title: Cytologic Features and Immunocytochemical Profiles of Malignant Effusions with Metastatic Papillary Thyroid Carcinoma: A Case Series from a Single Institution.
abstract: OBJECTIVE
  Malignant effusions due to papillary thyroid carcinoma (PTC) are rare, but portend a poor prognosis. PTC metastases, although rare, most frequently occur in the lungs and bone. Therefore, differentiating thyroid etiology of malignant effusions from other sites becomes clinically significant in patient management. This study examines morphologic and immunocytochemical findings in 5 cases of malignant effusions with PTC involvement.
  
  
  METHODS
  The electronic database at the University of Michigan was searched from January 1, 1995 to December 31, 2014 for malignant pleural effusions with PTC involvement. Clinicopathologic data were obtained from electronic medical records. Cytologic slides were reviewed.
  
  
  RESULTS
  Five cases of malignant effusions due to PTC were identified. Characteristic cytologic features of PTC, including ovoid nuclei, irregular nuclear contours, and psammomatous calcifications, were seen. However, the predominant cytologic feature observed was moderate amounts of delicate to vacuolated cytoplasm within the tumor cells. A review of immunocytochemistry demonstrated that all 5 cases showed patchy to diffuse TTF-1 positivity and diffuse positivity for Pax-8. Thyroglobulin only showed focal to patchy positivity in 3 of 5 cases.
  
  
  CONCLUSIONS
  Given the morphologic features found in our case series, an immunocytochemical workup for the evaluation of involvement of an effusion by a thyroid primary is crucial for accurate diagnosis and appropriate clinical treatment.
authors.affiliation: Department of Pathology, University of Michigan Health System, Ann Arbor, Mich., USA.
authors.forename: Madelyn
authors.initials: M
authors.lastname: Lew
authors.forename: Judy C
authors.initials: JC
authors.lastname: Pang
authors.forename: Michael H
authors.initials: MH
authors.lastname: Roh
authors.forename: Xin
authors.initials: X
authors.lastname: Jing
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D001706:Biopsy; D002277:Carcinoma / Q000737:chemistry* / Q000556:secondary* / Q000601:surgery; D002291:Carcinoma, Papillary; D016208:Databases, Factual; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008824:Michigan; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000032:analysis; D016066:Pleural Effusion, Malignant / Q000737:chemistry* / Q000473:pathology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000032:analysis; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000737:chemistry* / Q000473:pathology* / Q000601:surgery; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000032:analysis
chemical_list: D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000072636:PAX8 Transcription Factor; C083325:PAX8 protein, human; D051761:Paired Box Transcription Factors; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D013954:Thyroglobulin