Practice 5 structured short- and long-answer medical questions on Weekly Pathology Exam - September 11, 2026 (Sections B & C). Review model answers for exam...
Answer: Key histological features of BPH nodules include: 1. **Stromal hyperplasia:** Increased smooth muscle and fibroblastic stroma. 2. **Epithelial hyperplasia:** Enlargement and crowding of prostatic acini lined by tall, pseudostratified columnar or cuboidal epithelium. 3. **Cribriform pattern:** Glandular structures may appear fused or have a sieve-like appearance due to back-to-back acini or intraluminal papillary projections. 4. **Absence of atypia or malignancy:** The epithelial cells typically show mild pleomorphism but lack significant nuclear atypia, prominent nucleoli, or mitotic activity characteristic of malignancy.
Answer: The main immunohistochemical markers used to distinguish between HCC and CCC include: **For Hepatocellular Carcinoma (HCC):** * **Hepatocyte-specific antigen (HepPar-1):** Typically positive in HCC, showing cytoplasmic staining. * **Arginase-1:** Similar distribution to HepPar-1, strongly indicative of hepatocellular origin. * **Alpha-fetoprotein (AFP):** Can be positive, though not always, and is more commonly seen in poorly differentiated HCC. **For Cholangiocarcinoma (CCC):** * **Cytokeratin 7 (CK7):** Typically positive in CCC, highlighting bile duct epithelium. * **Cytokeratin 19 (CK19):** Also typically positive in CCC, particularly in well-differentiated forms. * **Carcin Embryonic Antigen (CEA):** Can be positive, often showing a luminal or apical pattern. **Markers that can be helpful in differentiation but less specific:** * **CD10:** Can be positive in HCC, but negative in CCC. * **Glypican-3:** Strongly positive in HCC, especially well-differentiated types, and negative in CCC. * **MOC-31:** Usually positive in epithelial cells of biliary origin (CCC) and negative in hepatocytes (HCC).
Answer: Gastric ulcers are typically caused by an imbalance between aggressive factors and protective mechanisms in the gastric mucosa. The primary aggressive factor is **gastric acid and pepsin**, which can digest the gastric lining. Protective mechanisms include the **mucosal barrier** (mucus and bicarbonate), **mucosal blood flow**, and **epithelial cell regeneration**. The most common cause of this imbalance is infection with *Helicobacter pylori*, which damages the mucosal barrier and promotes inflammation. Other significant causes include the use of **non-steroidal anti-inflammatory drugs (NSAIDs)**, which inhibit prostaglandin synthesis (essential for mucus and bicarbonate production and mucosal blood flow), and **Zollinger-Ellison syndrome**, which causes excessive gastrin production and thus hyperacidity. In summary, the pathogenesis involves: 1. **Disruption of the mucosal defense mechanisms** (e.g., by *H. pylori* or NSAIDs). 2. **Increased exposure of the mucosa to gastric acid and pepsin**. 3. **Direct injury to the epithelial cells**. 4. **Inflammation and impaired healing**.
Answer: The characteristic histological findings in the small intestinal biopsy of a patient with celiac disease, typically in the duodenum or proximal jejunum, include: 1. **Villous atrophy:** Significant flattening or absence of the normal finger-like villi. 2. **Crypt hyperplasia:** Elongation and increased cellularity of the intestinal crypts, which are located at the base of the villi. 3. **Increased intraepithelial lymphocytes (IELs):** A marked increase in lymphocytes infiltrating the epithelial layer lining the villi and crypts. These are predominantly T cells. 4. **Epithelial cell changes:** May show basal cell vacuolation and flattening of enterocytes. The severity of these changes can be graded using the Marsh classification.
Answer: **Gross Findings:** The TURP specimen will typically consist of multiple irregular fragments of prostatic tissue. These fragments can vary in size from small shavings to larger nodules. The cut surface may appear tan-white to yellowish, and in cases of significant hyperplasia, it might have a fleshy or adenomatous appearance. Hemorrhagic areas may also be present due to the resection process. Careful examination for any suspicious firm or indurated areas that might suggest malignancy is important, though these are often not readily apparent in routine TURP specimens for benign conditions. **Microscopic Findings:** Histological examination will reveal the hallmark features of **benign prostatic hyperplasia (BPH)**. This includes: 1. **Stromal Hyperplasia:** An increased proliferation of smooth muscle and fibroblastic stroma, forming nodules. This stromal component often dominates the picture. 2. **Epithelial Hyperplasia:** Enlargement and crowding of prostatic acini. These acini are typically lined by tall, pseudostratified columnar or cuboidal epithelium. The nuclei are generally regular, with mild pleomorphism, but should lack significant atypia, prominent nucleoli, or mitotic figures suggestive of malignancy. 3. **Cribriform Pattern:** Glandular structures may appear fused or have a sieve-like appearance due to back-to-back acini or intraluminal papillary projections. This is a benign feature of hyperplasia. 4. **Absence of Malignancy:** Crucially, the pathologist will carefully assess for features of prostatic adenocarcinoma. This includes identifying glands with significant nuclear atypia, irregular nuclear contours, prominent nucleoli, increased mitotic activity, perineural invasion, or a distinctly different glandular architecture (e.g., small, crowded glands with little stroma). **Clinical Significance:** * **Diagnosis of BPH:** The presence of BPH explains the patient's lower urinary tract symptoms (LUTS) such as dysuria, hesitancy, frequency, urgency, and nocturia. The enlarged prostate compresses the prostatic urethra, obstructing urine flow. * **Exclusion of Malignancy:** The most critical clinical significance of examining the TURP specimen is to rule out an incidental or clinically significant prostatic adenocarcinoma. While BPH is common, prostate cancer can coexist. Finding significant adenocarcinoma on a TURP specimen can lead to a change in management and necessitate further investigation and treatment for cancer. * **Assessment of Severity:** The degree of hyperplasia and stromal/epithelial ratio can provide some indication of the extent of prostatic enlargement and the potential for symptom relief following TURP. * **Management Guidance:** The pathological findings inform the surgeon and urologist about the nature of the prostatic enlargement and help in planning follow-up care. If malignancy is found, further staging and treatment strategies will be initiated.