Introduction: post-auricular sides.3 Here we describe series

Introduction:

Pre-auricular sinus (PAS) is a common
congenital anomaly in children which was first described in 1864 by Heusinger.1
mostly it presents in front of
the auricle without any diagnostic dilemma. But confusion arises when it
presents with post-auricular swelling, abscess or discharging sinus.2
The vast majority of PAS are asymptomatic and do not require treatment.
However, in post-auricular variety, surgical excision is recommended because
the likelihood of recurrent infections is high.2 Simple excision of
the sinus is not sufficient in these cases. It requires bi-directional approach
from both pre and post-auricular sides.3 Here we describe series of pre-auricular
sinus with post-auricular extension, a “variant type” of pre-auricular sinus
and their management.   

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Materials
and methods:

A prospective study was done in the
department of ENT in a tertiary care hospital of West Bengal from April 2014 to
March 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 our
study. Among 76 patients, seven patients had pre-auricular sinus with
post-auricular extension. History of swelling and discharge behind the ear, hearing
loss and ear discharge, previous surgery or any systemic disease were taken.
Thorough examination of pinna, pre and post auricular region, external auditory
canal and tympanic membrane were done. Audiological tests and X-ray both
mastoids lateral oblique view were done. Patients with post-auricular abscess
or perichondritis were treated with broad spectrum antibiotics and analgesics. After
control of infection and proper pre-operative investigations patients were
posted for operation under general anaesthesia. Local infiltration with 2% lignocaine
and 1:2,00,000 adrenaline was done into both pre and post auricular incision
lines. Diluted methylene blue was injected in the pre-auricular opening. Elliptical
incision was given around both pre-auricular pit and post-auricular scar. Sharp
dissection was done from both pre and post auricular sides till the blue lined
tract was visualized. The tract was followed and seen extending through the
conchal cartilage. The sinus tract along with a thin rim of conchal cartilage
and pre and post-auricular cuff of skin was excised in toto. Wound was closed
and mastoid bandage was given. Post-operative period was uneventful in all
cases. Stitches were removed after one week. Patients were followed up for a
minimum of one year.

 

Results:

In this study, there were seven cases of
“variant type” of pre-auricular sinus among total 76 cases of pre-auricular
sinus. There were five males and two females in the variant group. Among them
six patients were in the first decade of life and one patient was in the second
decade of life. There was history of incision and drainage for post-auricular
abscess in three patients. Five of them had lesion on right side and two had on
left side. Four patients presented with post-auricular scar, two patients
presented with post-auricular discharging sinus and one patient presented with
post-auricular abscess. All of them had pre-auricular pit on the ascending limb
of helix. Wound healing was perfectly normal in all patients. None had
recurrence till one year follow up.  Discussion:
Pre-auricular sinus (PAS) is the most
common variant of all peri-auricular cysts, fistulas, and sinuses.4 The
pinna is formed by mesoderm and ectoderm from the first and second branchial
arches and first branchial cleft. During the sixth week of embryonic development,
mesenchymal proliferation produces the six hillocks of His. Three hillocks
gather on the caudal aspect of the first branchial arch, and another three on
the cephalic aspect of the second branchial arch. The hillocks eventually
enlarge and fuse to form the pinna. With growth of the auricle, the
contribution of the first branchial arch becomes relatively reduced.5
The exact embryologic basis of pre-auricular sinuses is uncertain. They may be
related to an incomplete fusion of the first arch hillocks, an entrapment of
ectodermal folds during auricular formation, or a defective closure of the
dorsal portion of the first branchial cleft.5It has an estimated incidence of 0.1 to
10% with higher incidence among Asians and Africans.6 Fifty percent
cases of PAS are unilateral, occur sporadically and are on right side.7
Bilateral cases are usually inherited and the pattern is of autosomal dominant
with reduced penetrance and is linked to chromosome 8q11.1 to q13.3.8
PAS may also be related to branchiogenic fistulas, hearing loss and renal
malformations.2 The cutaneous pit of the pre-auricular
sinus is most often located on or near the ascending limb of the helix but can
also open along the postero-superior margin of the helix as well as the tragus
and lobule.9 While both cutaneous opening and fistulous tracts are
classically located anterior to the external auditory canal, a reported
“variant type” has its opening behind an imaginary vertical line drawn at the
posterior most aspect of the tragus and the posterior aspect of the ascending
limb of the helix.3 Choi et al. reported that the “variant type” of
pre-auricular sinus comprised 10.9% of pre-auricular sinus, that all fistulas
were located on the ascending helix, and that the fistulous tract was directed
posteroinferiorly.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” typically
presents with post-auricular swelling which may be confused with other
pathology like post-auricular lymphadenitis, sebaceous cyst, dermoid cyst,
mastoid abscess, perichondritis.10,11 The principles of treatment of PAS are complete
excision of the pit, sinus and sac during the period of quiescence after
treating active infection with culture and sensitivity based antibiotics.2
Various techniques of excision of classical PAS include simple sinectomy
approach, supra-auricular approach, facelift approach and inside out approach.12,13,14
PAS is notorious for recurrence due to difficult identification of multiple
ramifications, scarring and fibrosis, as well as their close proximity to
perichondrium.11 In the present case series, we faced with the
problem of how to approach surgically. If the exposure is via classical
pre-auricular approach, then we would risk recurrence by leaving behind bits of
the sinus tract. Since the pinna receives majority of its blood supply from
anterior auricular artery (branch of auriculotemporal artery), superior
auricular artery (branch of middle temporal artety), and posterior auricular
artery; there is risk of devascularisation of the pinna with extended
supra-auricular approach.15 The facelift incision would need
extensive dissection inferior to the external auditory canal and have
difficulty in exposing the tissue superior to external auditory canal.16
The post-auricular incision is a familiar one often used for approaching the
middle ear. It preserves anterior auricular vessels and superior auricular
vessels saving the surgeon from the anxiety of leaving behind a devascularized
pinna.17 In the present case series, we used bi-directional
approach, which included pre and post auricular incisions with cuff of skin around
the puncta or scar. This gave adequate exposure to the entire lesion from
post-auricular groove to temporalis fascia antero-superiorly. Post-operative
cosmesis was improved since the incision was in the post-auricular groove in a
tension free region. The pre-auricular incision was small and hidden in the
skin crease.  Conclusion:

Pre-auricular sinus may present as
“variant type” with post-auricular abscess or discharging sinus. So when a
patient present with post-auricular abscess or discharging sinus, pre-auricular
region and pinna should be examined carefully. This helps to avoid unnecessary
investigations and interventions which only complicate future management of
these patients.