A 55-year-old female comes to see her doctor for a rapidly enlarging abdomen and swelling of both legs. She was hospitalized 2 weeks ago for an upper gastrointestinal bleeding episode. On that occasion, her esophagogastroduodenoscopy showed grade 1 esophageal varices and a 1 cm clean-based antral ulcer. The patient was discharged on omeprazole. Review of symptoms shows that the patient is forgetful, does not sleep well, and is drowsy and fatigued during the day which prevents her from working full-time. She denies abdominal pain. The patient has a 10-year history of type 2 diabetes mellitus, hypertension, and hypercholesterolemia but no history of angina or coronary heart disease. She drank alcohol moderately heavy in her twenties and currently drinks less than 3 drinks per week and does not smoke. Her family history is unremarkable. On physical examination, her blood pressure is 132/82 mm Hg, pulse is 88/min, and her temperature is 37.0°C (98.6°F). She weighs 106.6 kg (235 lb) and her BMI is 33. She is alert, oriented to person, place, year, and month but not to the day. Her sclerae are nonicteric. Her pulmonary and cardiovascular exam are normal but her abdomen is distended with a fluid wave and mild tenderness to palpation. There is no hepatosplenomegaly. There is a 2+ edema to mid-calf and pedal pulses are barely palpable. Her neurological exam is without motor or sensory deficits but she demonstrates flapping tremor of her hands while asked to hold them in front of her for a few seconds and her skin exam shows a few spider telangiectasias on her face and upper chest. After an initial evaluation, lab tests were obtained:
Serum sodium 133 mEq/L
Serum potassium 3.8 mEq/L
BUN 8 mg/dL
Serum creatinine 1.0 mg/dL
Serum albumin 2.5 mg/dL
Aspartate aminotransferase 68 IU/ml
Alanine aminotransferase 46 IU/ml
Alkaline phosphatase 130 IU/ml
Total bilirubin 1.8 mg/dL
WBC count 4,200/mm3
Platelets 94,000/mm3
Hematocrit 35.5%
Prothrombin time (INR) 1.5
A liver biopsy is performed and the results are pending. The hepatocytes causing her acute issue are predominantly located in which area of the hepatic lobule?
Q32
A 52-year-old Caucasian male presents to your office complaining of black, tarry stool. Which of the following possible causes of this patient's presentation is LEAST associated with the development of carcinoma?
Q33
A 25-year-old male presents to his primary care physician for fatigue, abdominal pain, diarrhea, and weight loss. He states that this issue has occurred throughout his life but seems to “flare up” on occasion. He states that his GI pain is relieved with defecation, and his stools are frequent, large, and particularly foul-smelling. The patient has a past medical history of an ACL tear, as well as a car accident that resulted in the patient needing a transfusion and epinephrine to treat transfusion anaphylaxis. His current medications include vitamin D and ibuprofen. He recently returned from a camping trip in the eastern United States. He states that on the trip they cooked packed meats over an open fire and obtained water from local streams. His temperature is 99.5°F (37.5°C), blood pressure is 120/77 mmHg, pulse is 70/min, respirations are 11/min, and oxygen saturation is 98% on room air. Physical exam reveals poor motor control and an ataxic gait on neurologic exam. Cardiac and pulmonary exams are within normal limits. Laboratory studies are ordered and return as below:
Hemoglobin: 9.0 g/dL
Hematocrit: 25%
Haptoglobin: 12 mg/dL
Leukocyte count: 7,500 cells/mm^3 with normal differential
Platelet count: 255,000/mm^3
Serum:
Na+: 140 mEq/L
Cl-: 102 mEq/L
K+: 5.0 mEq/L
HCO3-: 24 mEq/L
BUN: 24 mg/dL
Glucose: 82 mg/dL
Creatinine: 1.0 mg/dL
Ca2+: 9.0 mg/dL
LDH: 457 U/L
AST: 11 U/L
ALT: 11 U/L
Radiography is ordered which reveals a stress fracture in the patient’s left tibia. Which of the following is the best confirmatory test for this patient’s condition?
Q34
A 59-year-old woman comes to the physician because of a 1-year history of nausea and chronic abdominal pain that is worse after eating. She has Hashimoto thyroiditis. She does not smoke or drink alcohol. A biopsy specimen of the corpus of the stomach shows destruction of the upper glandular layer of the gastric mucosa and G-cell hyperplasia. This patient is at greatest risk for which of the following conditions?
