Prevalence and imaging characteristics of palatine tonsilloliths evaluated on 2244 pairs of panoramic radiographs and CT images

Palatine tonsilloliths incidentally detected on diagnostic imaging should be differentiated from pathologic calcifications to enable correct diagnosis and treatment. The aim of this study is to clarify the prevalence and imaging characteristics of palatine tonsilloliths on panoramic radiographs. We retrospectively reviewed 2244 individuals who underwent pairs of consecutive panoramic radiography and computed tomography (CT) of the head and neck region. The imaging characteristics of palatine tonsilloliths on panoramic radiography were compared with the findings from CT, which was considered the gold standard. Tonsilloliths were detected in 300 (13.4 %) and 914 (40.7 %) of the 2244 individuals on panoramic radiographs and CT, respectively. On panoramic radiographs, tonsilloliths were superimposed over the ramus of the mandible at the level coincident with and inferior to the soft palate in 176 (7.8 %) and 90 (4.0 %) individuals, respectively. Tonsilloliths were also superimposed over the surrounding soft tissue inferior to the body of the mandible, postero-inferior to the angle of the mandible, and posterior to the ramus of the mandible in 33 (1.5 %), 26 (1.2 %), and 28 (1.3 %) individuals, respectively. A significant correlation was observed between the detectability on panoramic radiographs and the size (Spearman r = 1.000) and number (Spearman r = 0.991) of tonsilloliths, as revealed by CT images. The present results suggest that tonsilloliths are commonly detected on panoramic radiographs. Furthermore, they can be superimposed on both the mandible and the surrounding soft tissue. Clinicians should include tonsilloliths among the differential diagnoses when calcified bodies are detected on panoramic radiographs.