Bone invasion by oral squamous cell carcinoma

With regards to the anatomical relationships in the mouth, oral squamous cell carcinoma can invade the maxilla or the mandible. According to the TNM system, tumours that invade through cortical bone are classified as T4a, stage IVA. Bone invasion by oral squamous cell carcinoma most often occurs in tumours close to the bone or in larger and more advanced tumours. It is considered an adverse prognostic factor and it is often a diagnostic and therapeutic problem. Destruction of the bone tissue is mediated by activated osteoclasts rather than directly by carcinoma. Tumor necrosis factors - receptor activator of NF-kB (RANK), receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) - play an important role in osteoclastogenesis. According to histological point of view, there are three patterns of bone invasion - erosive, mixed and infiltrative. The most commonly used imaging techniques when evaluating bone invasion by oral squamous cell carcinoma include CT and MRI.This review is focused on the cellular and molecular mechanisms, histological patterns and detection methods of bone invasion caused by oral squamous cell carcinoma.