Q35
Two weeks after returning from vacation in Mexico, a 21-year-old man comes to the emergency department because of malaise, nausea, vomiting, fever, and abdominal pain. He has no history of serious illness and takes no medications. Physical examination shows scleral icterus and right upper quadrant tenderness. The liver is palpated 1.5 cm below the right costal margin. A biopsy specimen of this patient's liver would most likely show which of the following findings?
Q36
A 52-year-old man presents with 2 months of diarrhea, abdominal pain, and fatigue. He reports a weight loss of 4 kg (8 lb). He also says his joints have been hurting recently, as well. Past medical history is unremarkable. Review of systems is significant for problems with concentration and memory. Physical examination is unremarkable. A GI endoscopy is performed with a biopsy of the small bowel. Which of the following histologic finding would most likely be seen in this patient?
Q37
A 22-year-old Caucasian female presents with severe right lower quadrant pain, malaise, and diarrhea. The physician performs an endoscopy and finds disease involvement in the terminal ileum, noting that the disease process is patchy with normal intervening mucosa. The entire wall of the region is thickened and inflamed, which may directly lead to formation of:
Q38
A previously healthy 67-year-old man comes to the physician because of a history of recurrent right lower abdominal pain for the past 2 years. A CT scan shows a 1.2-cm (0.47-in) mass located in the terminal ileum. He undergoes surgical removal of the mass. A photomicrograph of the resected specimen is shown. Cells from this tissue are most likely to stain positive for which of the following?
Q39
An otherwise healthy 56-year-old man comes to the physician for a 2-year history of recurrent upper abdominal pain and fullness that worsens after meals. Urea breath test is positive. An endoscopy shows diffuse mucosal atrophy and patchy erythema, but no ulcer. A biopsy from which of the following areas is most likely to yield an accurate diagnosis?
Q40
A 13-year-old boy presents to the emergency department with severe right-lower-quadrant abdominal pain. Workup reveals acute appendicitis, and he subsequently undergoes laparoscopic appendectomy. The appendix is sent for histological examination. A pathologist reviews the slide shown in the image below. Which statement about the structures marked within the yellow circles is correct?
GI US Medical PG Practice Questions and MCQs
Question 31: A 55-year-old female comes to see her doctor for a rapidly enlarging abdomen and swelling of both legs. She was hospitalized 2 weeks ago for an upper gastrointestinal bleeding episode. On that occasion, her esophagogastroduodenoscopy showed grade 1 esophageal varices and a 1 cm clean-based antral ulcer. The patient was discharged on omeprazole. Review of symptoms shows that the patient is forgetful, does not sleep well, and is drowsy and fatigued during the day which prevents her from working full-time. She denies abdominal pain. The patient has a 10-year history of type 2 diabetes mellitus, hypertension, and hypercholesterolemia but no history of angina or coronary heart disease. She drank alcohol moderately heavy in her twenties and currently drinks less than 3 drinks per week and does not smoke. Her family history is unremarkable. On physical examination, her blood pressure is 132/82 mm Hg, pulse is 88/min, and her temperature is 37.0°C (98.6°F). She weighs 106.6 kg (235 lb) and her BMI is 33. She is alert, oriented to person, place, year, and month but not to the day. Her sclerae are nonicteric. Her pulmonary and cardiovascular exam are normal but her abdomen is distended with a fluid wave and mild tenderness to palpation. There is no hepatosplenomegaly. There is a 2+ edema to mid-calf and pedal pulses are barely palpable. Her neurological exam is without motor or sensory deficits but she demonstrates flapping tremor of her hands while asked to hold them in front of her for a few seconds and her skin exam shows a few spider telangiectasias on her face and upper chest. After an initial evaluation, lab tests were obtained:
Serum sodium 133 mEq/L
Serum potassium 3.8 mEq/L
BUN 8 mg/dL
Serum creatinine 1.0 mg/dL
Serum albumin 2.5 mg/dL
Aspartate aminotransferase 68 IU/ml
Alanine aminotransferase 46 IU/ml
Alkaline phosphatase 130 IU/ml
Total bilirubin 1.8 mg/dL
WBC count 4,200/mm3
Platelets 94,000/mm3
Hematocrit 35.5%
Prothrombin time (INR) 1.5
A liver biopsy is performed and the results are pending. The hepatocytes causing her acute issue are predominantly located in which area of the hepatic lobule?
