A case of cutaneous odontogenic sinus.

Despite the fact that cutaneous sinus tracts of odontogenic origin are well documented, the condition is still commonly misdiagnosed, because chronic periapical periodontitis may be asymptomatic and is rarely open to the skin. A 75-year-old Japanese woman presented to our clinic with the chief complaint of a left cheek skin lesion with mild pain. Physical examination revealed a subcutaneous nodule covered with erythematous skin on her left buccal region. Cultures from the subcutaneous nodule grew Bacteroides species and Peptostreptococcus micros but did not yield acid-fast bacilli, fungi, or Actinomyces. Stains of smeared pus showed a considerable number of Gram-negative rods. The histopathological examination revealed a focal abscess formation in the lower dermis and subcutaneous tissue. Dental evaluation, including an orthopantogram, showed a radiolucent alveolar area at the left lower first molar apex, suggesting a periapical abscess. Antibiotic therapy for three weeks associated with surgical root canal therapy eliminated the subcutaneous nodule. A high degree of suspicion is required to correctly diagnose a lower facial lesion as being of odontogenic origin, and prompt dental evaluation should be considered.