1694 Endoscopic Ultrasonography With Fine-Needle Aspiration in the Diagnosis of Metastatic Rectal Adenocarcinoma in Left Atrium

Abstract

INTRODUCTION: Endoscopic ultrasonography(EUS) of the mediastinum with the use of fine needle aspiration(FNA) or biopsy can be used to characterize lesions that are within or adjacent to the esophageal wall, posterior and inferior mediastinum with minimal risk to the patient. EUS is an underutilized tool for identifying mediastinal masses and can help guide clinical decision making in patients with concerning lesions found on non-invasive imaging modalities. CASE DESCRIPTION/METHODS: A 71-year-old male with history of adenocarcinoma of the rectum with metastases to the liver and lung was treated with surgical resection and adjuvant chemotherapy. Patient responded well and was under regular surveillance when a new irregularly shaped abnormal soft tissue density measuring approximately 5.4 × 3.0 cm adjacent to the aorta and esophagus appearing to invade into the left atrium (Figure 1a) was found on a CT scan and confirmed on PET imaging. These findings favored rectal metastatic disease over thrombus but could not definitively rule out a new carcinoma. For that reason, an endoscopic ultrasonography was performed to determine the nature of the mass. A curvilinear array echoendoscope was used to visualize a 36 × 30 mm exophytic lesion within the left atrium which extended into the posterior mediastinum (Figure 2). Using Doppler to identify a vessel-free path, a 25-gauge needle was passed under ultrasound guidance through the esophagus and directly into the mass with the use of an endoscopic fine needle biopsy (FNB) device for three passes. Histopathological examination confirmed adenocarcinoma (Figure 3) and immunophenotype was compatible with colorectal primary which ruled out a pulmonary adenocarcinoma. DISCUSSION: The patient was determined to not be a surgical candidate due to the location of the mass and high risk nature of the surgery. The multidisciplinary team’s consensus was to repeat chemo-adjuvant therapy since he had responded so well previously. He received treatment and had follow up imaging six months after EUS diagnosis which showed decrease in size (Figure 1b) and activity of the mass. He is planned to have have stereotactic body radiation therapy to further decrease the size of the atrial mass. This case demonstrated how EUS with the use of FNA is a helpful tool in the prompt evaluation and confirmation of a mediastinal mass which allowed all physician’s involved in the care of the patient to develop and implement a treatment plan quickly. Watch the video: http://bit.ly/2Giu99S.