Hepatic immunohistochemistry of bile transporters in progressive familial intrahepatic cholestasis.

UNLABELLED  Background. Diagnosis of progressive familial intrahepatic cholestasis (PFIC) is a challenging matter that involves the summation of clinical, laboratory, radiological, and liver histological parameters; in addition to specific investigations to exclude other causes of neonatal cholestasis. The aim of this study was to evaluate liver tissue immunohistochemistry of bile salt export pump (BSEP) and multidrug resistance 3 (MDR3) proteins in differentiating PFIC from other causes of neonatal cholestasis, particularly, when genotyping is unavailable. MATERIAL AND METHODS The study included 25 patients diagnosed phenotypically as PFIC including 2 with PFIC1, 17 with PFIC2 and 6 with PFIC3. A second group of 25 cholestatic newborns with confirmed etiologies other than PFIC, termed as non-PFIC, included as controls. Liver biopsies from all patients were obtained and immunostained for BSEP and MDR3. RESULTS Negative immunoreaction of BSEP and MDR3 was found in the majority of PFIC group (76 and 64% respectively). Nonetheless, the negative immunoreaction was demonstrated in a considerable number of the non-PFIC group. BSEP immunoreaction was negative in the majority (82.4%) of PFIC2 but in none of the two patients with PFIC1. In addition, negative MDR3 immunoreaction was more frequently associated with PFIC3 compared to non-PFIC group. CONCLUSION MDR3 and BSEP immunostaining would be a helpful tool in supporting the phenotypic diagnosis of PFIC subtypes and in differentiating PFIC from other causes of neonatal cholestasis.