SIALOLITHIASIS - DIFFERENTIAL DIAGNOSTIC PROBLEMS IN FINE-NEEDLE ASPIRATION CYTOLOGY

Sialolithiasis with obstruction of major salivary gland ducts can lead to clinical tumefaction related to cystic dilatation. In addition to mucus accumulation, these pseudoneoplasms feature hyperplasia and squa mous metaplasia of the ductal lining epithelium, with varying degrees of inflammation. The authors report five examples of this lesion aspir ated from two males and three females ranging in age from 45 to 80 yea rs (median 65 years). Three were in the submaxillary gland, and two we re in the parotid. In three cases, stone fragments were identified, an d diagnoses of sialolithiasis were rendered; two of these patients und erwent surgical excision. The remaining two cases showed prominent foa m cells and metaplastic squamous cells in a mucoid background that mim icked low grade mucoepidermoid carcinoma. Stone fragments were not ide ntified and a differential diagnoses of sialolithiasis versus low grad e mucoepidermoid carcinoma were suggested. Surgical excision revealed sialolithiasis in both instances. When stone fragments are identified in aspirated material, these cases pose little diagnostic difficulty. However, when this material is not present, epithelial changes and muc us accumulation may be difficult to distinguish from low grade mucoepi dermoid carcinoma. Cautious interpretation is suggested in this settin g.