Goals: Sarcomatous degeneration of giant cell tumours (GCT) occurs rarely. It occurs in less than 1% of the cases, and most of them are GCT previously treated with radiotherapy. The goal of this presentation is to review the CGT cases treated at our unit that have evolved towards malignization.

Methods: Retrospective study of 96 GCT treated at our Hospital between 1983 and 2005. 5 presented sarcomatous degeneration in their evolution. These were the cases of 3 men and 2 women with a mean age of malignization of 42 years (32 years – 54 years). The median follow-up period was 155 months (5 months – 209 months). 3 cases affected the distal femur, one case affected distal radius and one case affected proximal humerus, with a slight tendency to the right hemibody. The primary treatment for GCT in these patients was curettage and bone graft. Only one case had received previous radiotherapy. In the same period of time we had two cases of lung dissemination of CGT with typical histology, without previous malignization of tumour.

Results: Malignization takes place, on average, at the 1.8th recurrence (1.3). Histologically, we find 3 osteosarcomas and 2 indifferentiated tumours. Three patients developed distant dissemination; 2 patients died due to lung metastases, with a mean time between the first surgery and the sarcomatous degeneration of 90 months (40 monts – 183 months) and a mean time between malignization and mestastases of 22.3 months (9 months – 34 months) The treatment, once the malignization was diagnosed, consisted in wide resection and substitution with mega-arthroplasty in cases of distal femur and osteoarticular graft at the shoulder. 2 cases required amputation of the affected limb due to irresecable recurrence in soft tissues.

Conclusions: There is no predictive criteria of which type of primary typical CGT will evolve into sarcoma. The malignization always has as a result high grade sarcomas, with a high tendency to hematogenous dissemination. When lung metastases appear the survival prognosis is a number of months. We must suspect malignization of a benign CGT when one of the relapses shows a very rapid growth with radiologic aggressive characteristics; in these cases we prefer wide resection of the tumour instead of curettage and thus we prevent the possible sarcomatous degeneration.