TABLE IV-114 Risk Factors for Active Tuberculosis Among Persons Who Have Been Infected With Tubercle Bacilli 18 page
VII-11. The answer is B. (Chap. 280) Anemia is a common consequence of chronic kidney disease and may be multifactorial, with etiologies including relative erythropoietin deficiency, iron deficiency, chronic inflammation, diminished red cell survival, and bleeding diathesis. Several trials of erythropoietin supplementation in patients with chronic kidney disease have failed to show improved cardiovascular outcomes with this therapy. Indeed, these trials have shown a higher incidence of thromboembolic events, stroke in Type 2 diabetics, and potentially faster progression to need for dialysis. Because of these concerning findings, erythropoietin use has been altered from prior recommendations, and current practice is to target a hemoglobin concentration of 100–115 g/L.
VII-12. The answer is B. (Chap. 281) The commonly accepted criteria for initiating patients on maintenance dialysis include the presence of uremic symptoms, the presence of hyper-kalemia unresponsive to conservative management, persistent extracellular volume expansion despite diuretics, acidosis refractory to medical therapy, bleeding diathesis, or a creatinine clearance or estimated GFR below 10 mL/min per 1.73m2. BUN or creatinine values alone are inadequate to initiate dialysis.
VII-13. The answer is E. (Chap. 281) Hypotension is the most common complication of hemodialysis. There are many potential etiologies of hypotension including antihypertensive use, excessive ultrafiltration, impaired vasoactive or autonomic responses, impaired cardiac reserve, and osmolar shifts. Less common causes include dialyzer reactions and high-output heart failure related to large arteriovenous (AV) fistulae. Manipulation of buffer for dialysate, alterations of timing of ultrafiltration, and midodrine may be used to improve hemodynamic tolerance to hemodialysis. Patients with unexpected or new hypotension during stable dialysis should also be evaluated for graft infection and
bacteremia.
VII-14. The answer is E. (Chap. 281) The major complication of peritoneal dialysis therapy is peritonitis, though other complications include catheter-associated non-peritonitis infections, weight gain, metabolic derangements, and residual uremia. Peritonitis is usually a result from a failure of sterile technique during the exchange procedure. Transvisceral infection from the bowel is much less common. Because of the high dextrose used in dialysate, the environment is conducive for the development of bacterial infection. This can be diagnosed by the presence of more than 100/mm3 leukocytes with more than 50% polymorphonuclear cells on microscopy. Cloudy dialysate and abdominal pain are the most common symptoms. The most commonly isolated bacteria are skin flora such as Staphylococcus. Gram-negative organisms, fungi, and mycobacteria have also been described. A recent Cochrane review (Wiggins KJ et al: Treatment for peritoneal dialysis-associated peritonitis. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD005284. DOI: 10.1002/14651858.CD005284.pub2) concluded that intraperitoneal administration of antibiotics was more effective than intravenous administration, and that adjunctive treatment with urokinase or peritoneal lavage offers no advantage. Intraperito-neal vancomycin is common initial empiric therapy.
VII-15. The answer is C. (Chap. 281) The most common cause of mortality in patients with end-stage renal disease is cardiovascular disease (stroke and myocardial infarction). Although the underlying mechanisms driving this association are under active investigation, the shared risk factors of diabetes, hypertension, and dyslipidemia in addition to specific risks such as increased inflammation, hyperhomocysteinemia, anemia, and altered vascular function are thought to play an important role. Inefficient or inadequate dialysis is a risk for patients with difficult vascular access or poor adherence to therapy. Patients receiving hemodialysis are at risk and often develop neurologic, hematologic, and infectious complications. Nevertheless, the biggest risk to survival in these patients is also the most common cause of death in the general population.
VII-16. The answer is B. (Chap. 281) Although the dose is currently defined as a derivation of the fractional urea clearance, factors that are also important include patient size, residual kidney function, dietary protein intake, comorbid conditions, and the degree of anabolism/catabolism. The efficiency of dialysis depends on the counter-current flow rate of the dialysate. The number of hours/sessions prescribed for a patient is derived from the dialysis dose and is individualized.
