77 Balancing Immunohistochemistry for Tumor Subclassification and Tissue Preservation for Molecular Study in Lung Core Biopsies

• Published in: American journal of clinical pathology 2018-01, Vol.149 (suppl_1), p.S34-S34
• Main Authors: Tang, Xiaoyu, Liu, Yongjun, Spencer, Amanda, Sharzehi, Setareh, Rassaei, Negar
• Format: Article
• Language: English
• Subjects: Adenocarcinoma; Biopsy; Immunohistochemistry; Lung cancer; Lung carcinoma; Non-small cell lung carcinoma; Preservation; Small cell lung carcinoma
• ISSN: 0002-9173; 1943-7722
• DOI: 10.1093/ajcp/aqx117.076

Abstract Objectives Information of subtyping and genetic alteration is important for treatment of non-small cell lung carcinoma (NSCLC). In some cases, immunohistochemistry (IHC) is needed for definitive subtyping. Molecular analysis determines subgroup of patients who can benefit from targeted therapy of NSCLC. Therefore, preservation of sufficient tissue sample for IHC and molecular studies is necessary, and pathologists play a pivotal role in accomplishing this task. Methods We retrospectively reviewed the institutional database for lung biopsies, focusing on primary lung adenocarcinoma between March 1, 2011, and July 31, 2016. The frequencies of IHC performed for diagnosis and molecular testing were compared. Results Review of 210 cases showed IHC was performed in 35.2%, with 64.8% diagnosed by morphology on hematoxylin and eosin (H&E) stain. The frequency of ordering IHC among three pathologists was 39.5%, 37.9%, and 27.7%, respectively, which was not significantly different. The IHC markers used included 54 cases for CK7, 49 cases for TTF-1, 42 cases for CK20, 20 cases for Napsin-A, 11 cases for p63, and seven cases for CK5/6. In 82.4% of the cases, markers for adenocarcinoma were used, while in 17.6% of cases, markers for both adenocarcinoma and squamous carcinoma were used. Molecular analysis was performed in 39.0% of the cases. Five cases had insufficient remaining tissue, with two of them having IHC performed. Thus, IHC did not have a significant impact on tissue preservation for molecular studies. Conclusion While there is no well-defined guideline in lung biopsy of NSCLC, our results show that IHC panel typically ordered by pathologists included one or two markers and IHC study did not have significant impact on tissue preservation for molecular studies in most cases.