immunostain profile best supports the diagnosis? A) TTF-1 positive, Napsin A positive B) p40 positive, CK5/6 positive C) Synaptophysin positive, chromogranin positive D) CD20 positive, PAX5 positive Correct answer: A Explanation: Lung adenocarcinoma commonly shows TTF-1 and Napsin A positivity, reflecting pneumocyte lineage and supporting a primary lung origin. Squamous cell carcinoma is typically p40 and CK5/6 positive, while neuroendocrine tumors express synaptophysin and chromogranin. Reference: common lung tumor immunohistochemistry patterns.

Question: A colonic biopsy shows elongated, hyperchromatic nuclei crowded at the base of glands (pseudostratification) and reduced goblet cells. Which diagnosis best fits? A) Hyperplastic polyp B) Tubular adenoma C) Ulcerative colitis, quiescent phase D) Ischemic colitis Correct answer: B Explanation: Tubular adenomas show dysplastic epithelium with nuclear hyperchromasia, elongation, and pseudostratification, often with reduced mucin and goblet cells. Hyperplastic polyps keep normal maturation and serrated architecture without true dysplasia. Reference: adenoma dysplasia criteria in colorectal pathology.