Invasive thymoma: unique presentation as an anterior chest wall mass

A 57-year-old white woman presented with pericardial effusion and an anterior superior mediastinal mass protruding through the sternum. The diagnosis of thymoma was established by the light and electron microscopic features of a biopsy specimen and a pericardial aspirate. The tumour was a thymic carcinoma, a recently described variant characterized by cellular atypia, enhanced invasiveness, and a higher incidence of metastases. Presentation as an anterior chest wall mass has not been described. Response to radiotherapy was slow and incomplete, and tumour progression occurred during treatment with cisplatin. The chemotherapy of thymoma is reviewed: some apparent responses to agents that are primarily lympholytic may represent the elimination of non-neoplastic lymphocytes from the tumour mass, with spurious radiological improvement and theoretically a risk of tumour enhancement.