Systemic diseases affecting the GI tract: A review of clinical and histopathologic manifestations

A variety of systemic diseases may affect the gastrointestinal (GI) tract. Since the GI tract responds to injury in limited ways, identifying these processes may be challenging, especially on small endoscopic biopsies. This article reviews the clinicopathologic features of commonly encountered systemic diseases affecting the tubular GI tract: sarcoidosis, graft vs. host disease, mast cell disorders, systemic sclerosis, and IgG-4 related disease. In addition, we offer guidance in differentiating them from their mimics.