Taste disorder in a patient with invasive thymoma without myasthenia gravis: a rare case report

Taste disorder has been reported as a non-motor symptom caused by myasthenia gravis (MG)-related autoimmune mechanism. Taste disorder in some cases recovered along with MG treatment, such as thymothymectomy or immunosuppressive treatment. However, symptom of taste disorder in thymoma patients without MG is very rare. Here, we reported a case of invasive thymoma without MG which had concurrent taste disorder. The taste disorder was successfully treated with cyclosporine. A female in her seventies had an anterior mediastinal tumor of 78-mm in diameter and pleural dissemination. She also had taste disorder, limited to sweet taste, and pure red cell aplasia (PRCA). Symptoms and physical findings showed no feature of MG. Pre-operative blood examination revealed no elevation of anti-acetylcholine receptor antibody . Extended total thymothymectomy and resection of all detectable pleural disseminations was performed. Pathological examination showed type B3 thymoma. Clinical stage was Masaoka stage IVa. After operation, there was no improvement in taste disorder and PRCA. Six months after operation, cyclosporine was administered for PRCA. In parallel with gradual improvement of anemia, taste disorder also gradually improved. Three months after the first administration of cyclosporine, taste disorder had completely recovered. This is the first case of taste disorder without any myasthenic status, which recovered with immunosuppressive drug. Our case suggested the potency of immunosuppressive treatment for taste disorder associate with thymoma without MG.