Of 3000 patients diagnosed with primary malignant bone tumours and treated at our unit over the past 25 years, 234 (7.8%) were considered to be spindle cell sarcomas of bone (ie not osteosarcoma, chondrosarcoma, Ewing’s, chordoma or adamantinoma). We have analyzed their management and outcomes.

The diagnosis of these cases varied with fluctuations in the popularity of conditions such as MFH, fibrosarcoma and leiomyosarcoma with the passage of time. Treatment was with chemotherapy and surgery whenever possible. 36 patients had metastases at diagnosis and 17 had palliative treatment only because of age or infirmity. The most common site was the femur followed by the tibia, pelvis and humerus. The mean age was 45 and the mean tumour size 10.2cm at diagnosis. 25% of patients presented with a pathological fracture. Chemotherapy was used in 70% of patients the most common regime being cisplatin and doxorubicin. 35% of patients having neoadjuvant chemotherapy had a good (> 90% necrosis) response. The amputation rate was 22% and was higher in patients presenting with a fracture and in older patients not having chemotherapy.

With a mean follow up of 8 years the overall survival was 64% at 5 yrs and 58% at 10 yrs. Adverse prognostic factors included the need for amputation, older age and poor response to chemotherapy as well as a pathological fracture at presentation. The few patients with angiosarcoma fared badly but there was no difference in outcomes between patients with other diagnoses.

We conclude that patients with spindle cell sarcomas should be treated similarly to patients with osteosarcoma and can expect comparable outcomes. The histological diagnosis does not appear to predict behaviour.

Introduction: Parosteal osteosarcoma is a rare, mostly low grade tumor arising from the surface of the bone. The aim of the study was to establish risk factors for local recurrence (LR) and death.

Method: Retrospective review of a prospectively collected database with complete up-to-date follow up.

Results: 63 patients were diagnosed and treated at our centre from 1978 to 2007. The most common site was the femur (37) followed by the tibia (10) and humerus (9). The median size was 7cm (2 – 16). At the time of diagnosis 27 (43%) were low grade, 13 (21%) were low grade but had invaded the medullary canal and 8 (13%) had a high grade component; the data was missing in 15 patients (24%). All patients were operated.

LR arose in 11 patients (17.5%) at a mean of 38 months and was related to surgical margins. There were no LR in the 26 wide resections, but the risk of LR was 20% in those with a marginal and 46% in those with an intralesional excision. LR appeared as a higher grade than the primary tumor in 3 patients (27%).

9 (14.3%) patients developed metastases at a median of 22 months (6 – 123). Five patients developed both LR and metastases. Seven patients died from the tumor, 2 patients are alive with metastatic disease.

None of the patients with a low grade tumor and wide or marginal margins died of tumor, but 2 patients (18%) operated intralesional died of tumor.

Discussion: There was a statistically significant relationship between surgical margins and LR (p< 0.001). All patients with low grade parosteal osteosarcoma operated with wide margins have been cured. LR appeared often in higher grade than the primary tumor. Patients with low grade tumor and intralesional margins had 18% risk to tumor-ralated death.