The Variant Type of Preauricular Sinus: Postauricular Sinus

Abstract

Preauricular sinuses (PAS) are common congenital malformations that usually occur at the anterior margin of the ascending limb of the helix, but the positions of PAS and directions on the fistular tracts are rarely posterior to the external auditory canal (EAC), which presents as a postauricular swelling. We named these cases as the variant type of PAS ('postauricular sinuses'), and compared their clinical manifestations with those of the classical type. A retrospective study. We retrospectively reviewed the charts of patients who had undergone preauricular fistulectomy from 2002 to 2006. These patients were then categorized into two groups according to the position of the preauricular sinus sac. The classical group was defined as the group of patients with sacs located on the (superior) anterior to the EAC, and the variant group as those whose sacs are located on the posterior site of the EAC. We analyzed the incidence, previous histories, clinical manifestations, recurrence rates, and surgical techniques of the variant type of preauricular sinuses and compared them with those of the classical type. Eleven (10.9%) of 101 patients were diagnosed with preauricular sinuses of the variant type. The male to female ratios of the classical and the variant groups were 44:46 and 7:4, respectively. The average age of the patients was approximately 11 to 13 years in both groups. All variant types of preauricular sinuses showed preauricular pits located posterior to the imaginary line that connects the tragus with the posterior margin of the ascending limb of the helix, unlike the classical type. Most (72.8%) of the fistular tracts of the variant type were directed in the posterior-middle direction from the pits. The variant types were operated with a dual approach using preauricular and retroauricular incisions, unlike the classical type, and the recurrence rate was 0% (compared with 2.2% in the classical type). Frequent postauricular infected swellings may indicate the presence of the variant type of preauricular sinuses. The variant type of preauricular sinuses presenting in the postauricular area were found to have an unusual location of the fistula pit that was positioned posterior to the imaginary tragal extended line. A comprehensive physical examination of the preauricular pits should be performed to avoid incomplete excision of the variant types.