C80-29 A Case of Isolated Endobronchial Metastasis Seven Years After Melanoma In Situ Excision

Abstract Roughly 4% of endobronchial tumors are metastases from an extrapulmonary source 1. Rarer still is endobronchial melanoma metastasis, accounting for roughly 4.5% of that 1. Clinically, melanoma metastasis should remain on the differential for patients with recurrent pneumonia and a history of any skin cancer. Diagnosis is made with biopsy, and treatment consists of immune checkpoint inhibitors, palliative measures like endoscopic debulking and radiation, and surgical resection in certain cases. We present an 84-year-old woman with melanoma in situ excised from her forehead in 2018. She presented with three months of worsening cough and dyspnea with chest x-ray demonstrating a left lower lobe (LLL) pneumonia and parapneumonic effusion. Subsequent CT chest revealed total occlusion of the LLL bronchus, concerning for post-obstructive pneumonia from endobronchial malignancy. Bronchoscopy revealed a necrotic, fungating lesion. Biopsy confirmed malignant melanoma, though all lymph nodes and lavage samples were negative. Brain MRI and full-body CT were negative for additional metastases, rendering a final diagnosis of stage IV (TxNxM1b) melanoma with isolated endobronchial metastasis, likely from the original melanoma. Treatment consisted of nivolumab, relatlimab, lung radiation, and regular surveillance.This case adds to the literature in three ways. First, it represents isolated rather than widespread disease. In the two other endobronchial metastasis cases we found, the patient was diagnosed with metastatic melanoma at presentation 2 or had concurrent parenchymal metastases 3. One other report describes isolated endobronchial metastasis 4, though with poorer outcomes (death three months later). Second, this metastasis occurred seven years after the original excision. Although there is one case of endobronchial metastasis 40 years later 4, this is exceedingly rare. Third, the immunotherapies in this case are novel: the FDA approved nivolumab in 2014 and relatlimab in 2022. Prior reports 2-4 predate one or both agents. 1 Marchioni A, Lasagni A, Busca A, et al. Endobronchial metastasis: an epidemiologic and clinicopathologic study of 174 consecutive cases. Lung Cancer. 2014;84(3):222-228. 2 Abdul Hamid MF, Ban Yu-Lin A, Hassan TM, Mohammad N. Metastatic melanoma: a rare cause of central airway obstruction. BMJ Case Rep. 2017;2017:bcr2017221545. Published 2017 Nov 4. 3 Kobayashi S, Nakajima T, Iizasa T, Tsujimura H, Itami M, Kimura H. Pulmonary metastasis with endobronchial spread from sinonasal melanoma during a 9-year follow-up. Intern Med. 2010;49(8):777-779. 4 Karpathiou G, Froudarakis M, Da Cruz V, et al. Endobronchial melanoma metastasis 40 years after the excision of the primary cutaneous tumor: A case report. Medicine (Baltimore). 2017;96(34):e7931. This abstract is funded by: None