Clinical classification of peritonsillar abscess based on CT and indications for immediate abscess tonsillectomy

Abstract Objective To clarify indications for immediate abscess tonsillectomy (IAT) for peritonsillar abscess (PTA). Methods A retrospective study was performed on 99 patients who were diagnosed with PTA on the basis of computed tomography (CT). Based on CT findings, PTA patients were classified into two categories by abscess shape: Oval type and Cap type. Furthermore, abscess location was differentiated into superior and inferior, resulting in a final classification of 4 categories: superior Oval type; superior Cap type; inferior Oval type; and inferior Cap type. In addition, the proportion of PTA patients showing extraperitonsillar spread into parapharyngeal spaces in each category was examined. Results Superior Oval-type PTA was the most common. Thirteen patients showed extraperitonsillar spread. When CT classifications were compared with clinical findings, patients with inferior Cap-type abscess displayed extraperitonsillar spread more frequently than the other categories of PTA. In all 13 patients, the parapharyngeal space was involved. In addition, 3 patients displayed retropharyngeal space involvement. In all 13 cases, abscess remained above the hyoid bone. Conclusions Inferior Cap-type PTA may need more intensive and reliable treatment, such as IAT, which might be effective for PTA showing extraperitonsillar spread.