Gastrointestinal Pathology — MCQs

Gastrointestinal Pathology Indian Medical PG Practice Questions and MCQs

Question 281: Lymphoepithelial change in the stomach is seen in which condition?

A. MALToma (Correct Answer)
B. Coeliac disease
C. Ipsidoma
D. IBS

Explanation: **Explanation:** **Lymphoepithelial lesions (LELs)** are the hallmark histological feature of **MALToma** (Mucosa-Associated Lymphoid Tissue lymphoma) [1]. These lesions are characterized by the invasion and destruction of gastric mucosal glands by aggregates of neoplastic B-cells (marginal zone cells). This specific interaction between the malignant lymphoid infiltrate and the overlying epithelium is diagnostic of low-grade marginal zone B-cell lymphomas [1]. **Analysis of Options:** * **A. MALToma (Correct):** Most commonly associated with *H. pylori* infection. The chronic antigenic stimulation leads to lymphoid hyperplasia, which can progress to a monoclonal B-cell population that invades the gastric pits, forming the characteristic lymphoepithelial changes [1]. * **B. Coeliac Disease:** Characterized by villous atrophy, crypt hyperplasia, and increased **intraepithelial lymphocytes (IELs)** in the small intestine, but it does not form the destructive lymphoepithelial lesions seen in MALToma. * **C. Ipsidoma (Immunoproliferative Small Intestinal Disease):** Also known as Mediterranean lymphoma, it is a variant of MALToma affecting the small intestine. While it involves lymphoid proliferation, "lymphoepithelial change" is the classic descriptor specifically emphasized for gastric MALToma in pathology exams. * **D. IBS (Irritable Bowel Syndrome):** A functional bowel disorder with no specific diagnostic histological or structural abnormalities. **High-Yield Pearls for NEET-PG:** * **Translocation:** The most common translocation in MALToma is **t(11;18)(q21;q21)** involving the *API2-MLT* genes. This translocation usually predicts resistance to *H. pylori* eradication therapy. * **Treatment:** Early-stage MALToma often regresses completely with **antibiotic treatment** for *H. pylori*. * **Markers:** MALToma cells typically express B-cell markers like **CD19, CD20, and CD79a**, but are negative for CD5, CD10, and CD23. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 356-357.

Question 282: Mucin is secreted by which organ?

A. Skin
B. Lung
C. Stomach
D. Gall bladder (Correct Answer)

Explanation: **Explanation:** The correct answer is **Gallbladder (Option D)**. The gallbladder is lined by a single layer of tall columnar epithelium. These cells possess two primary functions: the absorption of water/electrolytes (to concentrate bile) and the **secretion of mucin** [1]. Mucin serves a critical protective role, forming a chemical barrier that shields the gallbladder mucosa from the detergent-like action of concentrated bile salts. In pathological states, such as chronic cholecystitis, there is often an overproduction of mucin, which can lead to "mucocele" of the gallbladder if the cystic duct is obstructed [3]. **Analysis of Incorrect Options:** * **Skin (A):** The skin is composed of keratinized stratified squamous epithelium. Its primary secretions are sebum (sebaceous glands) and sweat (eccrine/apocrine glands), not mucin. * **Lung (B):** While the respiratory tract contains goblet cells and submucosal glands that secrete mucus, the lung parenchyma (alveoli) consists of Type I and Type II pneumocytes. Type II pneumocytes secrete **surfactant**, not mucin. * **Stomach (C):** While the stomach does secrete mucus (via foveolar cells), in the context of this specific question (often sourced from standard pathology texts like Robbins), the gallbladder is highlighted for its distinct columnar secretory activity [2]. However, if this were a "multiple correct" scenario, the stomach would be a contender; but in standard NEET-PG patterns, the gallbladder is the classic answer for this specific recall. **High-Yield Clinical Pearls for NEET-PG:** * **Luschka’s Ducts:** These are small bile ducts in the wall of the gallbladder that can be a site for stasis and infection. * **Rokitansky-Aschoff Sinuses:** Herniations of the gallbladder mucosa into the muscularis layer, characteristic of chronic cholecystitis. * **Stain for Mucin:** PAS (Periodic Acid-Schiff) and Mucicarmine are used to identify mucin-secreting cells or adenocarcinomas. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 402-403. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 350-351. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 884-886.

