Hepatitis B surface antigen and chronic liver disease in Tanzania: Aa histochemical study for demonstrating hepatitis B antigen in liver sections using orcein staining technique.

Chronic liver diseases including cirrhosis and heoatoma are found in a much higher frequency in tropical Africa and Asia than in temperate countries, but their aetiology is unknown and has remained largely speculative. Hepatitis B surface antigenaemia (HBsAg) is also encountered at a significantly higher rate in these tropical settings and it has been suggested that thronic liver diseases and HBsAg could be aetiologically associated. In fact many studies have conformed a higher incidence rate of HBsAg in the sera of patients with chronic active hepatitis, postnecrotic –posthepatitic cirrhosis and hepatoma than in suitable controls or patients with other chronic liver injury. At present it is possible to demonstrate, (using electron microscopy and immunofluorescence) HBsAg in hepatocytes, the presumed site of HBsAg formation. These methods are complicated and not widely available. Recently a simple histochemical method using ORCEIN stain has been developed to stain HBsAg material in liver sections. The positive stains have been shown to correlate closely with the antigen as demonstrated by electron microscopy and immunifluorescence. The mechanism of the stain is thought to be due to the high affinity disulphide bonds have for orcein, for HBsAg is rich in these bonds. The study was designed so as to demonstrate HBsAg, using orcein staining technique, in liver sections of various histological diagnosis. 75 paraffin-embedded consecutive liver specimens which had been received by the central pathology laboratory Dar es Salaam were included in the study. Their histological diagnosis were initially not known. 41 of the specimen came from inpatients who in addition had alpha fetoprotein, serum HBsAg and liver function tests done on them. The remaining (34) were from the laboratory collection. In the final analysis 66 specimen were available. Positive orcein staining was demonstrated in specimens as follows:- acute viral hepatitis 2 of 6 specimen (33%); chronic active hepatitis 3 of 5 (60%) postnecrotic cirrhosis 10 of 18 (56%); hepatoma 7 of 14 (50%) specimens, and in one specimen with secondary deposits from the gut. Negative orcein staining was found in haemosiderosis (2), haemosiderosis with cirrhosis (10), Tropical splenomegally syndrome (2), Tuberculous granulomata of the liver (1) and 6 normal livers. The presumed pathogenetic sequence of hapatoma following viral infection is acute viral hepatitis, chronic active hepatitis, postnecrotic cirrhosis and hepatoma. In this study 43 specimens fell in one or the other of these diagnostic categories and 22 (51%) of them were orcein positive. It is concluded that HBsAg may have an important role to play in hepato-carcinogenesis in Tanzania. (The manuscript is preceded by a review of literature pertaining to HBsAg).