VII-17. The answer is A. (Chap. 281) The potassium concentration of dialysate is usually 2.5 meq/L but may be varied depending on the predialysis serum potassium. This patient may need a lower dialysate potassium concentration. Sodium modeling is an adjustment of the dialysate sodium that may lessen the incidence of hypotension at the end of a dialysis session. Aldosterone defects, if present, are not likely to play a role in this patient since his kidneys are not being perfused. Therefore, nephrectomy is not likely to control his potassium. Similarly, since the patient is likely anuric, there is no efficacy in utilizing loop diuretics to effect kaluresis. This patient has no approved indications for implantation of a defibrillator.
VII-18. The answer is D. (Chap. 282) Both deceased and living donor kidney transplantations are highly successful. When compared to hemodialysis there are substantial cost-benefit advantages to individuals and society related to decreased morbidity, subsequent hospitalizations, and mortality. When first-degree relatives are donors, the graft survival rates are higher than those of deceased donors by 5–7%
at 1 year. This difference persists for up to 10 years. There are few reported complications for donors, particularly in the absence of hypertension or diabetes mellitus. For deceased donors, older age, the presence of preexisting renal damage, or prolonged ischemia decreases the longevity of the graft.
VII-19. The answer is B. (Chap. 283) There are a wide variety of diseases that can cause glomerular injury to the kidney, ranging from genetic conditions such as TRPC6 mutation causing cation channel dysfunction and associated focal segmental glomerulosclerosis to glomerular stress from systemic hypertension and/or diabetes mellitus. Inflammatory disease such as lupus nephritis, Wegener’s granulomatosis, and poststreptococcal glomerulonephritis may also cause glomerular disease. Fanconi’s syndrome is a classic disease of tubular dysfunction with associated aminoaciduria, type 2 renal tubular acidosis, and rickets, not glomerular disease.
VII-20. The answer is C. (Chap. 283) The hallmark of glomerular renal disease is microscopic hematuria and proteinuria. IgA nephropathy and sickle cell disease are the exception to this when gross hematuria may be present. Proteinuria may be heavy (>3 g/24 hours) or lower quantity with microalbuminuria (30–300 mg/24 hours) depending on the underlying disease or site of the immune lesion. Patients with post-streptococcal glomerulonephritis often have pyuria, but cultures are not expected to be positive as the infection is usually skin or mucosal, and it is the immune reaction that drives the renal lesion.
VII-21. The answer is B. (Chap. 283) The characteristic pattern of focal (not all glomeruli) and segmental (not the entire glomerulus) glomerular scarring is shown. The history and laboratory features are also consistent with this lesion: some associated hypertension, diminution in creatinine clearance, and a relatively inactive urine sediment. The “nephropathy of obesity” may be associated with this lesion secondary to hyperfiltration; this condition may be more likely to occur in obese patients with hypoxemia, obstructive sleep apnea, and right-sided heart failure. Hypertensive nephrosclerosis exhibits more prominent vascular changes and patchy, ischemic, totally sclerosed glomeruli. In addition, nephrosclerosis seldom is associated with nephrotic-range proteinuria. Minimal-change disease usually is associated with symptomatic edema and normal-appearing glomeruli, as demonstrated on light microscopy. This patient’s presentation is consistent with that of membranous nephropathy, but the biopsy is not. With membranous glomerular nephritis all glomeruli are uniformly involved with subepithelial dense deposits. There are no features of crescentic glomerulonephritis present.
VII-22. The answer is E. (Chap. 284) Autosomal polycystic kidney disease is a common genetic disorder accounting for up to 4% of end-stage renal disease cases in the United States. Although the most common manifestations of this condition are renal cysts, hematuria, urinary tract infection, and occasionally nephrolithiasis, there are several common extra-renal manifestations including intracranial aneurysm, aortic root and annulus dilatation, valvular heart disease including aortic regurgitation and mitral valve prolapse, hepatic cysts, hernias, and colonic diverticulae with a high propensity to perforate.
VII-23. The answer is C. (Chap. 284) The patient presents with hypokalemia and hypochloremic metabolic alkalosis in the absence of hypertension. This is most commonly due to surreptitious vomiting or diuretic abuse, but in this case the urine diuretic screen was negative. In patients with surreptitious vomiting, urine chloride levels are low to preserve intravascular volume and this was not present in
this patient. Those with Bartter’s syndrome and Gitelman’s syndrome have hypokalemia and hypochloremic metabolic alkalosis with inappropriately elevated urine chloride levels. Gitelman’s syndrome is less severe and presents later in life than Bartter’s, which is commonly found in childhood due to failure to thrive. Additionally, those with Gitelman’s syndrome have more prominent fatigue and muscle cramping. Most forms of Bartter’s syndrome also include associated hypomagnesemia and hypocalciuria. Those with type 1 pseudohypoaldosteronism have severe renal salt wasting and hyperkalemia. Liddle’s syndrome presents with apparent aldosterone excess with severe hypertension, hypokalemia, and metabolic alkalosis.
