Myxofibrosarcoma, also known as "myxoid malignant fibrous histiocytoma" is one of the most common soft tissue sarcomas in the extremities of adult patients. Most cases are characterized by a multinodular and/or infiltrative pattern with a tendency to infiltrate along fascial planes. We report a case of myxofibrosarcoma with an unusual presentation. Despite the clinical impression of a complete surgical resection, microscopic sarcomatous foci extended along the perineurium of the external saphenous nerve proximally up to 20 cm away from the main tumour. This unique case represents an extreme example of the locally agressive behaviour of soft tissue sarcomas and illustrates the microscopic tumour invasion along major nerves.