A 38-year-old woman comes to the office due to intermittent abdominal pain and bloating since childhood. The patient does not drink milk because she does not like the taste and adds, "I eat ice cream, cheese, and yogurt, but they upset my stomach sometimes." There is no associated weight loss, abnormal bleeding, or joint pain. Past medical history is otherwise unremarkable, though the patient has not seen a physician for many years. Vital signs and physical examination are normal. Laboratory studies show normal hemoglobin, iron, and vitamin D levels. A biopsy sample of this patient's small bowel mucosa would most likely show which of the following?

Question

A 38-year-old woman comes to the office due to intermittent abdominal pain and bloating since childhood.  The patient does not drink milk because she does not like the taste and adds, "I eat ice cream, cheese, and yogurt, but they upset my stomach sometimes."  There is no associated weight loss, abnormal bleeding, or joint pain.  Past medical history is otherwise unremarkable, though the patient has not seen a physician for many years.  Vital signs and physical examination are normal.  Laboratory studies show normal hemoglobin, iron, and vitamin D levels.  A biopsy sample of this patient's small bowel mucosa would most likely show which of the following?

Quizplus · Accepted Answer

This patient, with gastrointestinal distress caused by consumption of lactose-containing dairy products, has typical features of lactase deficiency. Lactase deficiency results in incomplete hydrolysis of the disaccharide lactose into glucose and galactose. Undigested lactose in the bowel attracts excess water into the bowel lumen, leading to osmotic diarrhea. However, light and electron microscopic examinations show normal bowel mucosa in patients with primary lactase deficiency. Primary lactase deficiency can be classified as congenital or acquired. The congenital variant is a rare autosomal recessive condition that presents with diarrhea after birth. The acquired variant is more common and typically arises from decreased production of lactase by mid childhood (lactase nonpersistence). (Choices A and E) Secondary lactase deficiency is seen in disorders that cause injury to the gastrointestinal mucosa. Celiac disease is characterized by atrophy of the intestinal villi and is due to exposure to gluten-containing wheat products. Crohn disease causes noncaseating granulomas, and usually presents with abdominal pain and a variety of other gastrointestinal symptoms. Lactase deficiency due to these conditions is usually seen in association with other features of malabsorption (eg, iron deficiency, vitamin D deficiency). (Choice B) Diffuse inflammatory infiltrates with neutrophilic microabscesses in the crypt lumina can be seen in patients with ulcerative colitis, which usually presents with intermittent bloody diarrhea and abdominal pain. (Choice C) Distended macrophages in the intestinal lamina propria are a typical finding in Whipple disease, which characteristically presents with malabsorptive diarrhea, weight loss, and joint pain. (Choice D) Infiltration of the lamina propria with atypical lymphocytes would be expected in patients with gastrointestinal MALT (mucosa-associated lymphoid tissue) lymphomas. These often occur in the setting of chronic immune stimulation (eg, gastric MALT lymphoma with chronic Helicobacter pylori infection). Educational objective: The small bowel mucosa of patients with primary lactase deficiency is normal on histologic examination.

A 38-Year-Old Woman Comes to the Office Due to Intermittent