Synonym- Endothelial sarcoma of bone
Swings sarcoma is an uncommon but highly malignant sarcoma arising from endothelial cells in the bone marrow.
Age incidence- usually between 10 and 20 years.
Common sites- shaft of femur, tibia, fibula, humerus or clavicle.

Pathology:
The tumour tissue is soft and vascular. As it expands it gradually destroys the bone substance. There is striking reaction beneath the periosteum, where abundant new bone is formed in successive layers. Macroscopically the tumour is lobuloted and often fairly large. It may look Grey (like brain) or red (like red current jelly) if hemorrhage occur into it. Microscopically, sheets of small dark polyhedral cell with no regular arrangement and no ground substance are seen.

Clinical Feature:
  1.              Pain- Often throbbing is character with rapidly increasing swelling over the shaft of a long bone.
  2.              Pyrexia, warm, tender swelling which is fusiform in shape and firm in consistency.

Investigations:
1. X-ray                             a.  Onion-peel appearance
                                           b.  Sunray appearance and codman’s traingles are also present.
2. CT & MRI                    -   Reveal both osseous & extra osseous component of tumour.
3. Chest X-ray P/A view -   Show pulmonary metastesis.
4. Radioisotope scan       -   Markedly in creased uptake of the isotope in the region of the tumour.
5. FNAC.

Differential Diagnosis
1.          Subacute osteomyelitis
2.          Syphilitic osteoperiostitis
3.          Reticulur cell sarcoma
4.          Metastetic neuroblastoma.
  
Treatment:
The best results are achieved by a combination of all three methods a course of preoperative chemotherapy; then wide excision (or amputation) if the tumour is in a favorable site or radiotherapy followed by local excision if it is less accessible and then a further course of chemotherapy for 1 year.