Immunodeficiency Disorders Resulting in Malabsorption.

Gastrointestinal (GI) disorders are present in 5–50 % of patients with primary immunodeficiencies. These manifestations mimic classic forms of disease (in the absence of immunodeficiency) such as celiac disease, food allergy, or inflammatory bowel disease, but they are often unresponsive to conventional therapies. Because GI disease may be the first presentation of an underlying immunodeficiency, it is crucial to consider immunodeficiency in any child with recurrent or chronic severe diarrhea, malabsorption, and failure to thrive resistant to conventional treatments. At the same time, routine evaluation of GI tract is useful for children with immunodeficiency, given the high incidence of GI disorders in these patients and considering that early evaluation and diagnosis can prevent potentially irreversible tissue damage. Primary immunodeficiencies are relatively common but likely underdiagnosed. A clinical history of recurrent, opportunistic, or unusual infections; histological features that do not fit the usual pattern of disease; and a poor response to conventional therapy should prompt the pediatrician to pursue further immunologic evaluation in collaboration with the immunologist.