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Background: The potentially curative and/or palliative therapy for non‐resectable lung cancer has evolved significantly over the past 2 decades. With the availability of targeted therapies, the need for precise sub‐typing of non‐small cell lung carcinoma (NCSLC) has become paramount. Objectives: As there are few data from South Africa, we aimed to determine utility of TTF‐1, napsin A, p63 and CK5 immunostaining on fine needle aspiration (FNA) cell block and formalin‐fixed paraffin‐embedded tissue biopsy specimens in subtyping NSCLC as adenocarcinoma and squamous cell carcinomas. Methods: All cases of NSCLC diagnosed during a 3‐year period were retrospectively identified. All FNA biopsy and formalin‐fixed paraffin‐embedded cases that were stained with TTF‐1, napsin A, CK5 and p63 were collected. A lung cancer registry was used to access and correlate clinical and radiological data. Results: We included 271 cases with diagnoses of adenocarcinoma of the lung (n = 201), squamous cell carcinoma of the lung (n = 53), unspecified NSCLC (n = 8) and other carcinomas (n = 9). TTF‐1 and napsin A had sensitivities of 99.0% and 91.9%, respectively, positive predictive values (PPVs) of 90.8% and 90.3%, respectively, and accuracies of 91.0% for adenocarcinoma of the lung. Napsin A had a higher specificity than TTF‐1 (90.2% vs 62.8%). Both CK5 and P63 had high sensitivities (95.4% and 97.9%, respectively) and negative predictive values of 96.4% and 96.8%, respectively, for squamous cell carcinoma of the lung. CK5 had a higher specificity than p63 (84.4% and 61.2%, respectively), PPV (80.4% and 70.8%, respectively) and accuracy (88.8% and 79.2%, respectively) for squamous cell carcinoma. Conclusion: All four immunostaining methods had high sensitivities. TTF‐1 and napsin A both had high PPV and diagnostic accuracy for adenocarcinoma of the lung, whereas CK5 had an equally high PPV and accuracy for squamous cell carcinoma of the lung. The specificity of napsin A for adenocarcinoma was higher than that of TTF‐1. The specificity of CK5 for squamous cell carcinoma was higher than p63. Utility of TTF‐1, NapsinA, Ck5 and p63 in distinguishing between Adenocacinoma and Squamous cell carcinoma, using fine needle aspiration cellblock material and paraffin embedded biopsy specimens in a resource limited setting. [ABSTRACT FROM AUTHOR]

Objectives: To assess immunohistochemical (IHC) stains differentially expressed between different types of lung cancer.Methods: We evaluated 16 different IHC stains in 209 prospectively included, surgically treated primary lung cancers, including 121 adenocarcinomas, 65 squamous cell carcinomas, 15 large-cell carcinomas, 5 adenosquamous carcinomas, 2 sarcomatoid carcinomas, and 1 small-cell carcinoma, using the tissue microarray technique.Results: Cytokeratin 5 (CK5) and P63 were both positive in 10% or more of the cells in 97% of the squamous cell carcinomas, with the former being positive (<10% of the cells) in only 2 non-squamous cell carcinomas. Thyroid transcription factor 1 (TTF1) and napsin A were positive in 10% or more of the cells in 88% and 87% of the adenocarcinomas, respectively, with 94% of the adenocarcinomas being positive in at least 1 marker. Fifteen percent of the adenocarcinomas were positive for estrogen receptor.Conclusions: CK5, TTF1, and napsin A are sensitive markers for squamous cell carcinoma and adenocarcinoma of the lung. [ABSTRACT FROM AUTHOR]

Background: The distinction of lung adenocarcinoma (ADC) from squamous cell carcinoma (SCC) has important therapeutic implications. Napsin A is a recently developed marker, which has shown high specificity for lung tissue in the surgical pathology specimens. In this study, we have evaluated whether the use of a panel of novel multiplex cocktails of TTF-1 + Napsin A and p63 + CK5 for dual color immunostaining will improve the diagnostic accuracy of lung adenocarcinoma and squamous cell carcinoma in fine needle aspiration (FNA) specimens, usually with relatively scant microfragments of diagnostic material. Materials and Methods: Formalin-fixed, paraffin-embedded, adequately cellular FNA cell blocks with a confirmed diagnosis of either ADC (n = 22), SCC (n = 20) or poorly differentiated carcinoma (PDC; n = 7), from a total of 49 consecutive cases, were studied. All these cases had subsequently confirmed diagnosis in biopsies or resection specimens. The sections were immunostained with two color methods of TTF-1 + Napsin A and p63 + CK5 multiplex cocktails. The presence of one or more unequivocal individual tumor cells with convincing brown nuclear TTF-1 and red cytoplasmic Napsin A staining, and cells with brown nuclear p63 and membranous / cytoplasmic CK5 staining were interpreted as 'positive'. Results: All 20 FNA cell blocks from SCC cases were positive for dual stain p63 + CK5 and negative for dual stain TTF-1 + Napsin A. The sensitivity and specificity of the dual immunoexpressions of p63 + CK5 for SCC of lung FNAs were both 100%. All 22 ADC cases were positive with dual stain of TTF-1 + Napsin A and negative for dual stain of p63 + CK5. On follow-up of the surgical pathology specimens, 22 cases were confirmed as ADC. The sensitivity of the dual immunoexpression of TTF-1 + Napsin A for ADC of lung FNAs was 100% and the specificity was also 100%. Of the seven PDC cases, five cases that were positive for dual stain p63 + CK5 and negative for dual stain TTF-1 + Napsin A could be categorized as SCC. Two of the seven (2 / 7) PDC cases were positive for dual stain TTF-1 + Napsin A and negative for dual stain p63 + CK5, consistent with ADC. Conclusions: Simultaneous coordinate or individual immunostaining for Napsin A / TTF-1 in ADC and p63 / CK5 in SCC demonstrated high sensitivity and specificity. The panel with multiplex Napsin A / TTF-1 and p63 / CK5 dual color immunostains could specifically subcategorize PDC into ADC and SCC in lung FNA specimens. Multiplex dual color Napsin A / TTF-1 and p63 / CK5 immunostaining is especially recommended for evaluation of FNA specimens with relatively scant cellularity. [ABSTRACT FROM AUTHOR]