A 46-year-old man comes to the office due to abdominal discomfort and diarrhea. The symptoms began 6 months ago, and he has now developed significant weight loss. The patient does not use tobacco or alcohol. Intestinal biopsy is performed, and a periodic acid-Schiff (PAS) stained section is shown in the image below: Which of the following is the most likely cause of this patient's symptoms?

Question

A 46-year-old man comes to the office due to abdominal discomfort and diarrhea.  The symptoms began 6 months ago, and he has now developed significant weight loss.  The patient does not use tobacco or alcohol.  Intestinal biopsy is performed, and a periodic acid-Schiff (PAS) stained section is shown in the image below:  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

This patient with abdominal pain and malabsorption has intestinal biopsy findings consistent with Whipple disease, a rare, systemic, chronic bacterial infection that most commonly presents in middle-aged men (age 40-60). It is caused by Tropheryma whipplei, a gram-positive, rod-shaped actinomycete. Following ingestion, the bacteria are engulfed by macrophages in the small intestine mucosa. T whipplei interferes with phagolysosome development and antigen presentation, allowing the organism to replicate within macrophages with minimal inflammatory response. Buildup of infected macrophages can block lymphatic channels, leading to malabsorption (eg, diarrhea, steatorrhea, weight loss, abdominal pain). T whipplei can also spread to the joints, causing arthralgia. In later stages of the disease, the infection can involve the central nervous system (eg, dementia) and heart (eg, endocarditis). Diagnosis can be confirmed with biopsy of the small intestine. Microscopic examination of the lamina propria shows numerous foamy macrophages distended by bacilli that are characteristically positive for periodic acid-Schiff (PAS) stain. PAS stains polysaccharides in the T whipplei membrane, imparting a magenta color. (Choice B) Celiac disease, an immune-mediated hypersensitivity to dietary gluten, can present with abdominal pain, diarrhea, and weight loss. However, biopsy of the small intestine would likely show villous atrophy, increased intraepithelial lymphocytes, and crypt hyperplasia. (Choice C) Abetalipoproteinemia is caused by an inherited defect in formation of apolipoprotein B-containing lipoproteins. This results in impaired lipid transport, leading to fat accumulation within enterocytes. Although malabsorptive symptoms are seen, this disease presents during the first year of life, and intestinal biopsy shows enterocytes with clear cytoplasmic lipid vacuoles. (Choice D) Lactase deficiency can cause abdominal pain and diarrhea following dairy consumption. However, microscopic examination of the small intestine typically shows no abnormalities. (Choice E) Although viral gastroenteritis (eg, norovirus) often presents with abdominal pain and diarrhea, symptoms typically resolve within a week in immunocompetent patients. Intestinal biopsy may show inflammation in the lamina propria, but PAS-positive macrophages would not be expected. Educational objective: Whipple disease is caused by a chronic infection with Tropheryma whipplei, a gram-positive bacterium that can affect multiple organ systems. It typically presents in middle-aged men with malabsorption and arthralgia. Intestinal biopsy characteristically shows foamy macrophages in the lamina propria filled with bacilli that are positive for periodic acid-Schiff stain. __________ References: Clinical manifestations, treatment, and diagnosis of Tropheryma whipplei infections. (http://www.ncbi.nlm.nih.gov/pubmed/28298472)

A 46-Year-Old Man Comes to the Office Due to Abdominal