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Introduction: Pulmonary neuroendocrine tumors (NETs) comprise a spectrum of tumors ranging from indolent to highly aggressive neoplasm. This study aims to study the clinicopathological and immunohistochemical features of NETs and assess the sensitivity of various IHC markers. Materials and Methods: All consecutive cases of pulmonary NETs diagnosed from January 2016 to June 2019 were analyzed retrospectively. The routine hematoxylin- and eosin-stained sections along with immunohistochemistry (IHC) slides were reviewed. IHC was done using a panel of markers which included synaptophysin, chromogranin, CD56, thyroid transcription factor-1 (TTF-1), p-40, napsin-A, and ki67. Results: Of total number of 53 patients, diagnosis was made on biopsy in 40 patients and resection specimen in 13 patients. Small cell lung carcinoma was the most common (31 cases), followed by 16 cases of typical carcinoid, 5 cases of atypical carcinoid, and 1 case of combined SCLC. Both synaptophysin and chromogranin were positive in all the cases of typical carcinoid. Synaptophysin had better sensitivity than chromogranin in atypical carcinoid and small cell carcinoma. CD56 was positive in 8 out of 9 cases done. TTF-1 was negative in all the cases of typical carcinoid. The sensitivity of TTF-1 in small cell carcinoma was 85.19%. The mean Ki67 labeling index was 1.4%, 6.6%, and 65.6% in typical, atypical carcinoid, and small cell carcinomas, respectively. Conclusion: Synaptophysin was more sensitive than chromogranin, especially in atypical carcinoid and small cell carcinoma. TTF-1 along with high Ki67 differentiates small cell carcinoma from carcinoid. [ABSTRACT FROM AUTHOR]

Context: Percutaneous needle biopsy of lung (PCNBL) is advantageous over bronchoscopic biopsies to obtain adequate sample for peripheral lung lesions. Objective: The objective was to evaluate the diagnostic yield of image-guided PCNBL in the diagnosis of lung lesions and to classify lung carcinomas as per the recently proposed International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society/European Respiratory Society classification for small biopsies modified and adopted by the World Health Organization, 2015. Materials and Methods: A total of 280 image-guided PCNBL were analyzed. The radiological findings and routine hematoxylin and eosin (H&E)-stained sections along with immunohistochemistry (IHC) were analyzed in all the cases. Molecular testing was done depending on tissue diagnosis and availability. Results: Majority (81%) were diagnosed as malignant lesions, with adenocarcinoma (ADC) being the most common. More than 70% were diagnosed on H&E morphology alone, with thirty cases requiring IHC to categorize as ADC. Nearly 60% were categorized as squamous cell carcinoma on morphology alone and the rest required IHC. Though TTF1 showed higher sensitivity than napsin A, the latter is more specific. Both p63 and p40 were found to be highly sensitive for squamous cell carcinoma, but p40 was more specific than p63. Epidermal growth factor receptor could be evaluated on 94.4% of ADC samples, indicating good yield for molecular testing. Conclusion: PCNBL yields adequate sampling for tissue diagnosis and ancillary testing with minimal complications. The use of IHC markers reduces the number of non-small-cell not otherwise specified cases significantly. [ABSTRACT FROM AUTHOR]

Context: In this era of targeted therapy, it is important to distinguish the various subtypes of nonsmall cell lung carcinoma (NSCC). Diagnosis based on morphology alone is challenging in poorly differentiated carcinomas and core biopsies. Immunohistochemistry (IHC) helps in specifying the lineage for the subtype of NSCC. Till date, p63 is the most frequently used and sensitive marker for squamous cell carcinoma (SQCC). However, it is not specific and stains a subset of adenocarcinoma (ADC). Thus, a more reliable and specific marker is required for the diagnosis of SQCC. Objective: The objective of the study was to validate the diagnostic utility of p40 over p63 in differentiating pulmonary SQCC from ADC and NSCC-not otherwise specified (NOS). Materials and Methods: A total of 123 cases of NSCC were initially reviewed and subtyped blinded to the results of IHC. This was followed by a review of IHC slides which included p63, p40, thyroid transcription factor 1, Napsin-A, cytokeratin (CK) 5/6, and CK7. Results: There were 64 ADC, 19 SQCC, and 40 NSCC-NOS. IHC helped to confirm the morphological diagnosis in 62/64 ADCs and19/19 SQCCs. IHC classified the cases of NSCC-NOS into NSCC favoring ADC - 12 cases, NSCC favoring SQCC - 10 cases, and NSCC favoring AD-SQCC -- 4 cases. Both p63 and p40 showed near equal sensitivity for SQCC (100% and 97%, respectively), whereas p63 showed far lower specificity when compared to p40 (51.3% vs. 100%). Conclusion: The present study confirms and validates that p40 is equally sensitive but highly specific than p63 in detecting SQCC. Hence, we recommend the routine use of p40 instead of p63 for the definite categorization of NSCC of the lung. [ABSTRACT FROM AUTHOR]