VII-24. The answer is E. (Chap. 284) Patients with autosomal dominant polycystic kidney disease have a two- to fourfold increased risk of subarachnoid or cerebral hemorrhage compared to the general population. Hemorrhage tends to occur before age 50 in patients with a family history of intracranial hemorrhage, patients with a personal history of intracranial hemorrhage, aneurysms larger than 10 mm, or patients with uncontrolled hypertension.
VII-25. The answer is A. (Chap. 284) This patient has a normal anion gap metabolic acidosis (anion gap = 12). The calculated urine anion gap (Na+ + K+ - Cl-) is +3; thus the acidosis is unlikely to be due to gastrointestinal bicarbonate loss. In this patient the diagnosis is type I renal tubular acidosis, or distal RTA. This is a disorder in which the distal nephron does not lower pH normally. It is associated with a urine pH greater than 5.5, hypokalemia, and lack of bicarbonaturia. This condition may be associated with calcium phosphate stones and nephrocalcinosis. Type II RTA, or proximal RTA, includes a pH less than 5.5, hypokalemia, a positive urine anion gap, bicarbonaturia, hypophosphatemia, and hyper-calciuria. This condition results from the defective resorption of bicarbonate. Type III RTA is rare and most commonly is seen in children. Type IV RTA is also referred to as hyperkalemic distal RTA. Hyporeninemic hypoaldosteronism is the most common cause of type IV RTA and is usually associated with diabetic nephropathy.
VII-26. The answer is D. (Chap. 284) In any patient with hypokalemia the use of diuretics must be excluded. This patient has multiple warning signs for the use of agents to alter her weight, including her age, gender, and participation in competitive sports. Her BMI is low, and the oral examination may suggest chronic vomiting. Chronic vomiting may be associated with a low urine chloride level. Once diuretic use and vomiting are excluded, the differential diagnosis of hypokalemia and metabolic alkalosis includes magnesium deficiency, Liddle’s syndrome, Bartter’s syndrome, and Gitelman’s syndrome. Liddle’s syndrome is associated with hypertension and undetectable aldosterone and renin levels. It is a rare autosomal-dominant disorder. Classic Bartter’s syndrome has a presentation similar to that of this patient. It may also include polyuria and nocturia because of hypokalemia-induced diabetes insipidus. Gitelman’s syndrome can be distinguished from Bartter’s syndrome by hypomagnesemia and hypocalciuria.
VII-27. The answer is A. (Chap. 285) Acute interstitial nephritis is a common cause of both acute and chronic kidney dysfunction. Many causes of interstitial nephritis are successfully treated with glucocorticoids with improved rates of long-term renal recovery including Sjögren’s syndrome, sarcoidosis, systemic lupus erythematosus, adults with tubulointerstitial nephritis with uveitis, and idiopathic or other granulomatous interstitial nephritis. In patients with gradually progressive disease or fibrosis on biopsy, the benefit is less clear. Additionally, allergic interstitial nephritis recovery may
be accelerated with glucocorticoid therapy, but long-term renal recovery has not been proven to improve. Postinfectious interstitial nephritis has been associated with many bacterial and viral pathogens, but generally resolves with treatment of the underlying condition.
VII-28. The answer is E. (Chap. 285) Allergic interstitial nephritis is a common cause of unexplained acute renal failure. This is generally a clinical diagnosis with acute renal failure in the context of exposure to a potential offending agent (often NSAIDs, antibiotics, anticonvulsants, or proton pump inhibitors) and improvement in renal function with withdrawal of the agent. Peripheral blood eosinophilia supports the diagnosis, but is rarely found. Urine microscopy often shows white blood cell casts and hematuria, but these are not specific findings. Urine eosinophils are neither sensitive nor specific for allergic interstitial nephritis. A renal biopsy is generally not required but may show extensive tubulointerstitial infiltration of white cells including eosinophils.
