In adults, celiac disease manifests most commonly between 30 and 60 years of age. However, many cases escape clinical attention for extended periods because of atypical presentations. Some patients have silent celiac disease, defined as positive serology and villous atrophy without symptoms, or latent celiac disease, in which positive serology is accompanied neither by villous atrophy nor symptoms. Symptomatic adult celiac disease is often associated with anemia (due to iron deficiency and, less commonly, B12 and folate deficiency), diarrhea, bloating, and fatigue.
Fig. 15.22 Celiacdisease.(A)Advancedcasesofceliacdiseaseshowcom-pletelossofvilli,ortotalvillousatrophy.Notethedenseplasmacellinfil-tratesinthelaminapropria.(B)InfiltrationofthesurfaceepitheliumbyTlymphocytes,whichcanberecognizedbytheirdenselystainednuclei(labeledT).Comparewithelongated,pale-stainingepithelialnuclei(labeledE).
Noninvasive serologic tests are generally performed before biopsy. The most sensitive tests are the presence of IgA antibodies to tissue transglutaminase or IgA or IgG antibodies to deamidated gliadin. Anti-endomysial antibodies are highly specific but less sensitive than other antibodies.
Patients with celiac disease exhibit a higher than normal rate of malignancy. The most common celiac disease– associated cancer is enteropathy-associated T cell lymphoma, an aggressive tumor of intraepithelial T lymphocytes. Small-intestinal adenocarcinoma also is more frequent in individuals with celiac disease. Thus, when symptoms such as abdominal pain, diarrhea, and weight loss develop despite a strict gluten-free diet, cancer or refractory sprue, in which the response to a gluten-free diet is lost, must be considered. It is, however, important to recognize that failure to adhere to a gluten-free diet is the most common cause of recurrent symptoms, and that most individuals with celiac disease do well with dietary restrictions and die of unrelated causes.
The term environmental enteric dysfunction, or environmental enteropathy, refers to a syndrome of stunted growth and impaired intestinal function that is common in developing countries, including many parts of sub-Saharan Africa, such as Zambia; aboriginal populations within northern Australia; and some groups within South America and Asia, such as residents of impoverished communities within Brazil, Guatemala, India, and Pakistan. The impact of environmental enteric dysfunction, which was previously grouped under headings of tropical enteropathy or tropical sprue, cannot be overstated, as it is estimated to affect over 150 million children worldwide. Although malnutrition most likely contributes to the pathogenesis of this disorder, neither supplementary feeding nor vitamin and mineral supplementation are able to fully reverse the syndrome. Repeated bouts of diarrhea suffered within the first 2 or 3 years of life are most closely linked to environmental enteropathy, but no single infectious agent has been established as causal in these diarrheal episodes. Intestinal biopsy specimens have been examined in only a small number of cases, and the reported histopathology has some overlap with severe celiac disease as well as infectious enteritis.
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Lactase deficiency gives rise to osmotic diarrhea because, in its absence, osmotically active lactose remains in the lumen. The disaccharidases, including lactase, are located in the apical brush border membrane of villous absorptive epithelial cells. Because the defect is biochemical, biopsies are generally unremarkable. Lactase deficiency is of two types: