Characterization and outcomes of 414 patients with primary SS who developed hematological malignancies

Objective: To characterize 414 patients with primary SS who developed hematological malignancies and to analyze how the main SS- and lymphoma-related features can modify the presentation patterns and outcomes. Methods: By January 2021, the Big Data Sjögren Project Consortium database included 11 966 patients fulfilling the 2002/2016 classification criteria. Hematological malignancies diagnosed according to the World Health Organization (WHO) classification were retrospectively identified. Results: There were 414 patients (355 women, mean age 57 years) with hematological malignancies (in 43, malignancy preceded at least one year the SS diagnosis). 376 (91%) patients had mature B cell malignancy, nearly half MALT lymphoma (n = 197), followed by DLBCL (n = 67), nodal MZL lymphoma (n = 29), CLL/SLL (n = 19) and follicular lymphoma (n = 17). Rates of complete response, relapses and death were 80%, 34% and 13%, respectively, with a 5-year survival rate of 86.5% after a mean follow-up of 8 years. There were significant differences in age at diagnosis (younger in MALT, older in CLL/SLL), predominant clinical presentation (glandular enlargement in MALT lymphoma, peripheral lymphadenopathy in nodal MZL and FL, constitutional symptoms in DLBCL, incidental diagnosis in CLL/SLL), therapeutic response (higher in MALT lymphoma, lower in DLBCL) and survival (better in MALT, nodal MZL and FL, worse in DLBCL). Conclusion: In the largest reported study of hematological malignancies complicating primary SS, we confirm the overwhelming predominance of B cell lymphomas, especially MALT, with the salivary glands being the primary site of involvement. This highly-specific histopathological scenario is linked with the overall good prognosis with a 5-year survival rate of nearly 90%.