Question 283: The presence of PAS-positive macrophages in the small intestine is a hallmark of which of the following conditions?

A. Whipple's disease (Correct Answer)
B. Crohn's disease
C. Celiac disease
D. Tropical sprue

Explanation: ### Explanation **Correct Answer: A. Whipple's disease** **Mechanism:** Whipple’s disease is a systemic infectious process caused by the gram-positive actinomycete **_Tropheryma whipplei_**. The hallmark histological finding is the infiltration of the small intestinal lamina propria by **bulky, foamy macrophages** [1]. These macrophages contain "sickle-shaped" intracellular organisms that are **PAS (Periodic Acid-Schiff) positive** and **diastase-resistant**. This staining occurs because the cell walls of the bacteria contain glycoproteins that react with the PAS stain. These engorged macrophages obstruct lymphatic drainage, leading to malabsorption and steatorrhea [1]. **Why the other options are incorrect:** * **Crohn's disease:** Characterized by transmural inflammation and **non-caseating granulomas** [2]. While macrophages are present, they do not show the characteristic PAS-positive inclusions seen in Whipple’s. These granulomas typically consist of epithelioid macrophages and giant cells [2]. * **Celiac disease:** The classic findings are **villous atrophy**, crypt hyperplasia, and increased intraepithelial lymphocytes (IELs). It is an immune-mediated reaction to gluten, not a bacterial infiltration. * **Tropical sprue:** Similar to Celiac disease, it shows villous atrophy and inflammation, but it typically involves the entire small intestine and lacks specific PAS-positive macrophage infiltration. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Tetrad:** Malabsorption (weight loss/diarrhea), Lymphadenopathy, Hyperpigmentation, and Polyarthritis [1]. * **Mnemonic (The 4 Ms):** **M**alabsorption, **M**esenteric lymphadenopathy, **M**acrophages (PAS+), and **M**any joints (Arthritis). * **Electron Microscopy:** Shows characteristic "bacillary organisms" (the most specific test). * **Treatment:** Long-term antibiotics (usually Ceftriaxone followed by Trimethoprim-sulfamethoxazole). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 365-367.

Question 284: What is true about Carcinoid tumors?

A. Always benign
B. Kulchitsky cell tumor (Correct Answer)
C. Present with paroxysmal hypertension
D. Punch biopsy is diagnostic

Explanation: **Explanation:** **Carcinoid tumors** are well-differentiated neuroendocrine tumors [1] that arise from the **Kulchitsky cells** (enterochromaffin cells) located in the crypts of Lieberkühn throughout the gastrointestinal tract. These cells are part of the APUD (Amine Precursor Uptake and Decarboxylation) system, making **Option B** the correct statement. **Analysis of Options:** * **Option A (Always benign):** This is incorrect. While some carcinoids are indolent, all have malignant potential [1]. The risk of metastasis depends on the site of origin (e.g., midgut tumors are more aggressive) and the size of the tumor (>2 cm increases risk) [2]. * **Option C (Paroxysmal hypertension):** This is incorrect. Carcinoid syndrome typically presents with **paroxysmal flushing, diarrhea, and wheezing**. Hypertension is not a classic feature; in fact, vasomotor collapse or hypotension can occur during a "carcinoid crisis." Paroxysmal hypertension is characteristic of Pheochromocytoma. * **Option D (Punch biopsy is diagnostic):** This is incorrect. Carcinoid tumors are often **submucosal** [4]. A superficial punch biopsy may only show normal overlying mucosa, leading to a false negative. Deep endoscopic biopsies or EUS-guided FNA are preferred. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Appendix (historically), but recent data suggests the Small Intestine/Rectum are increasingly common [1]. * **Carcinoid Syndrome:** Occurs only when the tumor metastasizes to the **liver** (bypassing first-pass metabolism) [4] or arises from extra-portal sites (e.g., Bronchial carcinoid) [3]. * **Diagnosis:** 24-hour urinary **5-HIAA** (metabolite of Serotonin). * **Histology:** Classic "salt and pepper" chromatin; cells arranged in nests or trabeculae [4]. * **Markers:** Chromogranin A (most sensitive) and Synaptophysin [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 780-781. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 375-376. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 727. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 781-782.

Question 285: Angiodysplasia is typically seen in which location?

