A case of rheumatoid arthritis associated with Hashimoto's thyroiditis and thymoma

Dear Editor, Rheumatoid arthritis (RA) is an autoimmune disease, which is most common in adult females, and sometimes is associated with other connective tissue diseases, such as Sj€ ogren’s syndrome and systemic lupus erythematosus. However, the combination of RA, Hashimoto’s thyroiditis and thymoma is relatively less frequent. In this case report, we present a case of RA associated with Hashimoto’s thyroiditis and thymoma. A 38-year-old Chinese woman was admitted to our hospital because of an 11-year history of general arthralgia and persistent joint stiffness. The arthralgia affected mainly hand joints (especially the proximal interphalangeal joints) and wrists bilaterally. Morning stiffness was not evident and joint swelling improved after movement of the corresponding joints. Her finger swelling and arthralgia grew worse in 2009. The arthralgia began to affect the finger joints bilaterally, partially the distal interphalangeal joints, shoulders and knees. Duration of morning stiffness was 2–3 h and movement was obviously limited. She was taking non-steroid anti-inflammatory drugs (NSAIDs) for joint pain when necessary and there was no history of immunosuppressant therapy. The patient was admitted to our hospital because of exacerbated arthralgia and limited movement after a cold 1 month ago. Her thyroid was enlarged and she was diagnosed as having Hashimoto’s thyroiditis 8 years ago but without any treatment. On admission, physical examinations revealed mild swelling of the thyroid and stiffness of bilateral wrist joints. There was swan neck deformity in both hands. Tenderness was found in metacarpophalangeal joints and the proximal interphalangeal joints. Bilateral finger tip was deviated to the ulnaris side. Limited movement was also found in bilateral wrists, especially the left. Laboratory findings were as follows: anti-cyclic cirullinated peptide antibody, anti-keratin antibody and rheumatoid factor were positive; erythrocyte sedimentation rate was 106 mm/first h; anti-thyroglobulin antibody was over 2000 IU/mL; anti-thyroid peroxidase antibody was more than 1000 IU/mL; antinuclear antibody, anti-Sj€ ogren’s syndrome A antibody and C-reactive protein were positive. Liver function tests showed that the level of globulin was 39.1 g/L. Chest computed tomography (CT) scan disclosed a mass in the area of the thymus. Thymus nuclear magnetic resonance (NMR) detected that both thyroids were enlarged and there was a superior mediastinal mass on the left side. Thymoma was considered. The patient was then treated with meloxicam (7.5 mg twice daily), prednisone (30 mg once daily), amethopterin (10 mg weekly), sulfasalazine (0.75 g three times a day), hydroxychloroquine (0.2 g twice daily). In the meantime, some supporting therapies were taken, including administration of anti-osteoporotic and gastric mucosal protective drugs. Three months later, the symptoms ameliorated. As a result, meloxicam was discontinued and prednisone gradually was tapered to 10 mg daily. Swelling of joints almost disappeared, and in the meanwhile the thyroid apparently reduced. The patient has been self-reliant up to now. RA is a systemic autoimmune disease characterized by chronic destructive polyarthritis. Various kinds of autoantibodies can be examined in the sera of RA patients. The underlying mechanisms of RA include predisposing genes, infection factors, autoimmune response-induced immunolesions and repair. Hashimoto’s thyroiditis is an autoimmune disease and many kinds of thyroid antibodies, for example, anti-thyroid stimulating hormone receptor antibody, thyroglobulin antibody and antinuclear antibody, can be found in the sera of these patients. The mechanism of Hashimoto’s thyroiditis involves both humoral immunity and cellular immunity. This disease can coexist with other autoimmune diseases, such as RA, malignant anemia and rheumatic heart disease. Thymoma is the most common tumor of the anterior mediastinum, the mechanism of which is also related