C80-23 Solitary Pulmonary Metastasis From Rectal Adenocarcinoma Managed by Robotic Right Middle Lobectomy Complicated by Chylothorax

Abstract Background Isolated pulmonary metastasis of colorectal cancer is rare with incidence of 1.7% and 7.2%. We present a case of a solitary, FDG-avid right middle lobe nodule in a patient with rectal adenocarcinoma, managed successfully with robotic right middle lobe lobectomy followed by postoperative complication of chylothorax. Case Description A 34-year-old physically active, non-smoking male was referred for pulmonary evaluation after an incidental 1.7 × 1.7 cm right middle lobe solid nodule was detected on staging CT for newly diagnosed rectal adenocarcinoma. He was asymptomatic apart from mild weight loss. Past history included splenectomy for a benign splenic mass and cholecystectomy. Physical examination and pulmonary function tests were unremarkable. CT chest/abdomen/pelvis showed irregular circumferential rectal wall thickening with perirectal lymphadenopathy and a solitary subpleural RML nodule, without hepatic or distant metastases. PET/CT demonstrated FDG-avid uptake in the rectal lesion (SUVmax 14.9) and RML nodule (SUVmax 4.7), with no mediastinal or extrathoracic disease. Following neoadjuvant therapy, the patient underwent abdominoperineal resection. Persistent PET uptake in the RML prompted robotic-assisted right middle lobectomy with lymph node sampling (stations 4R, 7, 8, 13). Histopathology revealed a 1.5 cm adenocarcinoma positive for CK20 and CDX2 and negative for CK7, TTF-1, and Napsin A, consistent with metastatic colorectal adenocarcinoma. All sampled lymph nodes were benign. The postoperative course was complicated by persistent high-output chylothorax refractory to conservative management. Robotic-assisted right VATS thoracic duct ligation with doxycycline pleurodesis was performed. Intraoperative indocyanine-green lymphangiography localized the chyle leak to the prior 4R nodal dissection site, which was successfully ligated, resulting in complete resolution. The patient recovered fully, with preserved pulmonary function and exercise tolerance, and continued systemic oncologic management. Concluion The absence of hepatic metastases should not preclude evaluation for pulmonary metastases, even in young and otherwise healthy patients, given the rarity of such presentations. Robotic bronchoscopy lobectomy is a new and minimally invasive approach for precise anatomic dissection though lymphatic injury and chylothorax remain risks. Prompt recognition and indocyanine green (ICG)-guided thoracic duct ligation enable accurate leak localization and effective management. This abstract is funded by: None