A. The zone receiving the most oxygenated blood from the hepatic artery
B. The zone where gluconeogenesis is predominant
C. The zone involved in cholesterol synthesis
D. The zone closest to the centrolobular vein (Correct Answer)
E. The zone with little or no cytochrome P450 enzymes
Explanation: ***The zone closest to the centrolobular vein***
- This zone, known as **Zone 3** or the **centrilobular zone**, is the furthest from the hepatic arteriole and portal venule, making it the most vulnerable to **hypoxic injury** and **metabolic stress**. The patient's presentation with advanced liver disease (ascites, pedal edema, coagulopathy, encephalopathy, spider angiomata) suggests significant hepatocellular damage.
- Given her **metabolic risk factors** (obesity, type 2 diabetes, hypercholesterolemia) and minimal alcohol use, this patient most likely has **Non-Alcoholic Steatohepatitis (NASH)** progressing to cirrhosis. NASH predominantly affects **Zone 3 hepatocytes** due to their lower oxygen tension and higher susceptibility to lipotoxicity and oxidative stress.
- Zone 3 hepatocytes also have high concentrations of **cytochrome P450 enzymes** involved in drug and toxin metabolism, making them vulnerable to toxic metabolites and metabolic injury.
*The zone receiving the most oxygenated blood from the hepatic artery*
- This refers to **Zone 1** (periportal zone), which is highly oxygenated and supplied by the hepatic arteriole. This zone is generally more resistant to hypoxic and metabolic injury.
- **Zone 1** is primarily involved in oxidative metabolism, gluconeogenesis, and urea synthesis, and is most affected by viral hepatitis and cholestasis, not typically the primary site of damage in NASH-related cirrhosis.
*The zone where gluconeogenesis is predominant*
- **Zone 1** (periportal zone) is where gluconeogenesis is most active due to its high oxygen supply and proximity to incoming nutrients from the portal vein.
- While important for liver function, this zone is typically not the primary site of damage in metabolic liver disease leading to end-stage manifestations like those described in this patient.
*The zone involved in cholesterol synthesis*
- **Cholesterol synthesis** occurs throughout hepatocytes with some distribution across zones. This option does not specifically identify the zone most susceptible to **damage** in metabolic liver disease.
- The question concerns the zone most predominantly affected by the type of injury causing the patient's acute decompensation, which is Zone 3.
*The zone with little or no cytochrome P450 enzymes*
- **Zone 3** (centrilobular zone) actually has the **highest concentration** of **cytochrome P450 enzymes**, making it susceptible to damage from toxic metabolites and metabolic stress.
- **Zone 1** has the lowest concentration of these enzymes. Therefore, this statement is factually incorrect and represents the opposite of the correct answer.
Question 32: A 52-year-old Caucasian male presents to your office complaining of black, tarry stool. Which of the following possible causes of this patient's presentation is LEAST associated with the development of carcinoma?
A. Adenomatous polyp
B. H. pylori infection
C. Gastric ulcer
D. Barrett's esophagus
E. Duodenal ulcer (Correct Answer)
Explanation: ***Duodenal ulcer***
- While duodenal ulcers can cause **melena** due to upper GI bleeding, they are **rarely associated with an increased risk of carcinoma**.
- They typically result from **H. pylori infection** or NSAID use, and the duodenal mucosa has a very low propensity for malignant transformation.
*Adenomatous polyp*
- **Adenomatous polyps** are considered **premalignant lesions** and are strongly associated with the development of colorectal carcinoma.
- The risk of malignancy increases with polyp size, villous histology, and degree of dysplasia.
*H. pylori infection*
- **Chronic H. pylori infection** is a major risk factor for several gastric malignancies, including **gastric adenocarcinoma** and **MALT lymphoma**.
- It causes chronic inflammation, leading to atrophy, intestinal metaplasia, and dysplasia, which are precursors to cancer.
*Gastric ulcer*
- While most gastric ulcers are benign, a significant proportion (especially those not resolving with treatment) can be **malignant (gastric adenocarcinoma)**.
