QUIZ: No. 7, 01/03/2026

Diagnosis: Odontogenic Cutaneous Fistula with Chronic Mandibular Osteomyelitis

Findings: Radiograph of the mandible demonstrates a periapical radiolucency involving the left mandibular molar with loss of lamina dura. CT images show cortical breach along the buccal cortex. There is adjacent reactive sclerosis and thickening of the mandible. A linear hypodense sinus tract extends from the periapical region through the soft tissues into the submandibular region reaching the skin surface. No aggressive periosteal reaction or destructive bone lesion is seen. MRI demonstrates a T2 hyperintense sinus tract extending from the mandibular periapical region to the skin surface with surrounding inflammatory changes.

Discussion

Ø  Odontogenic cutaneous fistula is a chronic draining sinus resulting from periapical dental infection. The infection spreads from the pulp to the periapical region, perforates the cortical bone, and tracks along the path of least resistance into the soft tissues, forming an extraoral sinus.

Ø  Mandibular molars commonly drain into the submandibular or submental region.

Ø  Dental caries à  pulpitis à periapical abscess à Infection tracks along path of least resistance à Penetrates cortical bone à Forms extraoral draining sinus

Ø  Management: Definitive treatment is elimination of the dental source by endodontic therapy or extraction, along with antibiotics. The sinus tract usually resolves spontaneously once the source is treated.

Ø  Because the cutaneous opening may be distant from the dental source, it is often misdiagnosed. Imaging is key in identifying the dental origin and associated osteomyelitic changes.

Teaching pearl:

Ø  Any chronic discharging sinus in the lower face or upper neck region in a child should raise suspicion of a dental origin.

Ø  Failure to recognize the dental source may lead to unnecessary surgical procedures.

Ø  Demonstration of a periapical lucency with a sinus tract extending to the skin confirms odontogenic cutaneous fistula.

P.S – In this case, there was a history of dental filling 5 months prior to presentation.