By Craig E. Litz, M.D.
A 74-year-old female presented to her physician with a several month history of watery diarrhea and intermittent mild crampy abdominal pain. Her physical exam was normal. The colon appeared endoscopically normal with the exception of a small incidental polyp of the sigmoid colon. Random biopsies and polypectomy were performed.
Microscopically, the random biopsies showed a marked lymphocytic exostosis (>2 lymphocytes/10 enterocytes) of the superficial and crypt epithelium with evidence of surface epithelial damage, increased numbers of lymphocytes and plasma cells of the lamina propria, intact glandular architecture, and absence of a thickened basement membrane (figure 1 and figure 2, top panel). Immunohistochemically, the lymphocytes were T-cytotoxic cells (CD3+, CD8+; figure 2, lower panel). The microscopic findings were diagnostic of lymphocytic colitis; an incidental hyperplastic polyp was also diagnosed.
Lymphocytic colitis together with collagenous colitis represent the “microscopic colitides” because they are defined by microscopic abnormalities alone. The two entities share several clinical and histologic features and are considered closely related. Patients are predominantly female, between 40-70 years old, and typically present with a long-standing history of watery, non-bloody diarrhea. Other symptoms frequently include colicky abdominal pain, fecal incontinence at night, and mild weight loss. Exacerbations and remissions characterize these disorders. Microscopically, lymphocytic and collagenous colitis both show conspicuous T-cytotoxic mediated damage of the gut epithelium with collagenous colitis distinguished by the presence of a markedly thickened superficial basement membrane. Disordered glandular architecture, acute cryptitis and crypt abscesses typical of inflammatory bowel disease are not present. An association of the microscopic colitides with the regular ingestion of nonsteroidal anti-inflammatory drugs, autoimmune diseases, and celiac disease has been proposed. Collagenous colitis frequently responds to anti-inflammatory medications.
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