Thymoma--a study of 60 cases in Singapore.

Of 60 cases of thymomas studied in Singapore between 1988 and 1992, the histogenetic classification proposed by Müller-Hermelink was successfully applied to subtype 58 cases. There were 20 (33%) cortical, six (10%) predominantly cortical, three (5%) medullary and 12 (20%) mixed thymomas. Twelve (20%) cases were well differentiated thymic carcinomas and five (8%) were classified as other thymic carcinomas. The pathological and clinical features are presented in detail. These subtypes showed significant correlation with invasive behaviour (stage) and myasthenia gravis. We conclude that the Müller-Hermelink classification has predictive utility and represents a major step towards the understanding of the biology of thymic epithelial tumours.