What methods determine salivary gland involvement in Sjogrens Syndrome?
Sialometry (sensitivity 56%, specificity 81%) can be used to quantitate saliva production. An unstimulated whole salivary flow rate of ≤0.1 mL/minute meets criterion for xerostomia. Scintigraphy (sensitivity 75%, specificity 78%) utilizes the uptake and secretion of Tc-99m pertechnetate following intravenous injection to quantitate salivary flow rates. Sialography is used to outline the salivary duct anatomy, but may predispose to pain, infection, or duct rupture. Both magnetic resonance imaging (MRI; sensitivity 81%, specificity 93%) and ultrasonography (sensitivity 69%, specificity 92%) can detect parenchymal heterogeneity.
Minor salivary gland (MSG) biopsy (sensitivity 80%, specificity 82%) is the gold standard for SS diagnosis. An incisional biopsy through the lower labial mucosa yielding 5 to 10 minor glands is adequate for assessment. An area of ≥50 lymphocytes is defined as a focus, with a focus score (FS) of ≥1 foci/4 mm 2 supporting a diagnosis of SS. The procedure may be complicated by persistent lip numbness in up to 6% patients. The findings in the MSG biopsy generally parallel involvement of major glands; therefore, biopsy of other salivary glands is generally not necessary.