STRAIGHT TO THE LUNGS: UNUSUAL ETIOLOGY OF BILATERAL PULMONARY OPACITIES

Abstract

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma of chondroblastic origin by EWSR1-NR4A3 rearrangement. Its insidious nature frequently delays diagnosis. CASE PRESENTATION: 70-year-old male with a past medical history of hypertension presented with dyspnea at rest, fever, malaise, and productive cough without hemoptysis for one week. He is a retired electrical engineer with no recognized employment hazardous material exposure. He had mild recent mold exposure from home woodcutting, tree burning. Physical exam was significant for bilateral posterior lower lobe rhonchi on pulmonary auscultation. Labs revealed highly elevated CRP, mild leukocytosis, lactic acidosis, and elevated procalcitonin. Chest radiographs demonstrated left lower lobe infiltrates and multiple, bilateral soft tissue densities. He was started on broad-spectrum antibiotics for presumptive pneumonia. Chest CT demonstrated numerous bilateral noncalcified pulmonary nodules, the largest in the right lung measuring 3.7 cm, and the largest in the left lung measuring 3.6 cm; no hilar or mediastinal lymphadenopathy. Bronchoscopy and bronchoalveolar lavages showed no endobronchial lesions and were negative for cytological abnormalities or infection with negative bacterial, fungal, and mycobacterial cultures. CT-guided left lower lobe nodule biopsy was suggestive of low-grade myxoid neoplasm. PET-CT demonstrated diffuse pulmonary nodule uptake in addition to a hypermetabolic mass lesion in the left lateral thigh, 3.2 x 2.8 cm, with a maximum uptake value 3.9. Video-assisted thoracoscopy guided wedge resection of left lower lobe was then performed. Immunohistochemical staining from lung tissue was positive for vimentin, CD117, bcl2, p63, CD138. Fluorescence in situ hybridization revealed the presence of a fusion transcript and chromosomal rearrangement involving EWSR1 from t(9;22)(q22;q12), pathognomonic for extraskeletal myxoid chondrosarcoma. Biopsy of the left thigh mass confirmed primary disease origin. Patient followed up with an orthopedic oncologist and is currently on sunitinib, considering future wide local excision. DISCUSSION: Soft tissue sarcomas are rare, comprising 1% of adult malignancies with EMC accountable for <2% of all soft tissue sarcomas. Chromosomal reciprocal translocation of t(9;22)(q22;q12.2) resulting in fusion of EWSR1 to NR4A3 is responsible for carcinogenesis in 70-80% of cases, whereas another fusion gene, RBP56/TEC, is associated with translocation of t(9:17)(q22;q11.2) and comprises 15% of EMC. It has a high propensity to develop pulmonary metastases. Previous published reports have confirmed the therapeutic activity of sunitinib in EMC. Genotype/phenotype analyses support a correlation between chemotherapy response and EWSR1-NR4A3 fusion. CONCLUSIONS: We reported this rare etiology, its pathology and the diagnosis of bilateral pulmonary opacities, found to be metastatic EMC. Reference #1: Stacchiotti S, Pantaleo MA, Astolfi A, et al. Activity of sunitinib in extraskeletal myxoid chondrosarcoma. Eur J Cancer. 2014;50(9):1657–64. Reference #2: Hisaoka M, Hashimoto H. Extraskeletal myxoid chondrosarcoma: Updated clinicopathological and molecular genetic characteristics. Pathol Int. 2005;55:453–63. Reference #3: Oliveira AM, Sebo TJ, McGrory JE, Gaffey TA, Rock MG, Nascimento AG. Extraskeletal myxoid chondrosarcoma: A clinicopathologic, immunohistochemical, and ploidy analysis of 23 cases. Mod Pathol. 2000; 13:900–8. DISCLOSURES: No relevant relationships by Phyo Kyaw, source=Web Response No relevant relationships by Thomas Massutti, source=Web Response No relevant relationships by Peter White, source=Web Response