Myofibroblastoma: a tumour of myofibroblasts

A myofibroblastoma occurring in the abdominal cavity of a 15 year old boy is described. This tumour was diagnosed as a low grade sarcoma by light microscopy but electron microscopy showed that the tumour was composed almost entirely of myofibroblasts and a few macrophages. Intermediate forms between myofibroblasts and macrophages were not seen nor were any fibroblasts seen in the main tumour mass. Total excision was impossible because the tumour had trapped loops of bowel and was adherent to the abdominal organs. The patient died of cachexia and haemorrhage but there were no distant metastases nor was there any marked infiltration of the abdominal organs. This case and a review of the literature shows that myofibroblastomas are locally aggressive tumours which do not metastasize and that if total excision is possible an uneventful recovery can be expected.