Dear triumphe64,
In doing my research, I did indeed find thymomas implicated in PRCA (why do I always think Pro Rodeo Cowboys when I see that acronym?)
They are also implicated in a variety of other autoimmune diseases including myasthenia gravis, systemic lupus erythematosus, and pernicious anemia. Reading about the relationship between thymomas and autoimmune diseases is what got me wondering, "Aplastic anemia is thought to be an autoimmune disease. Could there be a link with thymoma?" Sure enough, I found a few journal articles proposing a link between the two diseases.
Since thymomas are often discovered when the patient has a CT scan for something else, I have to wonder if I'd had a CT scan when first diagnosed with AA could I have avoided a relapse? Guess there is no way to know for sure, but I'd be curious to know how many AA patients have a CT scan as part of their diagnostic workup, especially those who are treated with ATG rather than going to transplant. I was told my clinic does not do them routinely for AA patients unless a patient will have a transplant and then it's done mostly to check the lungs for potential fungal infections.