Hi there. and welcome to HW. I think you'll find it a wonderful resource filled with caring people who have both personal and professional experience on these types of topics. I have RA, and recently have been dx with secondary sjogren's. My rheumatologist started me on plaquenil, but it did nothing at all for me. He added enbrel, and five months later, I started taking mtx with the enbrel. Right now, I'm taking all three drugs, but I've cut my plaquenil dose in half and will eventually phase it out altogether, as it is not necessary when you take enbrel and mtx. Interestingly, my eyes started bothering me in a major way right around the time I cut my plaquenil dose in half. Coincidence? Probably, but I'll keep an eye on it anyway (No pun intended).
In answer to your question, I don't believe that plaquenil has been associated with lymphoma, but having connective tissue disease in general, and sjogren's specifically, puts you at risk (although as you pointed out, it is rare). It is something that concerns me as well, and now I'm wondering if using a biologic (like enbrel) increases the lymphoma risk even more in someone with sjogren's? I believe there is someone else here that developed a low-grade lymphoma from taking enbrel, so perhaps they could offer more specific information.
Elcamino