Thymoma: a clinico pathological study of 21 cases and assessment of prognostic features.

This is a retrospective and comprehensive study of 21 cases of thymoma treated during a period of 30 years (1954-1984). The tumors were staged into 3 categories: stage 1 for encapsulated completely resectable tumor, stage 2 for nonresectable intrathoracic tumor and stage 3 for tumor with extrathoracic spread. According to their lymphocytic content tumors were separated into 3 groups: 1) predominantly epithelioid (PE); 2) mixed cellular (MC) and predominantly lymphocytic (PL). Incidence of recurrence and survival were correlated with various treatment modalities. The tumor occurred in all age groups with highest incidence in the fourth decade. Six cases were asymptomatic. Myasthenia gravis was present only in one case. The most important prognostic factor was the stage of the tumor. Five-year survival was 69% for stage 2 and 0% for stage 3. All 12 patients who died with evidence of residual disease had PE tumors. Lymphocytic participation might be indicative of a residual functional competence and appears to confer a more favourable prognosis. This is a tumor of uncertain malignant potential which should be excised or debulked, and staged. Post-operative radiotherapy appears to prevent recurrence and improve the prognosis in stage 2. No therapeutic benefits were seen in the stage 3 cases. The value of chemotherapy is uncertain.