SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Epithelioid Hemangio-Endothelioma (EHE) is a rare low to intermediate grade malignant vascular tumor with metastatic potential [1]. Here, we present a case of primary Pulmonary EHE with pleural involvement and lymph node metastasis. CASE PRESENTATION: A 52-year old female, non-smoker presented to our ED 2 months ago with right lower rib cage pain and dyspnea. CTA chest at that time showed findings consistent with RUL consolidation and trace right sided pleural effusion [Fig.1]. She received total of 15 days of antibiotics which did not improve the symptoms and subsequently presented to ED 20 days later with worsening pain and dyspnea. Repeat CT chest showed persistent RUL consolidation with increase in effusion size. Thoracentesis was performed twice, and pleural fluid analyses revealed a exudative effusion with some atypical cells and negative flow cytometry on two occasions. Patient underwent transbronchial biopsy which was negative for malignancy. PET-CT demonstrated right perihilar upper lobe mass-like area along with right paratracheal lymph node involvement [Fig.2,3]. Due to high suspicion for malignancy, patient underwent CT guided transthoracic biopsy. Pathology showed malignancy with EHE that was confirmed with pathology lab from University of Michigan. Patient was discharged to follow up at Cleveland Clinic for further staging and management and is currently under evaluation for starting on chemotherapy. DISCUSSION: EHE has a low prevalence with only a little over 100 cases reported since it was first described in 1975 [2]. Theoretically, it can develop in any tissue but occurs primarily in the soft tissues, liver and rarely in the lung [2]. Pulmonary EHE (PEHE) presents as either a solitary nodule or more often as multiple small nodules [2,3]. Most patients require surgical biopsy for histopathological confirmation. Histopathologically, EHE is characterized by the features of epithelioid cells, but originates from vascular endothelial cells. [2] This is evidenced by the presence of some or all of the vascular endothelial markers (CD31, CD34 and factor VIII) on immunohistochemistry [4]. The prognosis is very unpredictable, with life expectancy ranging from 1-15 years [5]. However, presence of respiratory symptoms and pleural effusion at diagnosis is associated with worst prognosis, with a median survival of less than 1 year [6]. CONCLUSIONS: PEHE has a variable presentation, clinical course, and imaging appearance. Its rarity adds to the challenge of diagnosis. PEHE should be considered in the differentials when the patient presents with pulmonary manifestations and there is no apparent diagnosis found. Reference #1: Travis WD, Brambilla E, Nicholson AG, et al. The 2015 World Health Organization Classification of Lung Tumors: impact of genetic, clinical and radiologic advances since the 2004 classification. J Thorac Oncol Reference #2: Dail D, Liebow A. Intravascular bronchioloalveolar tumor. Am J Pathol 1975;78:A6–7. 2015;10:1243–60. Reference #3: Weiss SW, Enzinger F. Epithelioid hemangioendothelioma a vascular tumor often mistaken for a carcinoma. Cancer 1982;50:970–81. DISCLOSURES: No relevant relationships by Salil Avasthi, source=Web Response No relevant relationships by DEEPTI AVASTHI, source=Web Response No relevant relationships by Upneet Chawla, source=Web Response No relevant relationships by Rathnavali Katragadda, source=Web Response No relevant relationships by Leela Krishna Vamsee Miriyala, source=Web Response