Pathological lesions associated with schistosoma mansoni infection in man

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Abstract
The pathological lesions associated with schistosome infection in Bahia, Brazil, were reviewed in an attempt to clarify the nature and prevalence of the lesions caused by S. mansoni, and to define better our material for comparison with that from other centres. The prevalence of various lesions possibly caused by schistosome infection was determined in cadavers with and without S. mansoni infection. The records of 1435 consecutive autopsies were reviewed, 502 of which showed the infection. In 105 of these, Symmers''s clay-pipe-stem fibrosis of the liver was present. All cases of portal hypertension attributed to schistosomiasis had Symmer''s fibrosis, and nearly all cases of Symmer''s fibrosis had symptoms and signs of marked portal hypertension. Schistosomal pulmonary arteritis and cor pulmonale were frequent in cases of Symmers''s fibrosis, but in those without Symmers''s fibrosis no unequivocal cases of cor pulmonale caused by schistosomiasis were identified. Another positive finding was segmen-tal fibrous thickening of the colonic serosa and of the mesocolon, lesions most frequently seen in cases with Symmers''s fibrosis. Fibrosis of the intestinal submucosa was rare. The absence of severe or diffuse fibrosis of the intestinal submucosa and the decreasing incidence of infection with increasing age in cases diagnosed by tissue examination, indicate that increased egg retention with decreased excretion of eggs in the feces is, by itself, an unlikely explanation for decreased egg excretion noted in older persons. Death of worms or a decrease in egg production are hypotheses more consistent with the present observations. A number of other lesions showed no positive correlation with schistosome infection. These included cirrhosis, hepatoma, ulcerative intestinal lesions and clinically significant colonic polyposis. Thus Symmers''s fibrosis was the most significant lesion caused by schistosome infection in our material, and nearly all other serious lesions related to schisotosome infection were found almost exclusively in the cases also having Symmers''s fibrosis. Compared with subjects with cirrhosis, more of those with Symmers''s fibrosis died from rupture of oesophago-gastric varices and showed lower indices of hepatic coma, jaundice, oedema and ascites. Liver and spleen sizes were larger in subjects with Symmers''s fibrosis than in those with cirrhosis. Portal vein thrombosis was more frequent in cases with Symmers''s fibrosis, and was very frequent in patients who had been subjected to surgery.