Not the Neck-tar of the Gods

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Chin lesion

For 4 years, the lesion on this 66-year-old woman’s chin has been growing slowly, causing little or no pain. However, a foul-smelling cloudy liquid drains from the site about once a week and—understandably—causes her considerable distress. Her primary care provider (PCP) regarded the problem as an infection and prescribed an antibiotic, which reduced the lesion’s size for a time. However, it soon grew again after the patient completed the treatment.

The patient denies any other serious health conditions such as diabetes or immunosuppression. She states she never had an injury to this area. Concerned about the possibility of skin cancer, the PCP refers the patient to dermatology.

Physical exam reveals a patient in no particular distress, afebrile, and oriented in all 3 spheres. She is cooperative with the history and exam. Her husband, who has accompanied her, helps to corroborate her answers.

The lesion is striking both in size (2.8 cm) and mixed morphology. A deeply retracted 1.5-cm dimple is located on the right lower chin/submental interface, situated evenly with the right lateral oral commissure. There is no erythema in this area or elsewhere in or around the lesion.

A fleshy, vermicular, 2 × 4–mm, soft, friable linear mass protrudes from the dimple, extending toward the submental region. Gentle pressure produces a small amount of pustular material issuing from the center of the retracted area. There are no other nodes in the region. There is little or no evidence of past overexposure to ultraviolet sources (dyschromia, weathering, actinic keratoses, or telangiectasias).

Given the signs and location of the lesion, the most likely diagnosis is

Thyroglossal duct cyst

Branchial cleft cyst

Squamous cell carcinoma

Cutaneous sinus tract of odontogenic origin


The correct answer is cutaneous sinus tract of odontogenic origin (choice “d”).


These uncommon lesions are known by several names, including odontogenic fistula. Invariably, they are misdiagnosed as an “infection” and treated with antibiotics, which only calm these lesions until they inevitably return to their pretreatment appearance. Though bacteria (mostly Peptostreptococcus—the anaerobe predominating in the mouth) are involved, this is not an infection as it usually manifests.

The underlying process of this condition is caused by a periapical abscess: as it grows in size and pressure, it enters into the mouth or fistulizes out through the buccal tissue, continuing until it penetrates the skin and begins to release its pustular contents. Eighty percent manifest on the submental or chin area, while 20% tunnel inwards toward the oral cavity.

They initially manifest as papules with a 2-to-3-mm surface that soon drain pus from a central sinus. As this continues, the epithelium responds to the chronic inflammation by forming a mass of pseudoepitheliomatous hyperplasia. Biopsy would reveal that the mass also shows signs of chronic inflammation. Ordinary bacterial culture often shows nothing because the predominant organism is an anaerobe. At most, one might see a polymicrobial result.


For affected patients, a dentist can be considered for radiography of the area to confirm the location of the periapical abscess. Then the tooth is usually extracted, resulting in a cure. No further treatment of the sinus tract is necessary because it will essentially disappear over time. The tract does not require excision because it is lined with reactive granulation tissue and not epithelium (as is the case for many other fistular processes).

If the dental exam and radiograph fail to show the expected result, the other diagnoses—thyroglossal duct cyst, branchial cleft cyst, squamous cell carcinoma—would have to be considered.

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