Timely and Accurate Diagnosis of Rare Metastatic Melanoma With Pulmonary Vascular, Cardiac, and Brain Involvement: Improving Diagnostic Access and Minimising Risk.

We present a patient in his 40s with a history of melanoma excised 14 years prior, who developed persistent cough, haemoptysis, and chest pain. Imaging revealed a right hilar mass extending into the pulmonary artery and left atrium. PET-CT confirmed high 18F-fluorodeoxyglucose (FDG) uptake consistent with active tumour, while brain MRI showed metastatic lesions and cardiac MRI revealed intracardiac extension. An initial CT-guided lung biopsy was non-diagnostic. Due to diagnostic uncertainty, full anticoagulation (given the difficulty in distinguishing tumour from thromboembolism), and high procedural risk, endobronchial ultrasound (EBUS) was performed under conscious sedation. EBUS successfully provided a tissue diagnosis of BRAF-positive metastatic melanoma. The patient was initiated on ipilimumab and nivolumab immunotherapy, which was well tolerated with a favourable response. This case illustrates the critical role of PET-CT in distinguishing tumour thrombus from embolic disease and demonstrates the value of EBUS as a minimally invasive, safe, and effective diagnostic tool in high-risk settings. It also highlights how perseverance in diagnostic efforts can facilitate early treatment, even in complex and high-risk scenarios.