26th January 2024

Diagnosis

The diagnosis of primary SS can be made in patients with objective findings of ocular and/or oral dryness and evidence of autoimmune exocrine glandular dysfunction. These clinical features, in combination with serological and in some cases, histopathological or radiological findings, assist in making a diagnosis of SS. 

• Ophthalmological tests used to investigate for dry eyes include the Schirmer test, tear break-up time and ocular surface staining. 
• Evaluation of salivary hypofunction: On physical examination, lack of salivary pooling under the tongue may be found, and testing such as whole sialometry (also called Saxon test) may be done. Imaging such as US may show characteristic salivary gland parenchymal changes, including a hypoechoic linear band, cysts and calcifications. MRI may show a nodular pattern of parenchymal changes such as fatty infiltration, fibrosis, and ductal dilatation. 
• Serological testing: Positive testing for Anti-Ro/SSA antibodies with or without Anti/La/SSB antibodies. Positive ANA and Rheumatoid factor, in combination with other clinical features, may also support a diagnosis of SS. 
• Salivary gland biopsy: A labial salivary gland biopsy is taken from the lower lip, and the key histological feature is focal collections of tightly aggregated lymphocytes (lymphocytic foci). 

Diagnostic criteria

The 2016 ACR/EULAR classification criteria for diagnosis of primary SS are based on a weighted scoring system. They can only be applied to an individual with at least one symptom of ocular or oral dryness or suspicion of SS based on glandular enlargement or the presence of characteristic extra-glandular involvement. An individual can be classified as having primary SS if the total score is four or more. The domains include labial salivary gland with focal lymphocytic sialadenitis, Anti-SSA/Ro positivity (each one 3 points), ocular staining score >5 in at least one eye, Schirmer’s test <5mm/5minutes in at least one eye and an unstimulated whole saliva flow rate <0.1ml/minute (each one is 1 point).