SARCOID-LIKE REACTION TO IMMUNOTHERAPY MIMICS PROGRESSIVE MALIGNANCY ON IMAGING

Abstract

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Recurrence or progression of thoracic malignancies can often be mimicked by numerous processes discovered on imaging including infection and inflammation. There is increasing evidence that immunotherapy can be associated with a sarcoid-like reaction causing enlarged, PET-avid lymph nodes that can resemble recurrence or progression of malignancy.1,2 We present a case in which progression of mesothelioma was suspected based on surveillance imaging, however, pathology was consistent with a sarcoid-like reaction in the setting of recent immunotherapy. CASE PRESENTATION: A 75-year-old female former smoker with a history of asbestos exposure subsequently diagnosed with epithelioid mesothelioma presents for evaluation of recurrence of her mesothelioma. She was initially diagnosed in 2018 when she presented with cough, pleuritic chest pain, weight loss and a pleural effusion. Diagnosis was made by thoracentesis and CT-guided biopsy of a left lower lobe nodule. Her initial stage was T2N0. She was treated with neoadjuvant Atezolizumab, Pemetrexed Disodium, Cisplatin followed by surgery (left pleurectomy, decortication, mediastinal lymph node dissection, and wedge resections for peripheral pleural nodules) and postoperative adjuvant Atezolizumab. Six months later, PET CT showed enlarged hypermetabolic mediastinal lymph nodes, a perifissural nodule, enlarging pleural nodules, and increased pleural thickening, suspicious for disease progression. The patient was asymptomatic and evaluated with bronchoscopy and endobronchial ultrasound with transbronchial needle aspiration of multiple mediastinal lymph nodes. Pathology revealed granulomatous inflammation. Given her asymptomatic presentation, enlarged and PET avid mediastinal lymphadenopathy and recent immunotherapy exposure, she was diagnosed with a sarcoid-like reaction as a cause for her mediastinal lymphadenopathy. Adenopathy later resolved after withdrawal of immunotherapy. DISCUSSION: We present a case in which a sarcoid-like reaction to immunotherapy mimics metastatic progression of mesothelioma. In this case, tissue biopsy indicated a lower disease stage compared to imaging and allowed for local rather than systemic treatment options. CONCLUSIONS: Recognition of sarcoid-like reactions is important during surveillance and restaging of malignancy in patients undergoing treatment with immunotherapy. This case illustrates the importance of direct tissue sampling in diagnosing mimickers of thoracic malignancies. Reference #1: Nishino M, Sholl LM, Awad MM, Hatabu H, Armand P, Hodi FS. Sarcoid-Like Granulomatosis of the Lung Related to Immune-Checkpoint Inhibitors: Distinct Clinical and Imaging Features of a Unique Immune-Related Adverse Event. Cancer Immunol Res. 2018;6(6):630-635. Reference #2: Tetzlaff MT, Nelson KC, Diab A, et al. Granulomatous/sarcoid-like lesions associated with checkpoint inhibitors: a marker of therapy response in a subset of melanoma patients. J Immunother Cancer. 2018;6(1):14. DISCLOSURES: stockholder relationship with Merck Please note: $20001 - $100000 Added 03/09/2020 by Adam Fox, source=Web Response, value=Ownership interest stockholder relationship with MMM Please note: $20001 - $100000 Added 03/09/2020 by Adam Fox, source=Web Response, value=Ownership interest No relevant relationships by Courtney Linkous, source=Web Response No relevant relationships by Gerard Silvestri, source=Web Response