Abstract
Malabsorptive symptoms can be caused by a variety of medications and immune-mediated, infectious, and genetic disorders that share a final common pathway resulting in decreased small-intestinal surface area. Many immune-mediated and medication-related conditions cause a malabsorptive histologic pattern of injury characterized by villous blunting, intraepithelial lymphocytosis, and mononuclear cell-rich inflammation in the lamina propria. Others features include prominent epithelial cell injury, crypt cell apoptosis, and crypt destruction. Correct classification of these disorders requires knowledge of their distinctive histologic features, presenting symptoms and medical history, serologic studies, distribution of disease, and endoscopic findings. The purpose of this chapter is to address frequently asked questions that arise when evaluating biopsy or resection samples from patients with clinical features of intestinal malabsorption and offer suggestions regarding the pathologic reporting of these cases.