[A rare extra-skeletal myxoid chondrosarcoma of the lower leg - is amputation absolutely necessary]

Sarcomas represent less than 2 % of all malignancies. Special challenges are bone sarcomas in extra-skeletal localisation. The aim of this case report is to show the management of an extraordinary extra-skeletal myxoid chondrosarcoma based on a case report with references from the literature.

After a delay in diagnostics for 1.5 years, an MRI scan taken in a 42-year-old male patient with progressive swelling of the left calf showed a soft-tissue tumour in the proximal part of the muscle. Histopathological investigation of a percutaneous biopsy revealed a chondrosarcoma. En-bloc-resection (R 0) of the rear superficial compartment was performed (specimen weight 1 370 g; tumour size 11.5 x 9.5 x 8 cm) leading to the definitive diagnosis of an extra-skeletal myxoid chondrosarcoma. The patient was discharged with a bland wound 8 days after surgery. At 4 weeks postoperatively, the patient received adjuvant radiotherapy with a 56-Gy boost. During the follow-up period of 28 months, there have been neither signs of local tumour recurrence nor distant metastases.

The myxoid chondrosarcoma is a rare tumour lesion, and according to the literature, only 2 % occur outside of the skeleton. The accurate diagnostic and therapeutic algorithm allowed a precise preparation for surgery and made amputation obsolete. Compartment resection preserving the main neurovascular bundles as well as enabling an early mobilisation resulted in both sufficient radical resection status and adequate postoperative motor function. Intraoperative clip-marking of the former tumour bed is considered a key point for the focused radiotherapy.

Each persistent soft tissue swelling must be appropriately diagnosed using adequate imaging and even biopsy (in case of a doubtful finding), which should be performed with definitive surgery in mind.