title: Pleural effusion in women with a known adenocarcinoma: the role of immunostains in uncovering another hidden primary tumor.
abstract: OBJECTIVE
  Pleural fluid metastasis occurs often secondary to a known primary tumor. We aim to identify the percentage of adenocarcinomas metastatic to pleural effusion in women and the frequency of another primary tumor being the origin of the effusion using morphology and immunostains.
  
  
  METHODS
  One hundred and thirty-one cases from our archives were reviewed.
  
  
  RESULTS
  Ninety-four percent had a documented primary. The breast was the most common site (34%); less common were the lung and ovary, and 7.9% had two different primaries. Seven cases proved to be secondary to an adenocarcinoma other than the one on record. Lung tumors were the most common overlooked tumors (5/7 cases). Six percent remained of inconclusive origin due to an occult primary, absent cells on cell blocks, or discordance with radiology or cytology of a known primary. Morphology in association with a small panel of immunostains including thyroid transcription factor 1, estrogen receptor, mammaglobin, Wilms tumor antigen 1, CA125 and CDX2 proved helpful in identifying the primary origin in 94% of cases.
  
  
  CONCLUSIONS
  After a morphological comparison with previously available material, and due to major implications in the therapeutic strategy, a small panel of immunostains is advised on available cell block material to verify the origin of the metastatic effusion.
authors: Department of Cytology, William Beaumont Hospital, Royal Oak, MI, USA. samnasser78@gmail.com
authors: H
authors: H
authors: Nasser
authors: T J
authors: TJ
authors: Kuntzman
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology / Q000556:secondary*; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008875:Middle Aged; D009369:Neoplasms / Q000276:immunology / Q000473:pathology*; D010996:Pleural Effusion / Q000276:immunology / Q000473:pathology*