Background: Adenocarcinoma arising from an inverted schneiderian papilloma originating in the frontal sinus is rare.
Methods: The patient presented with right eye proptosis, hyposmia, bilateral nasal congestion. CT scan, MRI, and endoscopic biopsy of a mass was performed, finding adenocarcinoma. Anterior craniofacial resection, right orbital exenteration, right neck dissection and right anterolateral thigh free flap reconstruction was performed.
Results: Inverted Schneiderian papillomas can transform into squamous cell carcinoma. They uncommonly originate in the frontal sinus, or for them to transform into adenocarcinoma. Both benign and malignant inverted papillomas have the potential to be locally invasive, so in patients presenting with the non-specific clinical features associated with inverted papillomas, a high clinical index of suspicion must be maintained.