Scintigraphic features of chronic sialadenitis and Sjögren's syndrome: a comparison

An abnormal salivary scintigram is an accepted objective criterion in the diagnosis of primary and secondary Sjögren's syndrome, an immune-mediated disorder characterized by xerostomia and kerato-conjunctivitis sicca. However, chronic sialadenitis constitutes a major differential diagnostic consideration in the xerostomic population. We investigated 39 cases of biopsy-confirmed chronic sialadenitis and 152 individuals with first- or second-degree Sjögren's syndrome, according to international classification criteria. We analysed scintigraphic defects in terms of glands per patient, distribution patterns, kinetics and severity. Relative to Sjögren's syndrome, chronic sialadenitis showed significantly fewer defective glands per patient, less frequent dual parotid-submandibular defects, fewer combined deficits of uptake and discharge, and milder uptake failure. No statistically significant differences were found in the frequency of single gland abnormality, predilection for submandibular involvement, and respective proportions of uptake-only and discharge-only defects. Unevaluable discharge due to low uptake, although comprising only 34% of test-positive cases, appeared to be a highly specific but insensitive scintigraphic marker for Sjögren's syndrome. In non-irradiated xerostomic populations, scintigraphy provides specific, albeit limited, diagnostic information. The procedure's ability to distinguish uptake failure from secretory failure may be a useful asset in guiding clinical management strategies and estimating outcomes.