Primordial Odontogenic Tumor of the Maxilla Mimicking Odontogenic Myxoma in a Child: A Case Report and Review of the Literature

Introduction: Primordial odontogenic tumor (POT) is an exceptionally rare benign mixed odontogenic neoplasm recognized as a distinct entity in the 2017 World Health Organization classification of head and neck tumors. Owing to its rarity and overlapping clinicopathological features with other odontogenic lesions, establishing the diagnosis before definitive treatment remains challenging. Case Report: We report the case of a 2-year and 10-month-old boy presenting with rapidly progressive swelling of the left maxilla associated with facial asymmetry and orbital displacement. An initial incisional biopsy performed at another institution suggested odontogenic myxoma. Computed tomography and magnetic resonance imaging demonstrated a large, well-defined expansile lesion occupying the left maxillary sinus with extensive bone thinning, cortical perforation and compression of the orbital contents. Because of the extent of the lesion, ocular involvement, and the presumed diagnosis, subtotal maxillectomy was performed, followed by immediate soft tissue reconstruction using an anterolateral thigh free flap and reconstruction of the orbital floor with a titanium plate. Histopathological examination of the entire surgical specimen established the final diagnosis of primordial odontogenic tumor. At 24 months of follow-up, no evidence of recurrence was observed, and visual function remained normal. Conclusions: The mean age at diagnosis is approximately 11 years. Cases of POT previously described in the literature were lesions ranging in size from 0.8 × 0.8 × 0.8 cm to 9.0 × 7.0 cm. Most lesions occurred in the posterior mandible and were described as well-defined and unilocular, and an association with an unerupted tooth was reported in all 39 cases (100%). This case illustrates the diagnostic limitations of incisional biopsy in biphasic odontogenic tumors and highlights the importance of integrating clinical, radiological, and histopathological findings. Although POT generally demonstrates benign biological behavior, extensive lesions involving critical anatomical structures may require individualized surgical management.