title: Does Hepatocyte Paraffin 1 expression stand a role in determining the site origin of an adenocarcinoma from unknown gastrointestinal primary?
abstract: BACKGROUND
  Hepatocyte Paraffin 1 (Hep Par 1) was being extensively used to recognize the hepatocellular carcinomas, until recognition of its expression in tumors without hepatocellular differentiation.
  
  
  OBJECTIVE
  The aim of this study was to analyze if Hep Par 1 stain can serve as a specific marker of the small intestinal (SI) adenocarcinomas, versus other gastrointestinal tract (GIT) primary tumors.
  
  
  METHODS
  In this retrospective cross-sectional study, normal GIT mucosa (n - 60), corresponding adenocarcinomas (n - 60) and nodal metastatic foci (n - 60) from the same patients, including 10 cases each from the esophagus, stomach, SI periampullary region, colon, rectum, and gall bladder were included. H-score was calculated by multiplying the stain distribution and intensity scores. The H-scores were compared with other clinical and histological parameters.
  
  
  RESULTS
  While normal SI mucosa showed diffuse strong Hep Par 1 staining, normal esophageal and gastric epitheliums were negative and normal colon, rectal, and biliary epithelium showed weak focal positivity. Adenocarcinomas from all these sites, however, showed Hep Par 1 expression, irrespective of the tumor type, site or origin, and tumor stage. The corresponding metastatic sites also showed variable Hep Par 1 positivity, without any site specificity.
  
  
  CONCLUSIONS
  Hep Par 1 stain cannot help to determine the exact site of origin of primary GIT tumors. Its expression in adenocarcinomas across the GIT and their metastatic foci proves that it cannot be regarded as a marker of SI differentiation, especially in malignancy.
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rajni
authors.initials: R
authors.lastname: Yadav
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Saurav
authors.initials: S
authors.lastname: Chopra
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Aayushi
authors.initials: A
authors.lastname: Garg
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Brijnandan
authors.initials: B
authors.lastname: Gupta
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Prateek
authors.initials: P
authors.lastname: Kinra
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Siddhartha Datta
authors.initials: SD
authors.lastname: Gupta
authors.affiliation: Department of Pathology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Prasenjit
authors.initials: P
authors.lastname: Das
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D006651:Histocytochemistry / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D010338:Pathology, Clinical / Q000379:methods*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; C000600022:HepPar-1 protein, human