What is the gold standard diagnostic test for Sjogren's syndrome?

• A. ANA
• B. Anti-Rho/Anti-La
• C. Biopsy
• D. Schirmer test

Answer: (C)

Labial minor salivary gland biopsy showing focal lymphocytic sialadenitis provides the most definitive confirmation of Sjogren's syndrome. The disease involves autoimmune attack on exocrine glands, so seeing organized clusters of lymphocytes infiltrating salivary tissue directly demonstrates the underlying process. A positive biopsy, typically with a focus score of at least 1 focus per 4 mm² of gland tissue, confirms the diagnosis.

Serologic tests like ANA or anti-Ro/La and functional tests such as the Schirmer test can support suspicion, but they are not definitive on their own because they are not specific to Sjogren’s. ANA can be seen in many conditions, and anti-Ro/La antibodies, while common, are not present in all patients. The Schirmer test assesses tear production and indicates sicca symptoms but does not prove the autoimmune cause. Thus, the biopsy provides the highest diagnostic certainty by showing the characteristic histopathology of Sjogren’s syndrome.