An unusual clinical and histopathologic presentation of a maxillofacial ameloblastoma: a literature review and case report.

The objectives of this article are to describe an unusual clinical and histopathologic presentation of an ameloblastoma affecting the right maxilla, maxillary sinus, and nasal cavity and to discuss the difficulty of establishing a clinical classification based on the most recent edition of Head and Neck Tumours in the WHO Classification of Tumours series (2022). A 74-year-old man presented with a 6 × 6-cm expansile, ulcerated mass on the right lateral palate. A clinical diagnosis of squamous cell carcinoma was rendered. A biopsy was performed, and the specimen showed multiple histologic patterns of ameloblastoma inconclusive of odontogenic or sinonasal origin. Cone beam computed tomographic imaging demonstrated a well-defined unilocular mass in the right maxilla extending up to the nasal cavity. A surgical resection was performed and confirmed the diagnosis of maxillary ameloblastoma with extension into the nasal cavity. This dilemma in delayed diagnosis led to a literature search for similar maxillary ameloblastoma cases with extension into vital structures. In 45 cases previously reported in the literature, the median age of patients with maxillary ameloblastoma was 50 years, and there was extensive involvement of adjacent vital structures. The nasal cavity/sinonasal region (24/45), orbit/orbital floor (12/45), multiple fossae (5/45), and base of the skull (4/45) were the most common extensions of maxillary ameloblastoma. Fifteen patients had lesions with multiple extensions, and 1 patient showed lung metastasis. The most common histologic presentation was the follicular pattern, followed by the plexiform pattern or mixed follicular and plexiform patterns. Surgical interventions were performed on most patients, with the majority undergoing maxillectomy. Differentiating primary sinonasal ameloblastoma from gnathic ameloblastoma with sinonasal extension is challenging, and this article discusses subtle radiographic criteria and symptoms that aid in the distinction of both types. The authors suggest that variants of maxillary ameloblastoma with extensive involvement of the sinonasal region, orbit, or base of the skull be classified with a clinical diagnosis of maxillofacial ameloblastoma, regardless of the tumor origin.