- H. pylori infection and NSAID use are common causes for both benign and malignant gastric ulcers, and all gastric ulcers require follow-up to rule out malignancy.
*Barrett's esophagus*
- **Barrett's esophagus** is a premalignant condition where the normal stratified squamous epithelium of the esophagus is replaced by intestinal columnar epithelium.
- It is a major risk factor for the development of **esophageal adenocarcinoma**, with the risk increasing with the degree of dysplasia.
Question 33: A 25-year-old male presents to his primary care physician for fatigue, abdominal pain, diarrhea, and weight loss. He states that this issue has occurred throughout his life but seems to “flare up” on occasion. He states that his GI pain is relieved with defecation, and his stools are frequent, large, and particularly foul-smelling. The patient has a past medical history of an ACL tear, as well as a car accident that resulted in the patient needing a transfusion and epinephrine to treat transfusion anaphylaxis. His current medications include vitamin D and ibuprofen. He recently returned from a camping trip in the eastern United States. He states that on the trip they cooked packed meats over an open fire and obtained water from local streams. His temperature is 99.5°F (37.5°C), blood pressure is 120/77 mmHg, pulse is 70/min, respirations are 11/min, and oxygen saturation is 98% on room air. Physical exam reveals poor motor control and an ataxic gait on neurologic exam. Cardiac and pulmonary exams are within normal limits. Laboratory studies are ordered and return as below:
Hemoglobin: 9.0 g/dL
Hematocrit: 25%
Haptoglobin: 12 mg/dL
Leukocyte count: 7,500 cells/mm^3 with normal differential
Platelet count: 255,000/mm^3
Serum:
Na+: 140 mEq/L
Cl-: 102 mEq/L
K+: 5.0 mEq/L
HCO3-: 24 mEq/L
BUN: 24 mg/dL
Glucose: 82 mg/dL
Creatinine: 1.0 mg/dL
Ca2+: 9.0 mg/dL
LDH: 457 U/L
AST: 11 U/L
ALT: 11 U/L
Radiography is ordered which reveals a stress fracture in the patient’s left tibia. Which of the following is the best confirmatory test for this patient’s condition?
A. Stool ELISA
B. Vitamin B12 and folate level
C. Vitamin E level (Correct Answer)
D. Bowel wall biopsy
E. Iron studies
Explanation: ***Vitamin E level***
- The patient's presentation suggests **celiac disease** causing **malabsorption** with secondary **vitamin E deficiency**, which is causing the specific complications seen here.
- The **neurological findings** of **ataxic gait** and **poor motor control** combined with **hemolytic anemia** (low haptoglobin 12 mg/dL, elevated LDH 457 U/L, anemia) are **pathognomonic for vitamin E deficiency**.
- Vitamin E deficiency causes **spinocerebellar degeneration**, **peripheral neuropathy**, and **hemolytic anemia** due to oxidative damage to RBC membranes and neuronal lipids.
- The **stress fracture** suggests bone disease from calcium/vitamin D malabsorption, but the neuro-hematologic picture is most specific for vitamin E.
- **Serum vitamin E level** is the **confirmatory test** for this specific deficiency syndrome causing the patient's neurological and hematological complications.
- While the underlying condition is likely celiac disease, confirming vitamin E deficiency directly explains the constellation of findings and guides immediate treatment.
*Bowel wall biopsy*
- A **small intestine biopsy** would confirm the underlying diagnosis of **celiac disease** (villous atrophy, crypt hyperplasia) causing the malabsorption.
- However, the question asks for confirmation of "this patient's condition" - referring to the specific syndrome presenting with the characteristic triad of **ataxia + hemolysis + malabsorption**.
- This triad is pathognomonic for **vitamin E deficiency**, making direct measurement more confirmatory for the presenting complication than tissue diagnosis of the underlying cause.
*Vitamin B12 and folate level*
- **Vitamin B12 deficiency** can cause **subacute combined degeneration** with ataxia and neurological symptoms, but typically presents with **posterior column signs** (loss of proprioception, vibration) and **peripheral neuropathy**, not primarily cerebellar ataxia.
- **Folate deficiency** causes **megaloblastic anemia** but does **not** cause neurological deficits or the hemolytic pattern seen here (low haptoglobin, elevated LDH with normal liver enzymes).
