The importance of minor salivary gland biopsy in prediction of lymphoma in Sjögren's syndrome: should we be obtaining more information about prognosis from minor salivary gland samples?

Theander, 1 in this issue, provides an important contribution with the article 'Lymphoid organization in labial sali-vary gland biopsies is a possible predictor for the development of malignant lym-phoma in primary Sjögren's syndrome'. It has been known for many years that ectopic germinal centres are present in minor salivary gland biopsies of a sub-population of patients with Sjögren's syndrome (SS). The frequency of SS patients with an ectopic germinal centre in the minor salivary gland biopsy has ranged from 10% to 25%. 2 – 4 Previous studies by Jonsson and his research group have described the clinical and laboratory characteristics of SS patients with ectopic germinal centres in their minor salivery gland biopsies. 5 – 9 Other groups have also used histology, immunohistol-ogy and gene profi ling to characterise the ectopic germinal centre in SS. 10 – 14 In the current paper, the frequency of ectopic germinal centres was somewhat lower than in previous publications. The goal has been to determine the risk of B cells undergoing transition from benign lym-phoproliferation to overt malignancy. 15 The current study 1 extends those studies by emphasising the increased risk of lymphoma in SS patients whose minor salivary gland biopsy contains an ecto-pic germinal centre. This is not a new concept, because an association between ectopic germinal centre formation and lymphoma development in primary SS was initially proposed in 1999. 16 Despite the important prognostic information to be gained from a more detailed analysis of the minor salivary gland biopsy, most rheumatologists in the USA do not obtain biopsies, and oral pathologists do not routinely examine them critically for the presence of ectopic germinal centres. At present, the minor salivary gland biopsy is used in the USA predominantly either in the research setting or as an 'obliga-tion' to fulfi l SS criteria in the patient lacking antibody to SS-A or SS-B. The current article emphasises the need for rheumatologists to obtain minor salivary gland biopsies as a method to predict the risk of lymphoma and for the pathologist to read the biopsy with attention to ectopic germinal centres as well as focus score. In addition to routine histology, the detection of ectopic germinal centres may be improved by the use immunohis-tology to detect both particular subsets of B cells and dendritic cells. Monoclonal antibodies have also been used to evaluate the types of cells in the lip biopsy, although generally on a research …