Introduction:Pre-auricular sinus (PAS) is a commoncongenital anomaly in children which was first described in 1864 by Heusinger.1mostly it presents in front ofthe auricle without any diagnostic dilemma. But confusion arises when itpresents with post-auricular swelling, abscess or discharging sinus.2The vast majority of PAS are asymptomatic and do not require treatment.However, in post-auricular variety, surgical excision is recommended becausethe likelihood of recurrent infections is high.2 Simple excision ofthe sinus is not sufficient in these cases.
It requires bi-directional approachfrom both pre and post-auricular sides.3 Here we describe series of pre-auricularsinus with post-auricular extension, a “variant type” of pre-auricular sinusand their management. Materialsand methods: A prospective study was done in thedepartment of ENT in a tertiary care hospital of West Bengal from April 2014 toMarch 2017. In this period total 82 cases of pre-auricular sinus were treated.Among them six patients were lost in follow up. So we excluded them from ourstudy. Among 76 patients, seven patients had pre-auricular sinus withpost-auricular extension. History of swelling and discharge behind the ear, hearingloss and ear discharge, previous surgery or any systemic disease were taken.
Thorough examination of pinna, pre and post auricular region, external auditorycanal and tympanic membrane were done. Audiological tests and X-ray bothmastoids lateral oblique view were done. Patients with post-auricular abscessor perichondritis were treated with broad spectrum antibiotics and analgesics. Aftercontrol of infection and proper pre-operative investigations patients wereposted for operation under general anaesthesia. Local infiltration with 2% lignocaineand 1:2,00,000 adrenaline was done into both pre and post auricular incisionlines. Diluted methylene blue was injected in the pre-auricular opening.
Ellipticalincision was given around both pre-auricular pit and post-auricular scar. Sharpdissection was done from both pre and post auricular sides till the blue linedtract was visualized. The tract was followed and seen extending through theconchal cartilage. The sinus tract along with a thin rim of conchal cartilageand pre and post-auricular cuff of skin was excised in toto. Wound was closedand mastoid bandage was given. Post-operative period was uneventful in allcases. Stitches were removed after one week. Patients were followed up for aminimum of one year.
Results:In this study, there were seven cases of”variant type” of pre-auricular sinus among total 76 cases of pre-auricularsinus. There were five males and two females in the variant group. Among themsix patients were in the first decade of life and one patient was in the seconddecade of life. There was history of incision and drainage for post-auricularabscess in three patients. Five of them had lesion on right side and two had onleft side. Four patients presented with post-auricular scar, two patientspresented with post-auricular discharging sinus and one patient presented withpost-auricular abscess.
All of them had pre-auricular pit on the ascending limbof helix. Wound healing was perfectly normal in all patients. None hadrecurrence till one year follow up. Discussion:Pre-auricular sinus (PAS) is the mostcommon variant of all peri-auricular cysts, fistulas, and sinuses.4 Thepinna is formed by mesoderm and ectoderm from the first and second branchialarches and first branchial cleft. During the sixth week of embryonic development,mesenchymal proliferation produces the six hillocks of His. Three hillocksgather on the caudal aspect of the first branchial arch, and another three onthe cephalic aspect of the second branchial arch. The hillocks eventuallyenlarge and fuse to form the pinna.
With growth of the auricle, thecontribution of the first branchial arch becomes relatively reduced.5The exact embryologic basis of pre-auricular sinuses is uncertain. They may berelated to an incomplete fusion of the first arch hillocks, an entrapment ofectodermal folds during auricular formation, or a defective closure of thedorsal portion of the first branchial cleft.5It has an estimated incidence of 0.1 to10% with higher incidence among Asians and Africans.6 Fifty percentcases of PAS are unilateral, occur sporadically and are on right side.
7Bilateral cases are usually inherited and the pattern is of autosomal dominantwith reduced penetrance and is linked to chromosome 8q11.1 to q13.3.8PAS may also be related to branchiogenic fistulas, hearing loss and renalmalformations.2 The cutaneous pit of the pre-auricularsinus is most often located on or near the ascending limb of the helix but canalso open along the postero-superior margin of the helix as well as the tragusand lobule.9 While both cutaneous opening and fistulous tracts areclassically located anterior to the external auditory canal, a reported”variant type” has its opening behind an imaginary vertical line drawn at theposterior most aspect of the tragus and the posterior aspect of the ascendinglimb of the helix.3 Choi et al.
reported that the “variant type” ofpre-auricular sinus comprised 10.9% of pre-auricular sinus, that all fistulaswere located on the ascending helix, and that the fistulous tract was directedposteroinferiorly.3 In this study, the variant group was 9.21%(7/76) of all patients, which is similar to Choi et al. This “variant type” typicallypresents with post-auricular swelling which may be confused with otherpathology like post-auricular lymphadenitis, sebaceous cyst, dermoid cyst,mastoid abscess, perichondritis.10,11 The principles of treatment of PAS are completeexcision of the pit, sinus and sac during the period of quiescence aftertreating active infection with culture and sensitivity based antibiotics.2Various techniques of excision of classical PAS include simple sinectomyapproach, supra-auricular approach, facelift approach and inside out approach.12,13,14PAS is notorious for recurrence due to difficult identification of multipleramifications, scarring and fibrosis, as well as their close proximity toperichondrium.
11 In the present case series, we faced with theproblem of how to approach surgically. If the exposure is via classicalpre-auricular approach, then we would risk recurrence by leaving behind bits ofthe sinus tract. Since the pinna receives majority of its blood supply fromanterior auricular artery (branch of auriculotemporal artery), superiorauricular artery (branch of middle temporal artety), and posterior auricularartery; there is risk of devascularisation of the pinna with extendedsupra-auricular approach.15 The facelift incision would needextensive dissection inferior to the external auditory canal and havedifficulty in exposing the tissue superior to external auditory canal.16The post-auricular incision is a familiar one often used for approaching themiddle ear.
It preserves anterior auricular vessels and superior auricularvessels saving the surgeon from the anxiety of leaving behind a devascularizedpinna.17 In the present case series, we used bi-directionalapproach, which included pre and post auricular incisions with cuff of skin aroundthe puncta or scar. This gave adequate exposure to the entire lesion frompost-auricular groove to temporalis fascia antero-superiorly. Post-operativecosmesis was improved since the incision was in the post-auricular groove in atension free region.
The pre-auricular incision was small and hidden in theskin crease. Conclusion:Pre-auricular sinus may present as”variant type” with post-auricular abscess or discharging sinus. So when apatient present with post-auricular abscess or discharging sinus, pre-auricularregion and pinna should be examined carefully. This helps to avoid unnecessaryinvestigations and interventions which only complicate future management ofthese patients.