[A case of thymoma and hypogammaglobulinemia (Good's syndrome) with lichen planus].

A 72-year-old patient was admitted to our hospital because of painful tongue and loss of taste. A mediastinal mass on X-ray of the chest had been seen for 30 years, however no symptom was developed. Lichen planus was seen in his oral cavity. Hematological test showed decrease of all classes of immunoglobulin. CT and MRI of the chest showed a huge mediastinal mass. Needle biopsy was performed, giving rise to the diagnosis of thymoma with hypogammaglobulinemia (Good's syndrome). Intravenous immunoglobulin infusion, which is known to be effective to chronic diarrhea of this syndrome, improved his diarrhea. Lichen planus may be caused by T cell abnormality as suggested previously. Resection of the thymoma was not performed, since it does not improve hypogammaglobulinemia. This is a rare case of Good's syndrome with lichen planus.