New evidence for fibrocartilaginous dysplasia representing a variant of fibrous dysplasia.

Several types of tumours and tumour-like lesions are recognised. Their classification is based mainly on the cell or tissue differentiation pathway found within the lesion. Not all tumour cells in a bone tumour differentiate towards a single cell type. For instance, cartilage-producing cells and cartilaginous matrix are often found within osteosarcoma, and on rare occasions, cartilage can be found in fibrous dysplasia. Here, we discuss the presence of cartilaginous differentiation with fibrous dysplasia, its differential diagnosis and the use of molecular techniques to show that cartilaginous differentiation is an integral part of the lesion in that case, also known as fibrocartilaginous variant of fibrous dysplasia.