Congenital Aural Fistula Developing Between the Third and Fourth Hillocks of the Embryonal Helix and Presenting a Large Temporal Mass: A Case Report.

This report aimed to introduce a very rare presentation of congenital aural fistula and its treatment. A 13-year-old girl presented with a mass on the right temporal region with protrusion of the helix. She noticed a mass a month previously, and the mass gradually swelled with pain. Pus discharged from the pit behind the helix. Mastoiditis was suspected; however, the tympanic membrane was normal. Magnetic resonance imaging revealed a cystic mass in the temporal region. The surgical removal of the mass was performed using a postauricular incision. The mass was cystic and had a stem connected to the pit. Insertion of a probe into the pit showed a connection to the mass. The mass was totally removed with the skin around the pit. Histologically, the cyst connected to the fistula and its lumen was covered with squamous cells. A diagnosis of a congenital aural fistula developed posterior to the helix was made. Considering its location, the fistula had been formed between the third and fourth hillocks of the embryonal helix. Aural fistula developed posteriorly is very rare, and it mimicked a temporal tumor or mastoiditis with a protruding auricle. Careful observation of the skin and consideration from developmental aspects are needed for an accurate diagnosis.