Medullary Thyroid Carcinoma and Papillary Thyroid Carcinoma in the Same Patient as a Collision Tumour.

This is a collision tumour since lesions with features of MTC and PTC were detected in two different locations and separated by normal thyroid tissue. Germline point mutation of the RET gene had a potential role in the development of both MTC and PTC. On the other side, familial concurrent MTC and PTC without RET gene mutation was also published. Both RET and BRAF genes had a role in the development of the medullary and papillary collision tumours. We do not know the presence of BRAF gene mutation in this case report yet.