VII-29. The answer is A. (Chap. 286) The patient presents with the classic pentad for thrombotic thrombocytopenic purpura (TTP), including fever, neurologic findings, renal failure, hemolytic anemia, and thrombocytopenia. This condition is more common in women than men, and in black than white patients, and may be triggered by a number of factors including pregnancy, infection, surgery, and pancreatitis. Several drugs have been implicated in the pathogenesis of TTP such as immunosuppressive agents, chemo-therapeutic agents, and antiplatelet drugs. TTP may be differentiated from hemolytic uremic syndrome (HUS) by the demographics, with HUS typically affecting young children and TTP being more common in middle-aged persons. Additionally, HUS is generally triggered by a diarrheal illness, which is much less common in TTP. On a molecular level, the metalloprotease ADAMTS13 specific for von Willebrand factor (vWF) is generally low if not absent in activity in TTP. The development of HUS is likely driven by bacterial toxins such as shiga toxin or shiga-like toxin, often from E. coli 0157:H7. Because TTP is associated with low protein levels that may be driven by autoantibodies, plasma exchange serves the dual purpose of removing the aberrant antibody and repleting protein levels. With appropriate therapy, 1-month mortality is approximately 20%. Untreated mortality nears 90%, primarily from microvascular thrombosis and multiorgan failure.
VII-30. The answer is C. (Chap. 286) Renal vein thrombosis occurs in 10–15% of patients with nephrotic syndrome accompanying membranous glomerulopathy and oncologic disease. The clinical manifestations can be variable but may be characterized by fever, lumbar tenderness, leukocytosis, and hematuria. Magnetic resonance venography is the most sensitive and specific noninvasive form of imaging to make the diagnosis of renal vein thrombosis. Ultrasound with Doppler is operator dependent and therefore may be less sensitive. Contrast venography is the gold standard for diagnosis, but it exposes the patient to a more invasive procedure and contrast load. Nuclear medicine screening is not performed to make this diagnosis.
VII-31. The answer is A. (Chap. 287) Calcium stones account for 75–85% of all kidney stones. Although they are most commonly caused by idiopathic hypercalciuria, hypocitraturia, hyperuricosuria, and primary hyperparathyroidism are also causes. Uric acid stones are the next most common stone, followed by cysteine and struvite. Oxalic acid does not form stones without complexing with a positive cation, such as calcium. Struvite stones are precipitated by bacterial infections, such as Proteus, that promote conversion of urea to ammonium and raise urinary pH. General management for calcium stones includes increasing consumption of water, low protein, and low calcium. If this is ineffective, thiazide diuretics may be used.
VII-32. The answer is D. (Chap. 289) Urinary tract obstruction is an important and potentially reversible cause of kidney failure. This patient is at risk for urinary obstruction based on her history of colon cancer. Although recent NSAID use may be contributing to the rapidity of her kidney damage, routine dosing is less likely to cause acute kidney injury in the absence of preexisting renal dysfunction. Ultrasound of the kidneys is the best screening test for obstruction. Hydroureter and/or hydronephrosis may be found and suggest the presence of obstruction. Although obstruction may be unilateral, it rarely causes clinically significant renal failure in the absence of underlying renal disease. CT of the abdomen is useful after ultrasound to evaluate the site and etiology of obstruction. Post-void residual is useful if functional causes of obstruction are suspected, such as urinary retention. After the obstruction site is located, retrograde urography with stent placement may be indicated, but only after defining the presence or absence of obstruction.
VII-33 and VII-34. The answers are E and D, respectively. (Chap. 289) The patient has relief of recent urinary obstruction and is now making an inappropriately large amount of urine. This is likely due to postobstructive diuresis, which results from release of obstruction, increase in GFR over the course of days, decreased tubule pressure, and increased solute load per nephron, resulting in increased urine output. Decreased medullary osmolarity is a feature of chronic obstruction and persistent obstruction. The patient has not had recent head trauma or neurosurgical procedure and is unlikely to have cerebral salt wasting. Increased activation of the renin-angiotensin-aldosterone system is associated with chronic, unrelieved obstruction. Patients with postobstructive diuresis are at risk for volume depletion with possible development of prerenal azotemia and resultant acute kidney injury, as well as electrolyte imbalance, particularly due to losses of Na, K, PO4, Mg, and free water. Erythrocytosis may be seen in
patients with obstruction, but is a rare feature and is not associated with postobstructive diuresis. Systemic hypotension is more common than hypertension due to volume depletion.
