Differences between radioactive iodine-induced sialadenitis and chronic obstructive parotitis

The purpose of this study was to clarify the differences in the diagnosis and treatment outcomes between radioactive iodine-induced sialadenitis (RAIS) and chronic obstructive parotitis (COP). The study cohort comprised 47 consecutive patients diagnosed with RAIS and 50 patients with COP. All patients were treated by interventional endoscopy. Clinical, sialography, and endoscopy characteristics and treatment outcomes were compared between the two groups. Compared with the COP group, the RAIS group included more females (male:female ratio 1:8.4 vs 1:2.1; P = 0.011) and had a younger onset age (42 vs 50 years; P = 0.001) and shorter disease duration prior to hospital visit (5.4 vs 34.8 months; P < 0.001). In the RAIS group, sialography revealed obliteration of the main duct (20.4% vs 0%; P < 0.001), non-visualization of the main gland (23.7% vs 0%; P < 0.001), and incomplete contrast filling of the main gland (19.4% vs 6.4%; P = 0.008), which were scarcely observed in the COP group. Endoscopy revealed a higher percentage of duct atresia in RAIS compared to COP (20.4% vs 0%; P < 0.001). During follow-up, a higher percentage of RAIS patients had duct atresia and gland atrophy (49.5% vs 1.1%, P < 0.001). Compared with COP, RAIS more commonly involves younger females and has a shorter disease duration. Atresia of the main duct and atrophy of the gland parenchyma occur more often despite the use of interventional endoscopy.