Prevalence and clinical presentation of lymphoproliferative disorder in patients with primary Sjögren's syndrome.

Lymphomas are one of the serious complications of the primary Sjörgen's Syndrome (pSS). The aim of the study was to evaluate the frequency of lymphoma in pSS. The singe-center retrospective study included 198 Caucasian patients, who met diagnostic criteria for pSS. The type of lymphoproliferative disorder was classified according to the WHO 2016 classification. The mean time of observation, after pSS diagnosis, was 48 weeks. Focus score (FS) ≥ 1 was present in 85% of the patients, and anti-SSA antibodies were detected in 84%. Rheumatoid factor was detected in 130 (65%) patients. Mean disease activity index, according to EULAR Sjörgen's Syndrome disease activity index (ESSDAI), was 8.3 points at the moment of pSS diagnosis. Complement C3 was decreased in 14% of the patients, while 10% showed reduced complement C4. Four patients (2%) were diagnosed with a lymphoma. Most of the patients were diagnosed with mucosa-associated lymphoid tissue lymphoma (MALT), in whom the tumour was located in the parotid gland, and in one patient the stomach was involved. Finally, one patient was diagnosed with a rare B-cell small lymphocytic lymphoma located in the lungs. In this article, we present detailed characteristics of each case. In analysed population the frequency of lymphoma in the course of pSS in patients with pSS is 2%. The variety of lymphoma types in pSS patients imposes individual monitoring in each patient at every check-up visit for disease activity.