VII-35. The answer is C. (Chap. 289) In acute urinary tract obstruction, pain is due to distention of the collecting system or renal capsule. Acutely, there is a compensatory increase in renal blood flow when kidney function is impaired by obstruction, which further exacerbates capsular stretch. Eventually, vasodilatory prostaglandins act to preserve renal function when glomerular filtration rate has decreased. Medullary blood flow decreases as the pressure of the obstruction further inhibits the renal parenchyma from perfusing; however, the ensuing chronic renal destruction may occur without substantial pain. When an obstruction has been relieved, there is a postobstructive diuresis that is mediated by relief of tubular pressure, increased solute load (per nephron), and natriuretic factors. There can be an extreme amount of diuresis, but this is not painful.
VII-36. The answer is D. (Chap. 289) The level of obstruction is important when considering urinary tract obstruction. Bilateral hydronephrosis and hydroureter suggest either a systemic process or mechanical obstruction at or below the level of the uretero-vesical junctions. While retroperitoneal fibrosis can cause such a picture, it is most common among middle-aged men. In patients of reproductive age, genital tract infections can cause meatal stenosis if left untreated or if infections are recurrent. Retroperitoneal lymphomas can cause bilateral hydroureter, as can more distal obstructions like phimosis. In the developing world, one may also consider schistosomiasis and genitourinary tuberculosis.
SECTION VIII
Disorders of the Gastrointestinal System
QUESTION
DIRECTIONS: Choose the one best response to each question.
VIII-1. The advantages of endoscopy over barium radiography in the evaluation of dysphagia include all of the following EXCEPT:
A. Ability to intervene as well as diagnose
B. Ability to obtain biopsy specimens
C. Increased sensitivity for the detection of abnormalities identified by color, e.g., Barrett’s metaplasia
D. Increased sensitivity for the detection of mucosal lesions
E. No meaningful risk to procedure
VIII-2. A 47-year-old man is evaluated in the emergency department for chest pain that developed at a restaurant after swallowing a piece of steak. He reports intermittent episodes of meat getting stuck in his lower chest over the past 3 years, but none as severe as this event. He denies food regurgitation outside of these episodes or heartburn symptoms. He is able to swallow liquids without difficulty and has not had any weight loss. Which of the following is the most likely diagnosis?
A. Achalasia
B. Adenocarcinoma of the esophagus
C. Esophageal diverticula
D. Plummer-Vinson syndrome
E. Schatzki’s ring
VIII-3. Which of the following has a well-established association with gastroesophageal reflux?
A. Chronic sinusitis
B. Dental erosion
C. Pulmonary fibrosis
D. Recurrent aspiration pneumonia
E. Sleep apnea
VIII-4. A 36-year-old female with AIDS and a CD4 count of 35/mm3 presents with odynophagia and progressive dysphagia. The patient reports daily fevers and a 20-lb weight loss. She has been treated with clotrimazole troches without relief. On physical examination the patient is cachectic with a body mass index (BMI) of 16 and a weight of 86 lb. She has a temperature of 38.2°C (100.8°F) and is noted to be orthostatic by blood pressure and pulse. Examination of the oropharynx reveals no evidence of thrush. The patient undergoes esophagogastroduodenoscopy (EGD), which reveals serpiginous ulcers in
the distal esophagus without vesicles. No yellow plaques are noted. Multiple biopsies are taken that show intranuclear and intracytoplasmic inclusions in large endothelial cells and fibroblasts. What is the best treatment for this patient’s esophagitis?
A. Ganciclovir
B. Glucocorticoids
C. Fluconazole
D. Foscarnet
E. Thalidomide
VIII-5. A 57-year-old man is evaluated with an esophagogastroduodenoscopy after an episode of hematemesis. The patient reports a history of tobacco use and hypercholesterolemia, but is otherwise healthy. He has had lower back pain for the past month and has been intermittently using acetaminophen 1000 mg for relief. His endoscopy shows a 3-cm duodenal ulcer. Which of the following statements is correct regarding this finding?