A. Stomach of an adult
B. Jejunum of a child
C. Left side of the colon
D. Right side of the colon (Correct Answer)

Explanation: **Explanation:** **Angiodysplasia** is a common cause of lower gastrointestinal bleeding in the elderly [1]. It is characterized by malformed, dilated, and tortuous submucosal and mucosal blood vessels [1]. **Why the Right Side of the Colon is Correct:** Angiodysplasia occurs most frequently (up to 80% of cases) in the **cecum and ascending colon (Right side)** [1]. This predilection is explained by **Laplace’s Law**, which states that wall tension is proportional to the radius of the vessel/organ. Since the cecum has the widest diameter in the colon, it experiences the highest wall tension [1]. This chronic intermittent tension leads to the compression of submucosal veins, resulting in focal dilation and the formation of ectatic vascular channels. **Analysis of Incorrect Options:** * **Stomach of an adult:** While vascular malformations like GAVE (Gastric Antral Vascular Ectasia or "Watermelon Stomach") occur here, classic angiodysplasia is primarily a colonic pathology. * **Jejunum of a child:** Angiodysplasia is a degenerative disease of aging (typically >60 years). Small bowel involvement is rare, and it is not a pediatric condition [1]. * **Left side of the colon:** Although it can occur here, the lower wall tension compared to the right side makes it a much less common site. **High-Yield Clinical Pearls for NEET-PG:** * **Presentation:** Presents as painless, episodic hematochezia or occult blood loss in patients over 60 [1]. * **Association:** Frequently associated with **Aortic Stenosis** (Heyde’s Syndrome) and Chronic Kidney Disease. * **Heyde’s Syndrome:** The triad of Aortic Stenosis, Angiodysplasia, and acquired von Willebrand deficiency (due to depletion of high-molecular-weight multimers across the stenotic valve). * **Diagnosis:** Colonoscopy is the gold standard, showing characteristic "cherry-red" fern-like or spider-like vascular lesions. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 787-789.

Question 286: What is the role of the thick mucous coat in the gastrointestinal tract?

A. It is protective in ulcer patients. (Correct Answer)
B. It is not protective in ulcer patients.
C. It is easily destroyed by antacids.
D. It is commonly associated with carcinomatous change.

Explanation: The gastrointestinal (GI) mucosa is protected by a sophisticated **mucosal barrier**, primarily composed of a thick layer of mucus and bicarbonate ions [1]. This barrier is the first line of defense against the aggressive factors of the stomach, such as hydrochloric acid (HCl) and pepsin [1]. ### **Explanation of Options** * **Option A (Correct):** In patients with peptic ulcer disease (PUD), the thick mucous coat acts as a physical and chemical shield [1]. It traps bicarbonate ions, creating a pH gradient that neutralizes acid before it reaches the epithelial surface. It also prevents the proteolytic enzyme **pepsin** from digesting the underlying tissue. Strengthening this barrier (e.g., via prostaglandins or sucralfate) is a key therapeutic goal in ulcer management [1]. * **Option B:** This is incorrect because the mucous coat is the primary physiological defense mechanism. Its impairment (often due to *H. pylori* or NSAIDs) is exactly what leads to ulcer formation [1]. * **Option C:** Antacids do not destroy the mucous coat; rather, they neutralize the acid within the lumen. Some agents, like sucralfate, actually bind to the mucus to enhance its protective properties. * **Option D:** While chronic inflammation (gastritis) can lead to intestinal metaplasia and eventually carcinoma, a healthy thick mucous coat is a normal physiological feature and is not a precursor to malignancy. ### **High-Yield Clinical Pearls for NEET-PG** * **The "Mucosal Barrier":** Comprises the pre-epithelial (mucus/bicarbonate), epithelial (tight junctions), and post-epithelial (rich blood flow) layers. * **Prostaglandins (PGE2):** These are vital for maintaining the mucous coat. They stimulate mucus and bicarbonate secretion and maintain mucosal blood flow. This explains why **NSAIDs** (which inhibit COX and prostaglandins) cause ulcers [1]. * **H. pylori:** This pathogen produces **proteases and lipases** that specifically degrade the mucous coat, allowing acid to damage the epithelium [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 767-774.

Question 287: Gastrointestinal stromal tumors (GIST) arise from mutations in which of the following genes?

