TUMOURS OF THE THYMUS
Thymomas are rare Tumours of the thymic epithelium that usually occur in adults (average age at onset of 48 years) and are usually sporadic. About 65% are benign, but when they occur in children, they are more likely to be malignant. Familial occurrence is rare, but a sibship has been described in which two of three siblings died of thymoma (Matani and Dristsas 1973). Malignant epithelial Tumours of the thymus (thymic carcinoma and thymoma) have also been described in two members of a sibship (Wick et al. 1982).
Nicodème et al. (2005) described a family harboring a constitutional translocation t(14;20)(q24;p12) in which 3 of 11 translocation carriers developed a thymoma (RAD51L and BMP2 were suggested as candidate genes).
Other Tumours that may involve the thymus are carcinoids, germ cell Tumours, neurogenic Tumours, thymolipomas, and Hodgkin disease. About one- third of thymic carcinoids are associated with multiple endocrine neoplasia type 1 (MEN 1). A possible genotype–phenotype association between thymic carcinoids and truncating MEN1 mutations has been reported (Lim et al. 2006).