Sinonasal undifferentiated carcinoma originating from inverted papilloma: A case report.

RATIONALE: Sinonasal inverted papilloma (IP) is a locally aggressive tumor found in the schneiderian membrane, lining the nasal cavity and paranasal sinuses.

PATIENT CONCERNS: We report a case of a 63-year-old woman with undifferentiated carcinoma (UC) arising in an IP in the left maxillary sinus.

DIAGNOSES: The preoperative diagnosis was IP of the maxillary sinus.

INTERVENTIONS: We performed endoscopic medial maxillectomy to remove the remnant mass in the left maxillary sinus.

OUTCOMES: Histological examination of the specimen revealed typical area of IP and sinonasal UC.

LESSONS: Clinicians should consider sinonasal UC in the differential diagnosis of malignancy arising in the sinonasal IP.