A. c-KIT oncogene (Correct Answer)
B. c-KTT oncogene
C. c-KTT oncogene
D. c-RET oncogene

Explanation: **Gastrointestinal Stromal Tumors (GIST)** are the most common mesenchymal tumors of the abdomen. They originate from the **Interstitial Cells of Cajal (ICC)**, which serve as the electrical pacemakers of the gut. **1. Why c-KIT is correct:** Approximately 75–85% of GISTs are driven by an activating mutation in the **c-KIT oncogene** (CD117). This gene encodes a receptor tyrosine kinase. The mutation leads to constitutive activation of the kinase signaling pathway, resulting in uncontrolled cell proliferation [1]. In cases where c-KIT is not mutated, about 8% of GISTs harbor mutations in **PDGFRA** (Platelet-Derived Growth Factor Receptor Alpha) [1]. **2. Why the other options are incorrect:** * **Options B & C (c-KTT):** These are distractors. "c-KTT" is not a recognized oncogene; it is a common spelling trap used in competitive exams to test precision. * **Option D (c-RET):** The RET proto-oncogene is associated with **Multiple Endocrine Neoplasia (MEN) type 2A and 2B**, Medullary Thyroid Carcinoma, and Hirschsprung disease, but not GIST [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Stomach (60%), followed by the small intestine (30%) [1]. * **Immunohistochemistry (IHC) Marker:** **DOG1** (Discovered On GIST 1) is the most sensitive and specific marker, especially in c-KIT negative cases. **CD117** is the standard diagnostic marker. * **Morphology:** Most GISTs show a **spindle cell** pattern (70%). * **Targeted Therapy:** **Imatinib mesylate**, a tyrosine kinase inhibitor, is the first-line treatment for unresectable or metastatic GIST. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 782-783. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 292.

Question 288: Which of the following is a marker for carcinoma of the colon?

A. AFP
B. CA-125
C. CEA (Correct Answer)
D. HCG

Explanation: **Explanation:** The correct answer is **CEA (Carcinoembryonic Antigen)**. **Why CEA is the correct answer:** CEA is an oncofetal glycoprotein normally produced during fetal development in the gastrointestinal tract. In adults, its expression is very low; however, it becomes significantly elevated in adenocarcinomas, most notably **Colorectal Carcinoma (CRC)** [1]. * **Clinical Utility:** It is important to note that CEA is **not used for screening** due to low sensitivity and specificity (it can be elevated in smokers, cirrhosis, and inflammatory bowel disease). Its primary role is in **monitoring treatment response** and **detecting tumor recurrence** post-surgery [1]. A rising CEA level after resection is a strong indicator of tumor return. **Analysis of Incorrect Options:** * **A. AFP (Alpha-Fetoprotein):** An oncofetal marker primarily associated with **Hepatocellular Carcinoma (HCC)** and non-seminomatous germ cell tumors (specifically **Yolk Sac Tumors**). * **B. CA-125:** The primary biomarker used for monitoring **Ovarian Cancer** (specifically epithelial types like serous cystadenocarcinoma). * **C. HCG (Human Chorionic Gonadotropin):** A marker for pregnancy, but pathologically associated with **Choriocarcinoma** and **Hydatidiform moles**. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of CRC metastasis:** Liver (detected via elevated CEA and imaging). * **Genetic Pathway:** Most sporadic colon cancers follow the **APC-adenoma-carcinoma sequence** (APC → KRAS → TP53). * **Left vs. Right:** Left-sided cancers often present with "napkin-ring" constriction and altered bowel habits; right-sided cancers often present with iron deficiency anemia due to occult bleeding [2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 213-214. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 207-208.

Question 289: Which of the following statements are true about gastric lymphoma?

A. Non-Hodgkin's lymphoma is the commonest variety. (Correct Answer)
B. Diagnosis is made by biopsy.
C. It is chemoresistant.
D. It is essentially of B-cell type.

