SOLITARY PULMONARY NODULE PRESENTING AS A SARCOMATOID CARCINOMA IN A PREGNANT WOMAN: A DIAGNOSTIC DILEMMA

Abstract

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: The majority of lung cancers are made up of epithelial tumors with adenocarcinoma being the most common. Sarcomatoid carcinoma of the lung is rare and is present in only 0.52% of all diagnosed cases of NSCLC. The WHO has classified mesenchymal tumors of the lung into vascular, vessel-associated tumors and nonvascular spindle cell tumors. The etiology of sarcomas is usually genetic in nature, a result of environmental toxin exposures, or due to a mutation. CASE PRESENTATION: A 37 year-old female who was six months pregnant, presented with one episode of hemoptysis in the setting of a chronic cough. No history of lung disease or other health conditions. No prior smoking or vaping history. Initial chest X-ray revealed a right lung nodule within the superior segment of the right lower lobe, initially concerning for a pulmonary hamartoma or carcinoid. CT chest was delayed due to her pregnancy, and ultimately deferred until after delivery three months later which showed an enlarging heterogeneous, 3.5 cm x 3.4 cm right lower lobe mass. She refused CT/PET as she was breastfeeding her newborn. She eventually agreed to surgery and underwent video-assisted thoracoscopic surgery (VATS) with mediastinal and regional lymphadenectomy and RLL lobectomy. Pathology revealed a low-grade sarcoma, with multiple analyses concerning for low-grade endometrial stromal sarcoma (ESS) vs. vascular neoplasm. Further molecular analysis with FISH confirmed low-grade vascular sarcoma with regional lymph node involvement (ESS was negative). Her PET scan following surgery was negative for any disease. DISCUSSION: Our patient had a RLL mass showing a malignant spindle cell neoplasm with a positive right hilar lymph node favored to be a low-grade sarcoma. Given its morphology, the differential diagnoses were low-grade endometrial stromal sarcoma, malignant peripheral nerve sheath tumor (MPNST), solitary fibrous tumor (SFT), inflammatory myofibroblastic tumor, PEComa, and synovial sarcoma. A definitive diagnosis is of utmost importance as certain types of sarcoma confer a poorer prognosis. For example, primary pulmonary synovial sarcoma is usually extremely aggressive with a 5-year survival rate of only 50%. CONCLUSIONS: This case is very unique in a few ways. First, it is an uncommon cause for a solitary pulmonary nodule along with being an uncommon malignancy. Second, it presents a complicated diagnostic dilemma in a pregnant patient who was reluctant to have diagnostic imaging and procedures that would have aided in the diagnosis. Reference #1: Hashimoto H, Tsugeno Y, Sugita K, Inamura K (2019) Mesenchymal tumors of the lung: diagnostic pathology, molecular pathogenesis, and identified biomarkers. J Thorac Dis 11:S9–S24 Reference #2: Rahouma M, Kamel M, Narula N, Nasar A, Harrison S, Lee B, Stiles B, Altorki NK, Port JL (2018) Pulmonary sarcomatoid carcinoma: an analysis of a rare cancer from the Surveillance, Epidemiology, and End Results database. Eur J Cardiothorac Surg 53:828–834 DISCLOSURES: No relevant relationships by Bhavik Gupta, source=Web Response No relevant relationships by Bryan Stone, source=Web Response No relevant relationships by Christopher Wyckoff, source=Web Response