The development of targeted therapy has led to the need for subtyping of non-small cell lung carcinomas (NSCLC). The aim of this study was to assess the utility of immunohistochemical (IHC) markers in subtyping particularly poorly differentiated NSCLC in small biopsy specimens and also investigate NSCLC for enteric differentiation.
A total of 760 small lung biopsies diagnosed as NSCLC between 2001-2011 were re-evaluated for tumor typing morphologically. Among these, 126 cases [108 NSCLC-not otherwise specified (NOS), 11 squamous cell carcinoma (SCC), 7 adenocarcinoma (ADC) and 1 adenosquamous carcinoma (ADSC)] were selected for IHC examination. These cases were stained for thyroid transcription factor-1 (TTF-1)+Napsin A and p63+CK5/6 using a double IHC staining method and stained for desmoglein-3 (DSG-3), CK7, CK20 and CDX2 using a conventional IHC method. Diagnostic concordance between 40 resection specimens and their corresponding biopsy specimens were also compared.
366 (50.6%) of 724 cases diagnosed as NSCLC were morphologically typed and 358 (49.4%) of them were classified as NSCLC-NOS. After IHC examination, while 74 (69%) of 108 NSCLC-NOS cases could be typed, 34 (31%) of cases could not be classified in spite of IHC examination. TTF-1 expression in 100% of ADC and 7% of SCC, Napsin A expression in 77% of ADC and 2% of SCC, p63 expression in 93% of SCC and 28% of ADC, CK5/6 expression in 96% of SCC and 9% of ADC, DSG-3 expression in 21% of SCC and none of ADC and CK7 expression in 89% of ADC and 30% of SCC were observed. CDX2 positivity was detected in 14.3% of ADC, 17.9% of SCC and 29.4% of NSCLC-NOS cases. 5.6% of NSCLC-NOS cases expressed CK20. Diagnostic concordance compared between biopsy and resection specimens in 40 cases was found to be 65% (100% with respect to SCC).
A panel of TTF-1, p63 and CK5/6 allows to reliably classify 70% of poorly differentiated NSCLC cases in small biopsy specimens.
Clinical trial identification
Legal entity responsible for the study
Ankara University Scientific research foundation
All authors have declared no conflicts of interest.