Lip biopsy increases the sensitivity of Sjögren’s syndrome diagnosis and is a key measure in the widely accepted diagnostic criteria, according to a multicenter Argentinian study.
Findings of the study were presented in a poster, “Diagnostic Performance of Labial Salivary Gland Biopsy, Serological and Clinical Data in Sjogren’s Syndrome. in Argentinian Multicenter,” at the recent American College of Rheumatology 2018 Annual Meeting in Chicago.
Lip biopsy (labial salivary gland biopsy, or LSGB) is an essential measure in both the AEGC 2002 and ACR 2012 criteria. However, there have been a limited number of studies that have evaluated its diagnostic value or assessed its relationship to antibody detection, which is also key in diagnosing Sjögren’s syndrome.
In this study, the researchers analyzed data collected between June 1996 and July 2017 from 1,101 patients with a mean age of 52 years.
Using the AEGC 2002 and ACR 2012 criteria, a total of 413 (37.5%) patients were diagnosed with Sjögren’s. Furthermore, 688 patients were diagnosed with nonspecific dryness syndrome unrelated to Sjögren’s inflammation (No-SS).
The Chisholm and Mason classification was used to score the lesions seen on lip biopsies. In this system, biopsies are classified from grade 1 to 4 based on the abundance of white blood cells seen in a small 4-mm2 area of the tissue.
Accumulation of white blood cells is an indicator of inflammation — the higher the number, the more severe the disease.
Researchers found that of the 413 Sjögren’s patients, 143 (34.6%) biopsies were considered grade 3, while 227 (55%) indicated a grade 4 classification. However, none of the biopsies from the No-SS group were classified as grade 3 or 4, confirming their diagnosis.
Anti-SS antibodies (anti-Ro and anti-La), antinuclear antibodies (ANA), and rheumatoid factors (RF) detected in blood samples are usually indicators of Sjögren’s syndrome. Although none of the No-SS biopsies were graded positive in their lip biopsies, some of those patients tested positive for anti-Ro (3.2%), anti-La (0.5%), ANA (13.5%), and RF (18.6%). These results show that it was the biopsy data that helped correctly diagnose them.
The association between anti-Ro, anti-La, ANA, and RF and the lip biopsy was calculated using a statistical measure called the odds ratio. It estimated the chances of a positive antibody test when an LSGB scored positive.
A significant link between LSGB and anti-Ro, ANA, and RF was reported. The researchers found that for a positive biopsy, the chances of a positive anti-Ro, ANA, and RF blood test were 6.33, 3.26 and 3.05 times higher, respectively.
Results indicated a strong association between the antibodies and a positive biopsy test. The antibodies are very specific; however, their sensitivity to screen for Sjögren’s is low. Therefore, according to the researchers, “LSGB has a great value in seronegative patients.”
Also, with this correlation, LSGB can differentiate well between true positive Sjögren’s syndrome and false positives.
“LSGB is a simple, safe, and useful tool for the diagnosis of Sjögren’s syndrome. It exhibits an adequate balance between sensitivity, specificity, positive and negative predictive value,” the study concluded.