LYMPHOMA RISK: Lymphoma is a very severe complication of primary Sjögren's 
syndrome: 5 to 10% of patients followed for more than 10 years will develop a 
lymphoma. Predictive factors include serum monoclonal immunoglobulins or 
cryoglobulins and a B clone population in accessory salivary glands. TYPICAL 
CLINICAL AND HISTOLOGICAL PRESENTATION: Mucosal involvement (parotid as well as 
gastric or pulmonary localizations) is frequent. According to the recent 
classification of lymphomas, most lymphomas developing in patients with 
Sjögren's syndrome are B lymphomas of the marginal zone: MALT lymphomas or 
low-grade nodal monocytoid lymphomas which are sometimes not identified until 
transformation to the giant cell stage. SIMILARITIES WITH HEPATITIS C LYMPHOMAS: 
The pathophysiology of lymphoma in Sjögrën's syndrome remains unknown. To date, 
there is no argument favoring a viral infection or a deregulation of a unique 
oncogene or anti-oncogene. Certain similarities between lymphomas in Sjögren's 
syndrome and lymphomas associated with hepatitic C virus would suggest a common 
pathogenisis: possibly a permanent stimulation of auto-reactive B cells carrying 
a surface immunoglobulin with rheumatoid factor activity in the target organs of 
the autoimmune disease. These B lymphocytes would then proliferate secondarily.