- The **hemolytic anemia** is specific to vitamin E deficiency, not B12/folate deficiency.
*Stool ELISA*
- Could detect **Giardia lamblia** given the history of drinking stream water during camping, which can cause acute diarrhea and malabsorption.
- However, this does not explain the **lifelong, recurring symptoms**, **neurological deficits**, **hemolytic anemia**, or **stress fracture**.
- The chronic nature points to a primary malabsorption disorder, not acute infection.
*Iron studies*
- **Iron deficiency** commonly occurs with celiac disease due to duodenal malabsorption and could contribute to the **anemia**.
- However, iron deficiency causes **microcytic anemia**, not hemolytic anemia, and does **not** explain the **low haptoglobin**, **elevated LDH**, **ataxic gait**, or **motor control issues**.
- These findings are specific to vitamin E deficiency.
Question 34: A 59-year-old woman comes to the physician because of a 1-year history of nausea and chronic abdominal pain that is worse after eating. She has Hashimoto thyroiditis. She does not smoke or drink alcohol. A biopsy specimen of the corpus of the stomach shows destruction of the upper glandular layer of the gastric mucosa and G-cell hyperplasia. This patient is at greatest risk for which of the following conditions?
A. Aplastic anemia
B. Gastric adenocarcinoma (Correct Answer)
C. Duodenal perforation
D. Curling ulcer
E. Gastric MALT lymphoma
Explanation: ***Gastric adenocarcinoma***
- The biopsy findings of **destruction of the upper glandular layer** and **G-cell hyperplasia** are classic for **Autoimmune Metaplastic Atrophic Gastritis (AMAG)**, which is a significant risk factor for **gastric adenocarcinoma**.
- AMAG leads to **intestinal metaplasia** and **dysplasia** over time, increasing the risk of malignant transformation; her history of **Hashimoto thyroiditis** further supports an autoimmune predisposition.
*Aplastic anemia*
- This condition involves bone marrow failure leading to **pancytopenia** and is not directly linked to autoimmune gastritis or the gastric biopsy findings described.
- While some autoimmune conditions can be associated with aplastic anemia, the direct causal link from AMAG to aplastic anemia is not as strong as the link to gastric cancer.
*Duodenal perforation*
- This is an acute complication typically associated with **peptic ulcer disease** (e.g., from H. pylori infection or NSAID use), not directly with autoimmune gastritis.
- The presented symptoms and biopsy findings do not indicate a high risk of duodenal perforation.
*Curling ulcer*
- A **Curling ulcer** is a type of acute **stress ulcer** that develops in patients with severe burns due to hypovolemia and resultant splanchnic vasoconstriction.
- The patient's presentation of chronic symptoms and specific biopsy findings do not align with the etiology of a Curling ulcer.
*Gastric MALT lymphoma*
- **MALT lymphoma** is predominantly associated with chronic **H. pylori infection**, which leads to acquired chronic gastritis, not typically autoimmune gastritis.
- While chronic inflammation is involved, the specific biopsy findings (destruction of upper glandular layer, G-cell hyperplasia) point more strongly to AMAG and its associated risks than to MALT lymphoma.
Question 35: Two weeks after returning from vacation in Mexico, a 21-year-old man comes to the emergency department because of malaise, nausea, vomiting, fever, and abdominal pain. He has no history of serious illness and takes no medications. Physical examination shows scleral icterus and right upper quadrant tenderness. The liver is palpated 1.5 cm below the right costal margin. A biopsy specimen of this patient's liver would most likely show which of the following findings?
A. Piecemeal necrosis and fatty changes
B. Lymphocytic infiltration and progressive ductopenia
C. Ballooning degeneration and bridging necrosis (Correct Answer)
D. Ground glass hepatocytes and apoptotic bodies
E. Dysplastic hepatocytes with intracellular bile
Explanation: ***Ballooning degeneration and bridging necrosis***
- The patient presents with symptoms and signs of **acute viral hepatitis**, characterized by malaise, nausea, vomiting, fever, abdominal pain, scleral icterus, and right upper quadrant tenderness following travel to an endemic area (Mexico). **Ballooning degeneration** of hepatocytes and **bridging necrosis** (necrosis extending between portal tracts and central veins) are classic histological features of severe acute viral hepatitis.
