An unusual biphasic pulmonary lesion: late metastasis from a mandibular ameloblastoma

Abstract

Ameloblastoma is mostly a benign odontogenic tumour most frequently arising within the mandible and maxilla. Although ameloblastoma can be locally aggressive and prone to local recurrence, metastasis is a rare (and usually late) complication. We report a case of a metastatic ameloblastoma to the lung following an original presentation with a traumatic jaw fracture through what was thought to be a mandibular odontogenic cyst in 1988. The definitive diagnosis of ameloblastoma was not reached until a local recurrence occurred ten years later; this was managed with hemimandibulectomy and post-operative radiotherapy. A single lung lesion was identified incidentally 33 years after the original presentation: it demonstrated typical morphological features of ameloblastoma and FOXP1 immunostaining was confirmatory. Recent advances in understanding the genetic pathogenesis of ameloblastoma demonstrate frequent BRAFV600E mutations as well as mutations in other MAP kinase pathway genes such as KRAS, NRAS, HRAS and FGFR2.1 Several case reports have indicated promising results with BRAF inhibitor therapy in metastatic ameloblastoma.2 1.Brown N, Betz B. Ameloblastoma: a review of recent molecular pathogenetic discoveries. Biomark Cancer 2015; 7 (Suppl 2): 19–24.2.González-González R, López-Verdín S, Lavalle-Carrasco J, et al. Current concepts in ameloblastoma-targeted therapies in B-raf proto-oncogene serine/threonine kinase V600E mutation: Systematic review. World J Clin Oncol 2020; 11: 31–42.