LAUSR

A 67-year-old man underwent endovascular embolization of a recurrent left mandibular plasma cell tumor. Post-procedure, he developed tachycardia and hypotension. A CT scan of his abdomen and pelvis was performed to exclude a retroperitoneal hemorrhage. The CT scan incidentally revealed a 20 × 18 mm calcified exophytic lesion in the posterior mediastinum, appearing to arise from the esophagus (Fig. 1). The patient was asymptomatic of this lesion. The patient’s past medical history included multiple myeloma for which he underwent chemotherapy and stem cell transplantation in 2007. He was also diagnosed with paroxysmal supraventricular tachycardia and melanoma of the ear. His only regular medication was metoprolol. The patient underwent a previous partial embolization of the left mandibular plasma cell tumor in 2014 and had a 10-pack year history of cigarette smoking. On gastroscopy, 34 cm from the incisors was the impression of a subepithelial lesion with normal overlying mucosa. A radial echoendoscope revealed a well-defined 20 × 15 mm hypoechoic lesion compressing but not arising from the esophagus. Within the lesion, there were multiple internal tubular structures giving a “bag of worms” appearance (Fig. 2). There was no mediastinal or coeliac lymphadenopathy. An EUS-guided (endoscopic ultrasound) FNA (fine needle aspiration) was performed. In-room cytopathology revealed findings consistent with a pulmonary hamartoma (Fig. 3). The patient proceeded to bone marrow transplantation for treatment of multiple myeloma. Differential diagnoses include plasmacytoma, lymphoma, granuloma, lung cancer, pulmonary hamartoma, and lung metastases. Pulmonary hamartomas are benign neoplasms of the lung that rarely cause symptoms and are often discovered incidentally. They are usually located peripherally and typically appear as wellcircumscribed nodules or masses with either smooth or lobulated margins. In most cases, < 4 cm in diameter. There are currently no documented case reports of EUS-guided FNA of pulmonary hamartomas. This case demonstrates a surprising diagnosis as well as the utility of EUS FNA in biopsy of unknown primary mediastinal lesions and diagnosing diseases with mediastinal lymph node involvement (i.e. tuberculosis and sarcoidosis).