Deep frontotemporal dermoid cyst presenting as a discharging sinus: a case report and review of literature

The commonest location for dermoid cysts in the head and neck is at the frontotemporal or brow region. They usually present as discrete slow growing masses located superficially at the angle of the brow. The presentation as a discharging sinus in the frontotemporal region is rare. In contrast, it is common for nasal dermoids to present as sinuses or fistulae (10-45%) and with a tract extending deep to involve the underlying bone or intracranium. In view of their differences in presentation, preoperative CT scans are generally recommended for the nasal dermoids but not for the frontotemporal dermoids. We report a rare case of a deep frontotemporal dermoid cyst presenting as a discharging sinus at the right temporal region in a girl aged 2 years and 6 months. It had a sinus tract extending deep to form an intraosseous cyst in the frontal and sphenoid bone. The base of the cyst was attached to the dura of the middle cranial fossa. Only a few similar cases were reported in the literature. In the light of our experience with this case, we recommend that this rare type of frontotemporal cyst sinus be operated only after a CT or MRI scan.