Background: Local recurrence, and regional and distant metastases, respectively, develop in 30% and 15% of patients with esthesioneuroblastoma (ENB).

Methods: This case report includes 3 patients with unusual recurrences of ENB in the sinonasal tract.

Results: Patient 1 developed ENB in the bilateral maxillary sinuses after unilateral endoscopic resection of a left ENB followed by postoperative proton radiotherapy. Patient 2 developed ENB at the left optic-carotid recess 7 years after a craniofacial resection and postoperative radiotherapy. Patient 3 developed ENB over the left zygomatic process of the maxilla 4 years after a cranioendoscopic resection and postoperative radiation therapy for ENB of the ethmoid sinuses with intracranial extension. The possibility of venous tumor emboli must be considered as a likely etiology. However, alternative explanations include the development of a second primary or potential transformation because of tumor signaling.

Conclusions: We present 3 cases that may represent metastasis of ENB within the sinonasal tract.