To evaluate the diagnostic accuracy of ultrasonography (US) of the salivary glands versus histologic examination in detection of salivary gland involvement in primary Sjögren's syndrome (SS).
Thirty female patients with primary SS diagnosed according to the European criteria and 30 female subjects of similar age with dry mouth (symptomatic controls) due to other selected disorders were studied. Evaluation of salivary involvement was by 2 independent observers for both the parotid and submandibular glands using US score (range 0 to 4) that assigns points to the different degree of glandular inhomogeneity. Lip salivary gland (LSG) biopsies were graded according to the Chisholm and Mason classification system and by morphometric analysis. The area under receiver operating characteristic (ROC) curve was employed to evaluate the screening method's performance.
Through ROC curves salivary gland US arose as the best performer, followed by the volume percentage of inflammatory cells and by the semiquantitative focus score. The difference between area under ROC curve of salivary gland US and lymphocytic focus score was significant (p = 0.044), reflecting the accuracy of the imaging diagnostic assessment. No differences arise between areas under the ROC curve of salivary gland US and volume percentage of inflammatory cells (p = 0.610) and between volume percentage of inflammatory cells and semiquantitative focus score (p = 0.081). Attempts to assess the independent contribution of the fractional composition of the LSG biopsy as the predictor of US score showed a significant contribution of both the fractional composition of inflammatory infiltrate (p = 0.01) and intralobular ducts (p = 0.02). These findings indirectly suggest that the US abnormalities we found were strongly related to SS.
These results conclusively indicate that quantitative assessment of salivary gland ultrasonography is a very useful method fdr evaluating salivary gland involvement in SS and can replace other diagnostic techniques, such as sialography or salivary scintigraphy.