- These findings reflect the **cytopathic effect of the virus** and the host's immune response, leading to hepatocyte injury and extensive liver damage.
*Piecemeal necrosis and fatty changes*
- **Piecemeal necrosis** (also known as interface hepatitis) is characteristic of **chronic hepatitis**, where inflammation at the portal-parenchymal interface leads to destruction of periportal hepatocytes, not typical for acute resolving hepatitis.
- **Fatty changes** (steatosis) are commonly seen in conditions like **alcoholic liver disease** or **non-alcoholic fatty liver disease (NAFLD)**, and are not primary features of acute viral hepatitis.
*Lymphocytic infiltration and progressive ductopenia*
- **Lymphocytic infiltration** is a general feature of many forms of hepatitis, but **progressive ductopenia** (loss of bile ducts) is highly suggestive of **primary biliary cholangitis (PBC)**, an autoimmune condition, or **primary sclerosing cholangitis (PSC)**, which does not fit the acute presentation or travel history.
- These conditions are typically chronic and have different clinical manifestations.
*Ground glass hepatocytes and apoptotic bodies*
- **Ground-glass hepatocytes** are a hallmark feature of **chronic hepatitis B infection**, indicating the accumulation of HBsAg in the endoplasmic reticulum. This is not typical for acute viral hepatitis where the virus may still be replicating rapidly.
- While **apoptotic bodies** (Councilman bodies) can be seen in acute hepatitis, they are not the predominant or most specific finding to describe the widespread damage seen with ballooning degeneration and necrosis.
*Dysplastic hepatocytes with intracellular bile*
- **Dysplastic hepatocytes** are indicative of **precancerous changes** or **hepatocellular carcinoma (HCC)**, usually occurring in the context of chronic liver disease, not acute self-limiting hepatitis.
- While **intracellular bile** might be seen in cholestatic conditions, the combination of dysplastic hepatocytes points away from acute viral hepatitis.
Question 36: A 52-year-old man presents with 2 months of diarrhea, abdominal pain, and fatigue. He reports a weight loss of 4 kg (8 lb). He also says his joints have been hurting recently, as well. Past medical history is unremarkable. Review of systems is significant for problems with concentration and memory. Physical examination is unremarkable. A GI endoscopy is performed with a biopsy of the small bowel. Which of the following histologic finding would most likely be seen in this patient?
A. PAS positive macrophages (Correct Answer)
B. Non-caseating granulomas in the small intestine
C. Absence of nerves in the myenteric plexus
D. Blunting of the villi
E. Crypt hyperplasia with increased intraepithelial lymphocytes
Explanation: **PAS positive macrophages**
- The clinical presentation with **diarrhea**, abdominal pain, weight loss, joint pain, and **neurological symptoms** (problems with concentration and memory) is classic for **Whipple's disease**.
- **Whipple's disease** is caused by the bacterium **Tropheryma whipplei**, which is characterized histologically by **foamy macrophages** in the lamina propria that stain **positive with Periodic Acid-Schiff (PAS)** due to undigested bacterial cell wall material.
*Non-caseating granulomas in the small intestine*
- **Non-caseating granulomas** are characteristic of **Crohn's disease**, which typically presents with abdominal pain, diarrhea, and weight loss, but **neurological symptoms** are not a primary feature.
- While Crohn's disease can cause joint pain (arthritis), the combination of GI and neurological symptoms points away from it.
*Absence of nerves in the myenteric plexus*
- An **absence of nerves in the myenteric plexus** is the hallmark of **Hirschsprung's disease**, which is a congenital disorder primarily affecting neonates and infants, causing intestinal obstruction and chronic constipation.
- This finding is inconsistent with the patient's age and presenting symptoms of diarrhea and neurological issues.
*Blunting of the villi*
- **Villi blunting** is characteristic of **celiac disease** (gluten-sensitive enteropathy), which presents with malabsorption symptoms like diarrhea, weight loss, and abdominal pain.
- However, **celiac disease** typically does not involve **neurological symptoms** like concentration and memory problems as a prominent feature, and the PAS-positive macrophages are specific to Whipple's.
*Crypt hyperplasia with increased intraepithelial lymphocytes*
- **Crypt hyperplasia** and **increased intraepithelial lymphocytes (IELs)** are seen in various small bowel pathologies, including **celiac disease** and **microscopic colitis**.
