Thymic carcinoma originating from the mid-posterior mediastinum

An unusual thymic carcinoma in a 74-year-old woman is described. Initial chest CT revealed a mass at the mid-posterior mediastinum. Transbronchial fine needle biopsy of the mass failed to provide a definite diagnosis. The mass was treated as a malignant mediastinal tumour, and chemoradiotherapy was performed as initial treatment. The patient died 5 years after receiving primary treatment. The results of postmortem microscopic examination, including immunohistochemical study with CD5 antibody, were consistent with thymic carcinoma. This case is interesting in that the mid-posterior mediastinum is the site where thymic carcinoma is least likely to originate.