SPINDLE CELL CARCINOMA OF THE LUNG: A RARE, AGGRESSIVE TUMOR ELUSIVE TO TYPICAL DIAGNOSTIC METHODS

Abstract

SESSION TITLE: Monday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Spindle cell carcinoma is a subtype of sarcomatoid carcinoma, which encompasses a rare group of non-small cell lung carcinomas (NSCLC) that contain true sarcoma or sarcoma-like elements. Less than one percent of all lung cancers are sarcomatoid carcinomas. Here we present a case of spindle cell carcinoma that proved difficult to diagnose in the absence of surgical lobectomy. CASE PRESENTATION: A previously healthy 73-year-old female non-smoker presented to her primary care physician for a persistent non-productive cough. A chest radiograph revealed a large left upper lobe (LUL) mass. A computed tomography (CT) scan of the chest was performed, which demonstrated a 7.5cm LUL mass with a necrotic-appearing center and mediastinal lymphadenopathy. A subsequent positron emission tomography (PET)-CT scan showed uptake around the rim of the mass, sparing the center. She underwent bronchoscopy with endobronchial ultrasound-transbronchial needle aspirations of the mediastinal lymph nodes as well as radial probe ultrasound-guided transbronchial biopsies of the mass, with pathology showing inflammation and no evidence of malignancy. Shortly after the bronchoscopy, she became febrile with shaking chills. She was started on amoxicillin-clavulanate for possible lung abscess. A three-week follow-up CT scan showed no improvement in the size of the mass, so she underwent a CT-guided core biopsy, the pathology from which revealed extensive necrosis but was again negative for malignancy. A thoracentesis was also performed for a small left pleural effusion, during which 470ml of hemorrhagic fluid was drained. Fluid cytology and cultures were negative. Antibiotics were discontinued and she was referred for a lobectomy for definitive diagnosis. She underwent a left upper lobectomy, with pathology revealing an 8.5cm spindle cell carcinoma with visceral pleural invasion and involvement of the internal mammary and levels 5 and 6 lymph nodes, consistent with stage IV disease. A PET-CT performed three weeks post-operatively was highly concerning for residual or recurrent neoplasm in the left anterior chest wall. Radiation therapy was initiated. Genetic testing revealed a MET exon 14 deletion as well as a high expression of PD-L1. The patient is planning to start chemotherapy with pembrolizumab and crizotinib in the near future. DISCUSSION: This case highlights a rare form of lung cancer that was very difficult to diagnose, with false negative bronchoscopic biopsies and CT-guided percutaneous core needle biopsy. Such biopsy methods may not be capable of detecting epithelial and sarcomatous components, which could lead to a missed diagnosis. CONCLUSIONS: Given the high clinical suspicion for malignancy in this patient with a persistent and enlarging lung mass, a surgical biopsy was necessary to obtain a definitive diagnosis. Reference #1: Franks TJ, Galvin JR. Sarcomatoid carcinoma of the lung: histologic criteria and common lesions in the differential diagnosis. Arch Pathol Lab Med. 2010;134(1):49-54. Reference #2: Girard N, Cadranel J, Brambilla E, Cordier J-F. Rare primary lung tumors. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. United States: Elsevier; 2016:965-980. Reference #3: Tazelaar, HD. Pathology of lung malignancies. UpToDate. https://www.uptodate.com/contents/pathology-of-lung-malignancies?search=sarcomatoid%20carcinoma&source=search_result&selectedTitle=1∼29&usage_type=default&display_rank=1. Updated November 16, 2018. Accessed March 13, 2019. DISCLOSURES: No relevant relationships by Stephanie Hart, source=Web Response No relevant relationships by Leah Lande, source=Web Response No relevant relationships by Kriti Pathak, source=Web Response