Sinonasal ameloblastoma: A case report focusing on histogenesis and related morphological characteristics

Abstract Sinonasal ameloblastoma is an extremely rare neoplasm. Herein we present a case of sinonasal ameloblastoma and discuss its histogenesis and related morphological characteristics. An 80 years-old Japanese male had a polypoid mass initially diagnosed as a nasal polyp. A prior biopsy was interpreted as a salivary gland-type tumor and he was therefore referred to a regional general hospital for surgical removal of the lesion. Preoperative contrast-enhanced magnetic resonance imaging revealed a space-occupying lesion in the right nasal cavity and the right maxillary sinus with poor contrast enhancement. Histopathological findings revealed that the tumor consisted of follicular/plexiform-like cell nests with peripheral palisading, extending continuously to the adjacent mucosa. A recurrent polypoid mass accompanied by bone destruction of the maxillary sinus was found two years after the surgery, but it was left untreated. Although sinonasal ameloblastoma remains under-recognized, its characteristics, including its histopathological features, need to be more widely known to allow its correct diagnosis and adequate management.