Aims: Platelet-derived growth factor-alpha receptor (PDGFRA) and c-kit are tyrosine kinase receptors expressed in many neoplasms. We investigated protein expression in 34 giant cell tumours of bone and two specimens of lung metastases.
Methods: The expression of PDGFRA and c-kit was analysed by immunohistochemistry. Additionally, capillary sequencing of genomic DNA was performed to search for mutations in therapeutically relevant exons 12 and 18 of the PDGFRA gene and exons 9 and 11 of the c-kit gene.
Results: PDGFRA expression was detected in all specimens and all cellular components such as reactive osteoclast-like giant cells and neoplastic stromal cells. C-kit expression was found in six cases of giant cell tumour and one specimen of lung metastasis in all cellular components ranging from 5 to 50% (mean 4.8%, SD 12.4). A further 13 cases showed labelling of osteoclast-like giant cells. DNA sequence of exons 12 and 18 of the PDGFRA gene and exons 9 and 11 of the c-kit gene were not altered in these tumours.
Conclusion: PDGFRA and c-kit play a functional role in the growth of giant cell tumours of bone but genetic changes of therapeutically relevant exons of the PDGFRA gene and the c-kit gene are not seen in these tumours.