A very rare presentation of synovial cell sarcoma arising from the tendon sheath of flexor hallucislongus tendon and causing secondary erosion of calcaneum.

Synovial cell sarcoma is a rare variety of soft tissue tumour. Very few cases of this tumour affecting the tendon sheath have been reported so far. We report a rare presentation of synovial cell sarcoma of the flexor hallucislongus tendon in a 35-year-old female. She presented with a painful lump (tumour) arising from postero medial aspect of the right ankle. The mass produced erosion of the overlying calcaneum over the time of one year. She was managed surgically by enucleation of the tumour followed by augmentation of calcaneum with bone cement.