Utility of TTF‐1 and Napsin‐A in the work‐up of malignant effusions. Issue 4 (22nd January 2016)

• Record Type: Journal Article
• Authors: El Hag, Mohamed; Schmidt, Lindsay; Roh, Michael; Michael, Claire W.
• Is Part Of: Diagnostic cytopathology. Volume 44:Issue 4(2016)
• Page Start: 299
• Page End: 304
• Publication Date: 2016-01-22
• Subjects: malignant effusion -- serous effusion -- adenocarcinoma -- lung -- TTF‐1 -- Napsin‐A; Cytodiagnosis -- Periodicals; Pathology, Cellular -- Periodicals; Cytology -- Periodicals; 616.07582
• DOI: 10.1002/dc.23442
• Languages: English
• ISSNs: 8755-1039

Abstract

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. Conclusion: 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. Diagn. Cytopathol. 2016;44:299–304. © 2016 Wiley Periodicals, Inc.