- While these findings suggest intestinal inflammation, they are not specific to **Whipple's disease** and do not account for the characteristic neurological involvement.
Question 37: A 22-year-old Caucasian female presents with severe right lower quadrant pain, malaise, and diarrhea. The physician performs an endoscopy and finds disease involvement in the terminal ileum, noting that the disease process is patchy with normal intervening mucosa. The entire wall of the region is thickened and inflamed, which may directly lead to formation of:
A. Paneth cell metaplasia
B. Toxic megacolon
C. Plummer-Vinson syndrome
D. Widening of the intestinal lumen
E. Fistulas (Correct Answer)
Explanation: ***Fistulas***
- **Transmural inflammation**, characteristic of **Crohn's disease**, means the entire wall of the intestine is affected, leading to deep ulcerations and sinus tracts that can bore through tissues.
- This deep, penetrating inflammation often results in the formation of **fistulas** (abnormal connections between organs or to the skin) or **abscesses**.
*Paneth cell metaplasia*
- This is a histological change where **Paneth cells**, normally found in the small intestine, appear in regions they shouldn't, such as the colon.
- While it can occur in **inflammatory bowel disease**, it is a microscopic change and not a direct consequence of the described gross pathology (transmural inflammation leading to a larger structural complication like a fistula).
*Toxic megacolon*
- This is a severe complication characterized by **colonic dilation** and systemic toxicity, usually seen in **ulcerative colitis**, not typically Crohn's disease limited to the terminal ileum.
- It arises from acute, severe inflammation that extends to the muscularis propria, causing paralysis of the colon, which is distinct from the **transmural inflammation** in Crohn's leading to fistulas.
*Plummer-Vinson syndrome*
- This syndrome is characterized by a triad of **iron-deficiency anemia**, **dysphagia** (due to esophageal webs), and **glossitis**, which is unrelated to inflammatory bowel disease.
- It is a condition of the upper gastrointestinal tract and has no direct link to the pathology described in the terminal ileum.
*Widening of the intestinal lumen*
- The **transmural inflammation** described in Crohn's disease typically leads to **thickening of the bowel wall** and, more commonly, **strictures** (narrowing) of the lumen rather than widening.
- The inflammatory process usually causes fibrosis and scarring, which reduces the luminal diameter, particularly in chronic disease.
Question 38: A previously healthy 67-year-old man comes to the physician because of a history of recurrent right lower abdominal pain for the past 2 years. A CT scan shows a 1.2-cm (0.47-in) mass located in the terminal ileum. He undergoes surgical removal of the mass. A photomicrograph of the resected specimen is shown. Cells from this tissue are most likely to stain positive for which of the following?
A. Desmin
B. Chromogranin A (Correct Answer)
C. Glial fibrillary acid protein
D. Cytokeratin
E. Vimentin
Explanation: ***Chromogranin A***
- The presentation of a recurrent right lower abdominal pain with a mass in the **terminal ileum** in an elderly patient is highly suggestive of a **neuroendocrine tumor (NET)**, often referred to as a carcinoid tumor.
- **Chromogranin A** is a common and reliable **immunohistochemical marker** for neuroendocrine differentiation, making it the most likely positive stain for cells from such a tumor.
*Desmin*
- **Desmin** is an intermediate filament typically found in **muscle cells** (smooth, skeletal, and cardiac).
- While the gastrointestinal tract contains smooth muscle, a primary neuroendocrine tumor would not typically stain positive for desmin.
*Glial fibrillary acid protein*
- **Glial fibrillary acid protein (GFAP)** is an intermediate filament protein primarily found in **astrocytes** and other glial cells of the central nervous system.
- It is not a marker for neuroendocrine tumors or gastrointestinal neoplasms.
*Cytokeratin*
- **Cytokeratin** is a family of intermediate filament proteins found in **epithelial cells** and is a marker for carcinomas (epithelial cancers).
- While NETs originate from neuroepithelial cells, they have distinct markers like chromogranin and synaptophysin that differentiate them from typical carcinomas, though some NETs can show focal cytokeratin positivity.
*Vimentin*
- **Vimentin** is an intermediate filament protein found in **mesenchymal cells** (e.g., fibroblasts, endothelial cells, adipocytes).
- It is not a primary marker for neuroendocrine tumors; instead, it is often used to identify sarcomas or other mesenchymal neoplasms.
