title: Utility of TTF-1 and Napsin-A in the work-up of malignant effusions.
abstract: BACKGROUND
  Similar to TTF-1, Napsin-A is recently used increasingly to differentiate between pulmonary adenocarcinoma (P-ADC) and extra-pulmonary adenocarcinoma (EP-ADC). The aim of this study was to compare the performance of TTF-1 and Napsin-A in determining the primary origin of adenocarcinoma in malignant serous effusion.
  
  
  METHODS
  Following IRB approval, cellblocks from 139 cases of malignant serous effusions of histologically or clinically determined origin including: 26 P-ADC, 108 EP-ADC, 2 pulmonary squamous cell carcinoma (P-SQC), and 3 pulmonary small cell carcinoma (P-SCC) were retrieved. Each case was stained with Napsin-A and TTF-1 and evaluated for positivity and intensity of staining.
  
  
  RESULTS
  Napsin-A and TTF-1 stained positive in 17/26 (65%) and 14/26 (54%) of P-ADC and in 2/108 (1.8%) and 0/108 (0%) of EP-ADC with a PPV of 89 and 100%, respectively. In combination, they positively stained 18/26 (70%) of P-ADC with a PPV of 90%. Out of 9 poorly differentiated P-ADC, 7 (78%) stained positive for Napsin-A, while 4 (45%) were reactive for TTF-1. Both Napsin-A and TTF-1 were negative in P-SQC, while P-SCC reacted positively for TTF-1 in 2/3 (66%) of cases and none for Napsin-A.
  
  
  CONCLUSIONS
  Napsin-A and TTF-1 are both useful markers in distinguishing P-ADC from EP-ADC. However, Napsin-A performed better in poorly differentiated P-ADC and its mimickers. The nuclear staining of TTF-1 is crispier and much easier to interpret than Napsin-A cytoplasmic stain. An antibody panel including TTF-1 and Napsin-A or a dual stain will be very helpful in determining the origin of metastatic adenocarcinoma in serous effusion.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota Medical Center, 420 Delaware St SE, Minneapolis, Minnesota.
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Hag
authors.affiliation: Department of Pathology, Marshfield Clinic, 3401 Cranberry Blvd, Weston, Wisconsin.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Schmidt
authors.affiliation: University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, Michigan.
authors.forename: Michael
authors.initials: M
authors.lastname: Roh
authors.affiliation: University Hospitals Case Medical Center, Case Western Reserve University, 11100 Euclid Ave, Rm 212B, Cleveland, Ohio.
authors.forename: Claire W
authors.initials: CW
authors.lastname: Michael
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D000077192:Adenocarcinoma of Lung; D016282:Aspartic Acid Endopeptidases / Q000235:genetics*; D014408:Biomarkers, Tumor / Q000235:genetics*; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D004268:DNA-Binding Proteins / Q000235:genetics*; D003937:Diagnosis, Differential; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D016066:Pleural Effusion, Malignant / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D012680:Sensitivity and Specificity; D016610:Tissue Embedding; D014157:Transcription Factors
chemical_list: D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; C504003:TTF1 protein, human; D014157:Transcription Factors; D016282:Aspartic Acid Endopeptidases; C498549:NAPSA protein, human
keywords: Napsin-A; TTF-1; adenocarcinoma; lung; malignant effusion; serous effusion