Subclinical lead exposure: a possible cause of gout.

The relation between myasthenia gravis and thymoma or microscopic hyperplasia of the thymus is well known.' The syndrome of PRCA and thymoma is also well established. Roland2 reviewed 43 cases of the latter and reported the incidence of thymoma in PRCA in adults as 57°h. Six ofthese patients had associated myasthenia gravis and about one-third also had depression of the myeloid or megakaryocyte series, or both. In three patients the thymomas were too small to be shown by radiography and were unsuspected findings at necropsy. Thirty-two of the 43 patients received specific therapy, including thymectomy, thymic irradiation, corticosteroids, androgens, and splenectomy in various combinations: but only one patient had a remission on corticosteroid treatment alone. There is now much evidence pointing to an autoimmune basis to PRCA,3 and immunosuppressive drugs may be used in treatment, often with satisfactory results. A humoral inhibitor may be secreted by a thymoma, but a disruption of immunological homeostasis, possibly mediated by a loss of controlling function of T lymphocytes, seems more likely.4 IgG serum inhibitors have been demonstrated against erythroid marrow and also against circulating erythropoietin.5 These inhibitors have always disappeared with remission after thymectomy or immunosuppressive treatiment. Our patient was unusual in that his peripheral red cells were coated with IgG. But the most remarkable feature of the case was the prompt and gratifying response to corticosteroids alone. This is rare among a series of reports of patients requiring multiple transfusions, major surgery, and immunosuppressive drugs to try to achieve remission.