gms | German Medical Science

Introduction: Soft tissue sarcoma (STS) are with 1 % of all malignant tumours a rare malignant tumour entity. About 5 % are according the the actual recommendations from the WHO classified as undifferenciated pleomorphic sarcomas, fromerly classified as pleomorphic malignant fibrous histiocytoma. About 23 % of the patients with STS develop a local recurrence, which 80 % of the patients develop 2 years after initial surgery. Sofar, little is known about the genetic progression in these tumours. Aim of our study was to investigate the cytogenetic changes during tumour progression.

Materials and methods: Specimens from 7 different recurrences in a patient with malignant fibrous histiocytoma were collected. Changes in the copy number of DNA was detected by mCGH analysis. Out of the last recurrent tumor, as permanent cell line was established and characterized by immunohistochemistry and cytogenetic analysis. The malignant potential of the cell line was investigated by injecting tumour cells into immuno-compromised mice.

Results: Whereas tumour cells from the first recurrence showed only minor chromosomal alterations, a strong accumulation of chromosomal alterations became obvious during tumour progression. Alterations on chromosome 5, 6, 9, 12 and 20 could be observed from the 2nd recurrence on, deletions on chromosome 13 were identified from the 3rd recurrence on. Later during tumour progression we detected amplifications on chromosome 4 and 8q and deletions on 8p. In all recurrences number of amplifications were higher than the number of deletions. The established cell line showed a comparable morphological growth pattern, immunohistochemical and cytogenetic characters when compared to the original tumour. Four weeks after injection of tumour cells into mice palpable tumor masses were identified.

Conclusion: Our study demonstrates that tumour progression in STS is associated with the increase in genetic Imbalance. Therefor, the newly established cell line is a applicable model to investigate the malignant behaviour and tumor progression of STS.