Question 39: An otherwise healthy 56-year-old man comes to the physician for a 2-year history of recurrent upper abdominal pain and fullness that worsens after meals. Urea breath test is positive. An endoscopy shows diffuse mucosal atrophy and patchy erythema, but no ulcer. A biopsy from which of the following areas is most likely to yield an accurate diagnosis?
A. Gastric pylorus
B. Gastric fundus
C. Gastric antrum (Correct Answer)
D. Distal esophagus
E. Duodenal bulb
Explanation: ***Gastric antrum***
- The patient's symptoms (recurrent upper abdominal pain, fullness worsening after meals), positive **urea breath test**, and endoscopic findings (mucosal atrophy, patchy erythema) are highly suggestive of **Helicobacter pylori infection** causing gastritis.
- **H. pylori** preferentially colonizes the **gastric antrum**, making this the most appropriate site for biopsy to confirm the diagnosis and assess the extent of inflammation and atrophy.
*Gastric pylorus*
- While the pylorus is part of the stomach, the **antrum** is the primary site of H. pylori colonization and inflammation.
- Biopsies from the pylorus might show some changes but are less likely to be diagnostic than those from the antrum.
*Gastric fundus*
- The gastric fundus is typically **spared** in initial H. pylori infections, which primarily affect the antrum and corpus.
- Biopsy from this area would be **less likely** to yield an accurate diagnosis of H. pylori-associated gastritis compared to the antrum.
*Distal esophagus*
- The distal esophagus is primarily affected by conditions like **gastroesophageal reflux disease (GERD)** or **Barrett's esophagus**, which are not indicated by the patient's symptoms or positive urea breath test.
- H. pylori does not colonize the esophagus, so a biopsy here would be **uninformative** for this suspected diagnosis.
*Duodenal bulb*
- The duodenal bulb can be affected by **H. pylori-associated duodenitis** or **duodenal ulcers**, often secondary to increased acid production driven by antral H. pylori.
- However, the primary site of infection and the most reliable location for initial diagnosis of H. pylori gastritis itself remains the **gastric antrum**.
Question 40: A 13-year-old boy presents to the emergency department with severe right-lower-quadrant abdominal pain. Workup reveals acute appendicitis, and he subsequently undergoes laparoscopic appendectomy. The appendix is sent for histological examination. A pathologist reviews the slide shown in the image below. Which statement about the structures marked within the yellow circles is correct?
A. These structures belong to the primary lymphatic system.
B. These structures are not normally present within the appendix.
C. The only part of the digestive system in which this structure can be found is the appendix.
D. In children, appendicitis can frequently arise from certain changes in these structures. (Correct Answer)
E. Neutrophils are the major components of these structures.
Explanation: **In children, appendicitis can frequently arise from certain changes in these structures.**
- The structures marked (assuming they are **lymphoid follicles**) in the appendix are prominent in children and play a role in **mucosal immunity**.
- **Lymphoid hyperplasia**, an enlargement of these follicles, is a common cause of appendicitis in children as it can obstruct the narrow appendiceal lumen.
*These structures belong to the primary lymphatic system.*
- The structures (lymphoid follicles) found in the appendix are part of the **secondary (peripheral) lymphatic system**, where lymphocytes encounter antigens and mount immune responses.
- **Primary lymphatic organs** (e.g., bone marrow and thymus) are where lymphocytes mature, not where they mainly function in antigen presentation.
*These structures are not normally present within the appendix.*
- **Lymphoid follicles** are a normal and characteristic feature of the appendix, especially in children and young adults.
- The appendix is considered a lymphoid organ and is rich in **gut-associated lymphoid tissue (GALT)**.
*The only part of the digestive system in which this structure can be found is the appendix.*
- While prominent in the appendix, lymphoid follicles are found throughout the **gastrointestinal tract**, including the Peyer's patches in the ileum.
- These structures are crucial for **mucosal immune surveillance** in various parts of the digestive system.
*Neutrophils are the major components of these structures.*
- The primary cellular components of **lymphoid follicles** are **B lymphocytes** (B cells), which are responsible for humoral immunity, and some T cells.
- **Neutrophils** are primarily involved in acute inflammation and are present in lymphoid tissue only when there is an infection or inflammatory process.