AN UNEXPECTED PULMONARY BIOPSY FINDING: SIMULTANEOUS SMALL CELL AND NON-SMALL CELL LUNG CANCER

Abstract

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: There are rare instances in which patients are found to have small cell and non-small cell lung cancer simultaneously. combined small cell lung cancer (cSCLC) is a rare type of SCLC in which a tumor contains SCLC and another non-small cell component. (1). Mutiple primary lung cancer (MPLC) occurs when malignancies develop at anatomically separate sites in the lungs. (2) CASE PRESENTATION: A 71-year-old female with a 60-year history of cigarette smoking presented with two weeks of generalized weakness and fatigue. A computerized tomography (CT) scan of the chest (Figure 1) revealed a large subpleural thick-walled cavitary mass in the right lower lobe (RLL) measuring 10 cm in the largest dimension. Additionally, there was a peribronchovascular mass in the right upper lobe with right-sided hilar and mediastinal adenopathy. Given the patient's clinical history and radiographic findings malignancy was suspected. Bronchoscopy with TBNA of mediastinal lymph nodes and the cavitary RLL mass was performed. Immunohistochemistry of the RLL mass biopsy was consistent with moderately differentiated invasive SCC. However, immunohistochemistry of the subcarinal lymph nodes biopsies revealed a different cancer type, high-grade SCLC. Based on the biopsy results, the diagnosis could have been either cSCLC in which separate biopsy sites sampled tumor different components or MPLC. Following these findings, the patient elected for comfort care. DISCUSSION: The ACCP guidelines for the diagnosis and management of lung cancer recommend that lung cancer diagnosis be made by the least invasive method possible which is often bronchoscopy with TBNA or endobronchial ultrasound-guided needle aspiration when extensive mediastinal disease is present. (3) In this case presentation, isolated sampling of subcarinal lymph nodes would have led to an incorrect or incomplete diagnosis, as the peripheral tumor site biopsy found an additional cancer type. While it is important to minimize morbidity associated with tumor tissue collection, bronchoscopists are also tasked with obtaining adequate samples for molecular and histologic subtyping of tumors. cSCLC and MPLC present a unique challenge because limited tissue sampling can lead to under diagnosis of these cancers. As such, these cancers are likely under underdiagnosed (1,2). When possible, maximizing tissue acquisition from tumor sites and nodal stations can help prevent misdiagnosis of cSCLC and MPLC. In both MPLC and cSCLC, characterization of all malignant cell lines is needed for the effective management of patients. CONCLUSIONS: cSCLC and MPLC are both important, likely under-diagnosed cancers to consider when investigating pulmonary tumors. Bronchoscopists should balance the need to minimize morbidity with the need for obtaining adequate tissue from nodal stations and tumor sites to prevent misdiagnosis of cSCLC and MPLC. REFERENCE #1: Zhao X, McCutcheon JN, Kallakury B, et al. Combined Small Cell Carcinoma of the Lung: Is It a Single Entity? Journal of Thoracic Oncology. 2018;13(2):237-245. REFERENCE #2: Chen C, Huang X, Peng M, Liu W, Yu F, Wang X. Multiple primary lung cancer: a rising challenge. J Thorac Dis. 2019;11(Suppl 4):S523-S536. doi:10.21037/jtd.2019.01.56 REFERENCE #3: Rivera MP, Mehta AC, Wahidi MM. Establishing the Diagnosis of Lung Cancer. Chest. 2013;143(5):e142S-e165S. doi:10.1378/chest.12-2353 DISCLOSURES: No relevant relationships by Amad Chohan, source=Web Response No relevant relationships by Hannah Hameed, source=Web Response No relevant relationships by Anjan Kumar, source=Web Response No relevant relationships by mohammad Razaq, source=Web Response No relevant relationships by Mashal Tahirkheli, source=Web Response