A. The lesion should be biopsied as duodenal ulcers have an elevated risk of being due to carcinoma.
B. First-line therapy should be discontinuation of acetaminophen use.
C. The patient is not at risk for any associated cancers.
D. Poor socioeconomic status is a risk factor for development of this condition.
E. Antral gastritis is rarely found with this condition.
VIII-6. A 58-year-old man is evaluated for abdominal pain by his primary care physician. He reports severe stress at his job for the last 3 months and has since noted that he has epigastric pain that is relieved by eating and drinking milk. He has not had food regurgitation, dysphagia, or bloody emesis or bowel movements. He denies any symptoms in his chest. Peptic ulcer disease is suspected. Which of the following statements regarding noninvasive testing for Helicobacter pylori is true?
A. There is no reliable noninvasive method to detect H. pylori.
B. Stool antigen testing is appropriate for both diagnosis of and proof of cure after therapy for H. pylori.
C. Plasma antibodies to H. pylori offer the greatest sensitivity for diagnosis of infection.
D. Exposure to low-dose radiation is a limitation to the urea breath test.
E. False-negative testing using the urea breath test may occur with recent use of NSAIDs.
VIII-7. A 44-year-old woman complains of 6 months of epigastric pain that is worst between meals. She also reports symptoms of heartburn. The pain is typically relieved by over-the-counter antacid medications. She comes to the clinic after noting her stools darkening. She has no significant past medical history and takes no medications. Her physical examination is normal except for diffuse midepigastric pain. Her stools are heme positive. She undergoes EGD, which demonstrates a well-circumscribed 2-cm duodenal ulcer that is positive for H. pylori. Which of the following is recommended initial therapy given these findings?
A. Lansoprazole plus clarithromycin plus amoxicillin for 14 days
B. Pantoprazole plus amoxicillin for 21 days
C. Pantoprazole plus clarithromycin for 14 days
D. Omeprazole plus bismuth plus tetracycline plus metronidazole for 14 days
E. Omeprazole plus metronidazole plus clarithromycin for 7 days
VIII-8. A 57-year-old man with peptic ulcer disease experiences transient improvement with Helicobacter pylori eradication. However, 3 months later symptoms recur despite acid-suppressing therapy. He does not take nonsteroidal anti-inflammatory agents. Stool analysis for H. pylori antigen is negative. Upper GI endoscopy reveals prominent gastric folds together with the persistent ulceration in the duodenal bulb previously detected and the beginning of a new ulceration 4 cm proximal to the initial ulcer. Fasting gastrin levels are elevated and basal acid secretion is 15 meq/h. What is the best test to perform to make the diagnosis?
A. No additional testing is necessary.
B. Blood sampling for gastrin levels following a meal.
C. Blood sampling for gastrin levels following secretin administration.
D. Endoscopic ultrasonography of the pancreas.
E. Genetic testing for mutations in the MEN1 gene.
VIII-9. A 23-year-old woman is evaluated by her primary care physician for diffuse, crampy abdominal pain. She reports that she has had abdominal pain for the last several years, but it is getting worse and is now associated with intermittent diarrhea without flatulence. This does not waken her at night. Stools do not float and are not hard to flush. She has not noted any worsening with specific foods, but she does have occasional rashes on her lower legs. She has lost about 5 kg over the last year. She is otherwise healthy and takes no medications. Which of the following is the most appropriate recommendation at this point?
A. Increased dietary fiber intake
B. Measurement of antiendomysial antibody
C. Measurement of 24-hour fecal fat
D. Referral to gastroenterologist for endoscopy
E. Trial of lactose-free diet
VIII-10. All of the following are direct complications of short bowel syndrome EXCEPT:
A. Cholesterol gallstones
B. Coronary artery disease
C. Gastric acid hypersecretion
D. Renal calcium oxalate calculi
E. Steatorrhea
VIII-11. A 54-year-old man is evaluated by a gastroenterologist for diarrhea that has been present for approximately 1 month. He reports stools that float and are difficult to flush down the toilet; these can occur at any time of day or night, but seem worsened by fatty meals. In addition, he reports pain in many joints that lasts days to weeks and is not relieved by ibuprofen. His wife notes that the patient has had difficulty with memory for the last few months. He has lost 30 pounds and reports intermittent low-grade fevers. He takes no medications and is otherwise healthy. Endoscopy is recommended. Which of
the following is the most likely finding on small-bowel biopsy?