Lingual tonsillolith: prevalence and imaging characteristics evaluated on 2244 pairs of panoramic radiographs and CT images.

OBJECTIVES: Lingual tonsilloliths are not as well-known to radiologists than palatine tonsilloliths, although they might be common in clinical practice. The aim of this investigation was to clarify the prevalence and imaging characteristics of lingual tonsilloliths using panoramic radiographs and CT images. METHODS: This study included 2244 patients without pathology at the base of tongue who had undergone panoramic radiography and CT of the maxillofacial region. The size, number and position of lingual tonsilloliths relative to the mandible and tongue were evaluated. RESULTS: Lingual tonsilloliths were observed in 33 (1.5%) and 108 (4.8%) of all patients on panoramic radiographs and CT images, respectively. The prevalence was higher in patients aged ≥40 years than in those aged < 40 years (χ2, p < 0.01). They appeared as small, round- or rod-shaped calcified bodies, and they always located closely anterior (1-17 mm) to the anterior border of oropharyngeal airway on panoramic radiographs. Lingual tonsilloliths were superimposed over the surrounding soft tissue inferior to the body of the mandible, posteroinferior to the angle of the mandible and posterior to the mandible in 16 (48.5%), 15 (45.5%) and 1 (3.0%) individual, respectively. A significant correlation was observed between the detectability on panoramic radiographs and size (Spearman's r = 0.961, p < 0.01) of tonsilloliths, as revealed by CT images. CONCLUSION: Lingual tonsilloliths commonly appear on CT. They also appear on panoramic radiography and may superimpose the surrounding soft tissue of the mandible. Although lingual tonsilloliths may resemble other pathological calcifications including submandibular sialoliths and lingual osseous cholistoma, they can be differentiated by carefully observing panoramic radiographs. When clinicians detect calcified bodies near the base of tongue, lingual tonsilloliths should be included in the differential diagnoses.