C78-20 A Rare Tumor in a Critical Location: Robotic Bronchoscopy for Epithelioid Hemangioendothelioma

Epithelioid hemangioendotheliomas (EHE) are rare soft tissue tumors that have a propensity for the liver, lungs, and bone (1). Among the known EHE cases, approximately 20% have pulmonary origin (2). Even in the absence of true pericardial metastasis, lesions that are in close proximity to the pericardium increase the complexity of tissue sampling for diagnosis. Here, we present a case of a 70-year-old woman with pulmonary EHE abutting the pericardium who underwent robotic bronchoscopy for diagnostic purposes. A 70-year-old woman, never-smoker, presented to our outpatient pulmonary office for evaluation of a persistent left lower lobe lung nodule first seen 6 years prior. Repeat CT scans of the chest showed a stable anteromedial left lower lobe lung nodule abutting the pericardium measuring 1.1cm x 1.6cm without lymphadenopathy. PET-CT scan did not show any FDG-avidity. A shape-sensing robotic assisted bronchoscopy (ssRAB) was performed with radial endobronchial ultrasound (REBUS), transbronchial needle aspirations (TBNA), and 1.1mm cryoprobe to obtain tissue samples of the lesion and the 11L lymph node. Cryobiopsy pathology showed clusters of epithelioid cells with lumen-like vacuolization and enlarged nuclei with smooth nuclear contours. The cells were embedded in an eosinophilic myxohyaline stroma with positive CD31, CD34, and ERG stains. Notably, TFE3 stain was positive and CAMTA1 was noncontributory. She was diagnosed with malignant epithelioid vascular neoplasm without high-grade features, most consistent with epithelioid hemangioendothelioma. Lymph node pathology was negative. She subsequently underwent thoracoscopic wedge resection of the LLL, and recovered uneventfully. Pulmonary epithelioid hemangioendotheliomas (PEH) are rare tumors with intermediate malignant potential typically caused by gene translocation. Due to their rarity, the literature on diagnosis is limited. In one case, a patient presented with angina and subsequently underwent CABG. Prior to the event, he was under surveillance for pulmonary nodules and pericardial masses attributed to granulomatous disease. During surgery, pericardial nodules were biopsied and consistent with EHE (2). Although our patient’s CAMTA1 stain was negative, she had positive TFE3, CD31, CD34, and ERG stains with histological components most consistent with the diagnosis. Given the high-risk location of our patient’s lesion, this case highlights the diagnostic difficulty and the procedural innovation required to obtain tissue sampling of this tumor without the guidance of advanced imaging such as cone beam CT. Cases of EHE involving the pericardium are exceedingly rare, and diagnosis is typically made by cardiothoracic surgeons rather than bronchoscopists.