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What are the causes of ear malformations?

In most cases, the path opens to a small hole just in front of the ear, but it can appear in other locations less frequently. The depth is variable and it can present unilaterally or bilaterally. 

This was explained by Dr. Lissette Cheas Bidó, otorhinolaryngologist from the Centers for Advanced Medicine Diagnosis and Medical Conferences and Telemedicine (CEDIMAT).

The cause of ear malformations?

Children are born with this malformation that is closely related to the embryology of the ear, it forms between the fourth and eighth week of embryonic development in the first and second branchial arches, explains the expert

Preauricular fistulas are considered to be formed by entrapment of ectoderm, in the thickness of the mesoderm, during the development of the auricle. This malformation is not associated with hearing problems and is rarely associated with genetic syndromes involving other organs. 

External ear malformations occur in less than 1% of healthy children. It is considered a common birth defect even though its incidence may sound low. This problem occurs in both genders, males and females equally. This malformation is not necessarily hereditary, however, when it occurs bilaterally, family history is more frequent. 

Preauricular fistulas are usually sporadic, although one-third of cases are familial. About 50% of cases are bilateral; however, most cases are asymptomatic. Only a third of patients are aware that they have this type of malformation, says the specialist.

Many times, patients do not perceive that they have this type of injury and it is not until adult life that they become aware of the presence of the malformation, most of the time due to infection or sebaceous content leakage. 

Once the lesions become evident, patients usually take a few years to see a doctor and this is because preauricular fistulas are usually asymptomatic at first, indicates the CEDIMAT doctor.

Manifestations can be chronic and intermittent, with drainage of purulent material through the dimple opening, which predisposes to infection and, on some occasions, to abscess formation.

Once the infection has occurred, recurrent symptoms occur and can be complicated by facial cellulitis or ulcerations near the ear.

Its discharge consists of dry cheese-like material, and when the fistula is complicated by infection, Staphylococcus is commonly isolated, and less frequently, Streptococcus, Proteus, and Peptococcus species.

Signs and symptoms

The most frequent manifestations are:

  • Small hole visible in front of one or both ears.
  • Swelling, pain, fever, redness, or pus in or around the hole, pointing to an infection, such as cellulitis or an abscess.
  • A slow-growing mass right next to the hole, which we associate with a cyst. The cyst increases the possibility of infection.

One of the main manifestations of preauricular fistulas is that they can form benign cysts or become infected and form abscesses. In those cases where patients present infectious symptoms recurrently, it is recommended to be surgically removed. 


If the fistula does not present infectious episodes, no treatment is necessary. In cases of infection, the use of antibiotics and analgesics is recommended. Sometimes it is necessary to drain the fistulas if they have abscesses that do not resolve with the use of antibiotics.

The definitive treatment for preauricular fistulas is the surgical removal of their entire length. Most of the time the surgery is done on an outpatient basis.

Surgical resection should be avoided during acute inflammatory episodes to prevent recurrence of the malformation. In these cases, it is preferable to improve the acute condition with the use of oral antibiotics and anti-inflammatories and then plan the surgery. 

In cases where there is an infection, it will be necessary to administer broad-spectrum antibiotics orally, as well as apply hot compresses to accelerate the healing of the inflammatory process and some local topical cream against staphylococci.

Some clinicians limit surgery to patients with a previous infectious episode because once the fistula becomes infected it rarely remains asymptomatic; reinfection is the constant in these cases. There are also doctors who, even in asymptomatic patients, indicate surgical intervention. Recurrence rates after surgical treatment have been reported between 13 and 42%.

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