Masson Tumour – A Rare Cause of a Hand Lump

Intravascular papillary endothelial hyperplasia, also known as Masson tumour, is a rare proliferative vascular lesion that can affect the hand. We report a patient who was operated on for a progressively enlarging soft tissue lump at the base of his thumb. Initially, it was thought to be a post-traumatic false aneurysm arising from a branch of the radial artery following blunt trauma. Subsequent histology revealed it to be a Masson tumour. We aim to highlight this rare pathology that can affect the hand and the diagnostic confusion we faced during the evaluation and management of this patient. <b>Level of Evidence:</b> Level V (Therapeutic).