Strongyloides stercoralis eosinophilic granulomatous enterocolitis

Six patients suffering from an unusual form of colitis produced by Strongyloides stercoralis hyperinfection are described. In contrast to the usual Strongyloides hyperinfection syndrome, in which small intestinal and pulmonary manifestations are seen in patients with some forms of immunodeficiency, the patients described here presented with only a characteristic transmural eosinophilic granulomatous inflammation affecting mostly the colonic wall and clinically mimicking ulcerative colitis or Crohn's disease. This Strongyloides eosinophilic granulomatous enterocolitis apparently results from a florid inflammatory response by eosinophils, histiocytes, and giant cells with formation of granulomas that destroy the larvae entering the colon. This morphologic picture differs from that of the well-described hyperinfection syndrome, in which the bulk of the larvae pass through the colonic wall to complete the life cycle, with only a few larvae destroyed in the colon. The probable pathophysiologic mechanism of this unusual manifestation of hyperinfection is discussed based on the anatomic and clinical observations of patients who presented at different stages in the evolution of their condition and whose length of follow-up varied.