Diagnostic Challenges in Enteropathies: A Histopathological Review.

Various enteropathies, including immune-mediated (IME) and infection-related conditions, can lead to small intestinal mucosal injury and malabsorption. While immune dysregulation plays a central role in diseases like celiac disease and autoimmune enteropathy, other conditions such as small intestinal bacterial overgrowth (SIBO) and tropical sprue (TS) involve infectious or microbial pathogenesis. Common clinical manifestations include weight loss, chronic diarrhea, and nutritional deficiencies. While celiac disease (CD) remains the most prevalent IME in adults, an expanding spectrum of non-celiac enteropathies has been recognized, including autoimmune enteropathy (AIE), common variable immunodeficiency disease (CVID), olmesartan-induced enteropathy, tropical sprue, and small intestinal bacterial overgrowth. These conditions often present with overlapping clinical, serological, and histological features, complicating their differentiation from CD. Accurate diagnosis is critical for the timely initiation of effective treatment to prevent disease progression and associated complications such as severe malabsorption and enteropathy-associated T-cell lymphoma (EATL). The small intestine plays a dual role in nutrient absorption and immune regulation, making it uniquely vulnerable to immune dysregulation. In IMEs, hyperactive immune responses disrupt intestinal homeostasis, leading to mucosal damage and impaired nutrient absorption. Although CD is the prototypical IME, increasing the recognition of non-celiac IMEs, it highlights the need for a more nuanced approach to small bowel biopsy interpretation. This review explores the histopathological and clinical features of common IMEs, with a focus on distinguishing non-celiac disorders that mimic CD. By enhancing the understanding of these conditions, this review aims to improve diagnostic accuracy, facilitate appropriate therapeutic interventions, and mitigate complications associated with delayed or misdiagnosis. A multidisciplinary approach involving gastroenterologists and pathologists is emphasized to optimize outcomes for patients with IMEs. Immune-mediated enteropathies result from an abnormal immune response of the small intestinal mucosa to non-pathogenic molecules, often leading to malabsorption syndrome. The most common symptoms include weight loss, chronic diarrhea, and nutritional deficiencies. While celiac disease (CD) is the most well-known immune-mediated enteropathy (IME) in adults, other related disorders have been identified in recent years. These conditions share many clinical and histopathological features, therefore making differentiations between them challenging. This study aims to review the most common immune-mediated enteropathies, with a focus on non-celiac disorders that should be considered in the differential diagnosis of celiac disease in small bowel biopsies.