Pure red cell aplasia associated with thymic lymphoid hyperplasia and secondary erythropoietin resistance.

Systemic disorders, often immune in nature, can sometimes be associated with the presence of thymic pathology. Thymic enlargement due to lymphoid hyperplasia or thymoma is a common occurrence in patients with myasthenia gravis. In patients with pure red cell aplasia, at least 10% to 15% of patients are found to have thymoma, usually of spindle cell or medullary type. Pure red cell aplasia with demonstrable thymic enlargement due to lymphoid follicular hyperplasia is distinctly unusual, and has not been previously reported. The authors report such a case developing in a patient with end-stage renal failure maintained on hemodialysis and erythropoietin therapy. Because the red cell aplasia resolved after thymectomy, the disease process was considered etiologically related to the reactive lymphoid hyperplasia.