Explanation: **Gastric Lymphoma: Explanation** Gastric lymphoma is the most common site for extranodal lymphomas, accounting for approximately 1–5% of all gastric malignancies [1]. **Why Option A is Correct:** The vast majority of primary gastric lymphomas are **Non-Hodgkin’s Lymphomas (NHL)** [1]. Hodgkin’s disease involving the stomach is extremely rare and usually occurs as part of systemic dissemination. Within the NHL category, the two most common subtypes are **MALToma** (Mucosa-Associated Lymphoid Tissue) and **Diffuse Large B-Cell Lymphoma (DLBCL)** [1]. **Analysis of Other Options:** * **Option B:** While biopsy is essential for diagnosis, it is often challenging because gastric lymphoma frequently grows in the **submucosa**. Superficial endoscopic biopsies may yield false negatives [2]; therefore, deep "jumbo" biopsies or EUS-guided sampling are often required. * **Option C:** Gastric lymphoma is highly **chemosensitive** and radiosensitive [1]. Unlike gastric adenocarcinoma, chemotherapy (e.g., CHOP regimen) is a primary treatment modality, often resulting in excellent regression. * **Option D:** While most gastric lymphomas are of **B-cell origin** (MALT and DLBCL), they are not *essentially* (exclusively) B-cell type [1]. Rare T-cell lymphomas and NK-cell lymphomas can also occur in the stomach, making this statement technically incomplete compared to Option A. **High-Yield Clinical Pearls for NEET-PG:** * **H. pylori Association:** Strongest risk factor for Gastric MALToma [1]. Eradication of *H. pylori* can lead to complete remission in early-stage MALToma. * **Translocation:** MALToma is frequently associated with **t(11;18)(q21;q21)**; patients with this translocation are usually resistant to *H. pylori* eradication therapy. * **Appearance:** On endoscopy, it may mimic a gastric ulcer or "bull’s eye" lesion [2]. * **Staging:** The **Ann Arbor** or **Lugano** classification is used for staging. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 356-357. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 780-781.

Question 290: Histopathological findings in Whipple's disease include all of the following, except:

A. Marked increase in the number of macrophages in the mucosa
B. Marked increase in the number of intraepithelial lymphocytes (Correct Answer)
C. Dilatation of lymphatics in the mucosa
D. Lipid deposition in the mucosa

Explanation: **Explanation:** Whipple’s disease is a rare systemic infectious disease caused by the gram-positive actinomycete **_Tropheryma whipplei_**. The primary pathology involves the infiltration of the small intestinal lamina propria by bulky macrophages, which leads to lymphatic obstruction and malabsorption [1]. **Why Option B is the Correct Answer (The "Except"):** A marked increase in **intraepithelial lymphocytes (IELs)** [2] is a hallmark of **Celiac Disease**, not Whipple’s disease. In Whipple’s disease, the inflammatory infiltrate is predominantly macrophage-driven rather than lymphocytic. **Analysis of Incorrect Options:** * **Option A:** This is a classic finding. The lamina propria is densely packed with large, foamy **macrophages** containing PAS-positive, diastase-resistant granules (representing the partially digested bacilli) [1]. * **Option C:** The massive accumulation of macrophages in the lamina propria causes physical compression and **obstruction of the lymphatics** (lacteals), leading to their dilatation [1]. * **Option D:** Due to the lymphatic obstruction, there is impaired transport of chylomicrons. This results in **lipid deposition** within the mucosa and extracellular spaces, often appearing as "fatty vacuoles" on histology [1]. **NEET-PG High-Yield Pearls:** * **Causative Agent:** *Tropheryma whipplei* [1]. * **Staining:** **PAS (Periodic Acid-Schiff)** positive, **Diastase-resistant** inclusions (bacilli) within macrophages [1]. * **Electron Microscopy:** Shows characteristic **"rod-shaped" bacilli** [1]. * **Clinical Triad:** Malabsorption (diarrhea/weight loss), Migratory polyarthritis, and Lymphadenopathy [1]. * **Differential Diagnosis:** *Mycobacterium avium-intracellulare* (MAI) also shows PAS+ macrophages, but MAI is **Acid-Fast (AFB) positive**, whereas *T. whipplei* is **AFB negative** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 798-799. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 789-790.

Practice by Chapter

Oral Cavity and Esophageal Pathology

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Gastritis and Peptic Ulcer Disease

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Inflammatory Bowel Disease

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Malabsorption Syndromes

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Vascular Disorders of Intestine

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Diverticular Disease

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Intestinal Obstruction

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Gastrointestinal Infections

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Polyps and Neoplasms

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Appendiceal Pathology

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