HISTOPATHOLOGICAL DIAGNOSIS OF INTRAHEPATIC AND EXTRAHEPATIC NEONATALCHOLESTASIS

The histopathology of the liver is fundamental for the differential di agnosis between intra-and extrahepatic causes of neonatal cholestasis. However, histopathological findings may overlap and there is disagree ment among authors concerning those which could discriminate between i ntra-and extrahepatic cholestasis. Forty-six liver biopsies (35 wedge biopsies and 11 percutaneous biopsies) and one specimen from a postmor tem examination, all from patients hospitalized for neonatal cholestas is in the Pediatrics Service of Hospital de Clinicas de Porto Alegre, were prospectively studied using a specially designed histopathologica l protocol. At least 4 of 5 different stains were used, and 46 hepatic histopathological variables related to the differential diagnosis of neonatal cholestasis were studied. The findings were scored for severi ty on a scale from 0 to 4. Sections which showed less than 3 portal sp aces were excluded from the study. Sections were examined by a patholo gist who was unaware of the final diagnosis of each case. Bile tract p ermeability was defined by scintigraphy of the bile ducts and operativ e cholangiography. The F test and discriminant analysis were used as s tatistical methods for the study of the hepatic histopathological vari ables. The chi-square method with Yates correction was used to relate the age of the patients on the date of the histopathological study to the discriminatory variables between intra- and extrahepatic cholestas is selected by the discriminant function test. The most valuable hepat ic histopathological variables for the discrimination between intra-an d extrahepatic cholestasis, in decreasing order of importance, were pe riportal ductal proliferation, portal ductal proliferation, portal exp ansion, cholestasis in neoductules, foci of myeloid metaplasia, and po rtal-portal bridges. The only variable which pointed to the diagnosis of intrahepatic cholestasis was myeloid metaplasia. Due to the small n umber of patients who were younger than 60 days on the date of the his topathological study (N = 6), no variable discriminated between intra- and extrahepatic cholestasis before the age of 2 months and all of the m, except for the portal expansion, were discriminatory after this age . In infants with cholestasis, foci of myeloid metaplasia, whenever pr esent in the liver biopsy, suggested intrahepatic cholestasis. Peripor tal ductal proliferation, portal ductal proliferation, portal expansio n, cholestasis in neoductules, portal cholestasis and portal-portal br idges suggested extrahepatic obstructive cholestasis.