Malignant mesenchymoma as a primary urinary bladder tumour.

A rare case of primary malignant mesenchymoma of the urinary bladder is reported in a 72 year old man. The tumour showed predominantly a leiomyosarcomatous component with foci of malignant bone, cartilage and myxomatous areas. The importance of studying multiple sections from the tumour is stressed to arrive at the proper diagnosis.