Myofibroblastoma of the breast: genetic link with spindle cell lipoma

Mammary myofibroblastoma is a rare tumour, mainly occurring in male patient s. This paper describes two cases of mammary myofibroblastoma, with typical histological features, including the presence of fat cells and mast cells, Immunohistochemically, the spindle cells stained positively for desmin and CD34. Cytogenetically, both tumours showed partial monosomy 13q and in cas e 1, there was, in addition, partial monosomy 16y, Rearrangements affecting 13q and 16q occur typically in spindle cell lipomas, In addition to histol ogical similarities, the hitherto unreported chromosomal changes in mammary myofibroblastoma, which are similar to the chromosomal aberrations in spin dle cell lipoma, strongly suggest a link between these two tumours and are not in favour of myofibroblastoma being a primary solitary fibrous tumour o f the breast. Copyright (C) 2000 John Wiley & Sons.