[Detachment and retraction of masticatory muscles from the jaw possibly transfers the residual tumor cells and causes extopic recurrence of ameloblastoma].

OBJECTIVE: To The purpose of this article was to report a series of patients with ectopic recurrence of ameloblastoma and reveal the possible mechanism of ectopic recurrence.

METHODS: To retrospectively review the medical records of ameloblastoma in twenty years of two hospitals and choose ectopic recurrent cases and analyse the possible factors related to ectopic recurrence of ameloblastoma.

RESULTS: 31 cases of recurrent ameloblastoma in twenty years medical records of two hospitals were found, 6 of which were ectopic recurrent cases and all the primary sites were located in the mandible. Patients with ectopic recurrent ameloblastoma exclusively underwent conservative initial surgical procedures (curettage and enucleation) and all the primary tumors involved the insertions of the masticatory muscles. The recurrent sites included temporal region. parotid gland, floor of mouth, ventral tongue and intracranial site. A specific muscle was related both to the primary sites and the recurrent regions.

CONCLUSION: The detachment and retraction of the masticatory muscles from the insertion of the jaw, which may transfer residual tumor cells from the insertion (the primary) to the initial point of the muscles, is the possible mechanism of ectopic recurrence of ameloblastoma.