A fistula is an abnormal pathway between two anatomic spaces or a pathway that leads from an internal cavity or organ to the surface of the body. A sinus tract is an abnormal channel that originates or ends in one opening. An orofacial fistula is a pathologic communication between the cutaneous surface of the face and the oral cavity.
In the literature, the terms fistulas and sinuses are often used interchangeably. Stedman’s Medical Dictionary defines a sinus as a fistula or tract leading to a suppurating cavity. Orofacial fistulas are not common, but intraoral sinus tracts due to dental infections are common. When infection or neoplasia is involved, immediate treatment is necessary. Dental infections, salivary gland lesions, neoplasms, and developmental lesions cause oral cutaneous fistulas, fistulas of the neck, and intraoral fistulas.
Chronic dental periapical infections or dentoalveolar abscesses cause the most common intraoral and extraoral fistulas. These dental periapical infections can lead to chronic osteomyelitis, cellulitis, and facial abscesses. Infection can spread to the skin if it is the path of least resistance. Fascial-plane infections, space infections, and osteomyelitis can cause cutaneous fistulas. Fascial-plane infections often begin as cellulitis and progress to fluctuant abscess formation. Compared with the other conditions, fluctuant abscess formation is more likely to result in cutaneous fistulas.
A cutaneous lesion such as a furuncle can be misdiagnosed as a sinus tract to the skin of the face. One case report
demonstrates this occurrence from a periapical infection from the right central mandibular incisor, which drained to the patient’s chin. Because the tooth could not be restored, it was extracted, which resolved the lesion.
Another case with cutaneous manifestations involved a 44-year-old woman with a draining lesion to the skin just lateral to the nasofacial sulcus. Oral antibiotics did not help resolve the lesion. The patient had poor dentition, and a panoramic radiograph showed 2 periapical radiolucencies of the maxillary right lateral incisor and canine. The teeth were extracted, which resolved the lesion. Sheehan et al
recommend a dental examination and radiographs to rule out infection of dental origin to the cutaneous face or neck.
For general information on dental infections, see Dental Infections in Emergency Medicine.