A composite malignant tumour of the elderly female breast.

A composite malignant tumour arising in the breast of an elderly woman is described. The cystic tumour containing areas of squamous metaplasia, bone formation, adenocarcinoma, and osteosarcoma was surrounded by the typical changes of mammary dysplasia (fibroadenosis). The classification and acceptance of such tumours is highly debatable. There is no one acceptable classification of breast sarcomas and hence the prognosis of such neoplasms, particularly those containing heterologous tissues, is poorly defined. Evidence is presented in support of such composite tumours as being definite entities which arise from the closely associated epithelial and mesenchymal components of the breast simultaneously.