title: Immunohistochemical evaluation of inhibin-alpha in non-small-cell lung carcinomas--a pitfall in diagnosing metastatic pulmonary carcinomas.
abstract: BACKGROUND
  Inhibin-alpha is commonly used in differentiating non-small-cell lung carcinoma from certain metastatic carcinomas, but a study on a large series of primary lung cancer cases has not yet been published.
  
  
  OBJECTIVE
  To establish whether non-small-cell lung carcinoma can express inhibin-alpha; if so, caution should be exercised when using the molecule to evaluate metastatic lung cancer in both lung and extrapulmonary sites.
  
  
  METHODS
  187 cases of non-small-cell lung carcinoma and small-cell lung carcinoma were evaluated for expression of inhibin-alpha on both routine and tissue microarray sections by immunohistochemistry. These cases included 90 mixed or acinar adenocarcinomas, 2 acinar carcinomas with mucinous feature, 6 bronchioloalveolar carcinomas, 9 large-cell carcinomas, 2 adenosquamous carcinomas, 2 sarcomatoid carcinomas, 41 squamous cell carcinomas, 12 typical carcinoid tumors, 3 atypical carcinoid tumors, 20 small-cell lung carcinomas, and 19 cases of normal lung. The staining intensity was graded as weak, intermediate, or strong. The distribution was recorded as negative (no staining), 1+ (<25%), 2+ (26-50%), 3+ (51-75%), or 4+ (>75%). Cytoplasmic coarse granular staining for inhibin-alpha was the indicator for a positive result.
  
  
  RESULTS
  A subset of primary mixed or acinar and mucin-producing acinar carcinomas (10%) and large-cell carcinomas (22%) expressed inhibin-alpha. No expression of inhibin alpha was observed in the remaining cancers or normal lung samples.
  
  
  CONCLUSIONS
  Since a significant percentage of non-small-cell lung carcinoma cases expressed inhibin-alpha, caution should be taken when using inhibin-alpha as the key antibody for exclusion of a lung primary in lung and other organs.
authors.affiliation: Geisinger Medical Laboratory, Geisinger Medical Center, Danville, PA 17822, USA. kzhang1@geisinger.edu
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.forename: Jianhui
authors.initials: J
authors.lastname: Shi
authors.forename: Fan
authors.initials: F
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007265:Inhibins / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000175:diagnosis*
chemical_list: C094377:inhibin-alpha subunit; D007265:Inhibins