Subacute necrotizing sialadenitis: report of 7 cases and a review of the literature.

Subacute necrotizing sialadenitis (SANS) is a nonspecific inflammatory condition of unknown etiology affecting oral minor salivary glands. The lesion is most often characterized by a localized palatal swelling, accompanied by an abrupt onset of pain. In this report, we describe the clinical, microscopic, and ultrastructural features of 7 new cases of SANS and combine them with those of 15 cases previously published in the English language medical literature. Patient ages ranged from 15 to 45 years, with a mean age of 21.9 years. A male to female ratio of 3.4 to 1 was observed, but probably reflects a male sampling bias because 14 of the 22 cases occurred in a military population. Seventeen cases occurred on the hard palate, 4 on the soft palate, and 1 on the tonsillar pillar. The lesions were nonulcerated swellings ranging in size from 0.3 to 2.5 cm in diameter. All lesions except one were painful, and most had been present for a week or less at the time of diagnosis. Histopathologic features included diffuse involvement of minor salivary glands by lymphocytes, histiocytes, neutrophils, and variably by eosinophils. Loss of acinar cells, early acinar cell necrosis, and atrophy of ductal cells were also observed. Although possible viral particles have been reported ultrastructurally in some cases of SANS, none were observed in our study. SANS appears to be a self-limiting process with most cases resolving 2 to 3 weeks after biopsy. SANS has been questioned as an entity by some investigators who prefer to include it within the spectrum of necrotizing sialometaplasia. However, we believe there is justification for the separation of these 2 entities based on clinical and histopathologic parameters. Although the specific etiology of SANS remains unknown, it most likely represents an infectious process or perhaps an immune response to an unknown allergen.