Carolyn Eaton, Chang Bon Man, Jaimini Mehta, Chi-Wa Chan
Osteomyelitis with bony sequestra in the mandible can be seen secondary to dental infections and mandibular fractures. It is unreported that a case of osteomyelitis secondary to pericoronitis should present as a parotid mass. A 34 year old man presented to our emergency department with a painful right parotid mass and history of recurrent pericoronitis. Initially diagnosed as parotitis with a differential including parotid tumour, an ultrasound scan showed a 5.2cm x 3.2cm hypoechoeic mass warranting further investigation. Subsequent MRI and CT scans confirmed this not as a tumour but osteomyelitis with bony sequestra of the right mandibular ramus. A sinus was seen to extend from the lower right third molar through bone and parotid gland into subcutaneous tissue. He underwent surgical debridement of the bony sequestra, extraction of the offending tooth and an extended course of antibiotics.
Parotid masses are a common presentation for salivary tumours however pathology of surrounding tissue must be excluded. Ling et al. reported 3 cases of chronic osteomyelitis masquerading as parotid tumours resulting in parotidectomy due to misdiagnosis. The diagnosis in our case was reached with a strong index of suspicion and adequate three dimensional imaging. This allows for surgical planning and effective treatment. Establising causes of parotid swellings can be initially difficult and masses thought to be within parotid tissue can be misdiagnosed on clinical examination and ultrasound imaging. A detailed history and three dimensional imaging can often elucidate the diagnosis even when the cause is unusual.