Thymic carcinoma: a clinicopathological and immunohistological study of 19 cases.

Aims: To study 19 cases of primary thymic carcinoma in order to define the clinicopathological features and the precise histochemical profile of this rare and heterogeneous group of tumours of the anterior mediastinum.

Methods And Results: The study group consisted of 13 males and six females, with a mean age of 58.5 years (range 29-75 years). Superior vena cava syndrome and chest pain were the main presenting symptoms. Three patients were asymptomatic. No patient had myasthenia gravis. Six different histological types were identified: neuroendocrine tumours (six patients), epidermoid carcinoma (five patients), sarcomatoid carcinoma (three patients), lymphoepithelioma-like carcinoma (two patients), mucoepidermoid carcinoma, clear cell carcinoma, and undifferentiated carcinoma (one patient each). The clear cell carcinoma was associated with a thymic cyst. No association with thymoma was observed. Surgical resection, performed in 10 cases, was complete in two. Sixteen patients received thoracic radiation, and 11 received systemic chemotherapy. Follow-up information was available in 16 cases; 12 patients presented with local or metastatic relapse, and 10 patients died of their tumour. The overall 5-year survival was 14.5%.

Conclusion: Primary thymic carcinoma is a very heterogeneous group of tumours of the anterior mediastinum with an aggressive clinical behaviour, and a poor overall prognosis.