Parosteal lipoma is a rare benign soft tissue mesenchymal tumour that may impair limb motor function when located adjacent to neurovascular structures. We report a case of a woman in her 80s with a long-standing lesion in the forearm and consequent sensory and motor function changes. She was admitted for an elective excision of the lipoma. Postoperative evolution was favourable, with marked improvement of limb function. Our aim in sharing this case is to create awareness of these rare deep-seated lipomas that might originate nerve palsy and should therefore be excised as soon as possible to avoid neurological damage.