Although benign, these tumours can show recurrence and malignant transformation (carcinoma ex-pleomorphic adenoma), primarily in cases where only a biopsy or incomplete excision were performed.
Although classified as benign, its locally invasion, distant metastasis and malignant transformation pose a therapeutic challenge in oral and maxillofacial surgery [ 2].
Ameloblastoma is a frequent odontogenic benign tumor characterized by local invasiveness, high risk of recurrence and occasional metastasis and malignant transformation.
Hepatocellular adenomas (HCAs) are benign hepatic neoplasms of hepatocellular origin, but must be differentiated from FNH because of their risks of haemorrhage and malignant transformation to HCC.
HCAs are benign monoclonal neoplasms classified into four subtypes based on immunohistochemistry. Inflammatory HCAs show an atoll sign with a risk of bleeding and malignant transformation.
Myxoid fibroadenomas and DAs are benign and no malignant transformation has been reported among CNC patients [36, 38].
Thus, in the chapter on bone tumours, the authors consider pre-existing conditions and aetiologic factors together and the account of soft tissue tumours concerns benign to malignant transformations, progression from low-grade to high-grade malignancies, and specific chromosomal translocations.
Despite the identification of these key parathyroid tumor suppressor genes, the mechanisms and pathways that distinguish benign from malignant transformation of the parathyroid remain elusive.
The decrease or deletion of the expression of E-cadherin leads to the loss of contact inhibition and unrestricted hyperplasia, the loss of intercellular junction with, stronger invasive ability, enhanced tumor cell diffusion and metastasis, as well as benign tumor malignant transformation in some extreme cases [21], [22], [23].
