Metastatic melanoma presenting as intravenous tumour thrombus.

Tumour thrombus is a complication that occurs when a malignancy invades into the vasculature, occluding its lumen. Here, we present a rare case of melanoma tumour thrombus of the great saphenous vein of the left thigh, which was diagnosed on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography and ultrasound-guided biopsy, and responded well to immunotherapy with pembrolizumab.