[Computed tomography image analysis of peritonsillar abscess]

The peritonsillar abscess (PTA) is one of the most common infectious diseases in the head and neck area and is treated with puncture, incision, or abscess tonsillectomy. In the present study, we performed a retrospective study for the patients who were diagnosed as having PTA on the basis of CT findings at the Kagoshima University Hospital between January 2007 and April 2012. The clinical characteristics were compared with the CT images and the indication of abscess tonsillectomy was discussed. In total, 145 patients (152 sides), mean age of 41 years (range: 5-80 years) were enrolled in the study. Patients having any surgical treatment such as puncture and incision before visiting our hospital were excluded. The CT findings revealed that PTA could be classified into two categories by the shapes of the abscess: the Oval type and Cap type. Further, the location of the abscess was differentiated superior and inferior, and classified into 4 categories: superior Oval type, superior Cap type, inferior Oval type, and inferior Cap type. The results showed that the number of the superior Oval type PTA was largest and followed by superior Cap type, inferior Cap type, and inferior Oval type in this order. When the CT classifications were compared with clinical findings, patients with the inferior Cap type abscess had laryngeal edema and airway obstruction more frequently than the other categories of PTA. Histological examination of the specimens obtained during surgery showed that the Cap type abscess tended to include more muscular tissue compared to the Oval type, indicating that inflammation might be more severe and wider in the Cap type than the Oval type. Those findings suggest that the inferior Cap type of PTAs need more intensive and reliable treatments such as abscess tonsillectomy.