Background: A 48-year-old woman was referred to our hospital for evaluation of a soft tissue mass at her right ankle. At initial presentation, 5 years earlier, her general practitioner thought of a benign lesion and suggested to remove the mass. At the time, no additional imaging was requested. Over the years, the swelling was slowly growing but remained painless. Now, on clinical examination, a mass lesion was seen, located posterior of the lateral malleolus, consisting of a firm mass fixed to the surface underneath. The estimated size of the tumor was 2 x 6 cm, which gave rise to suspicion of a malignancy.