MYOFIBROBLASTOMA OF THE BREAST - A STUDY OF 8 CASES

Eight cases of breast myofibroblastomas are reported: two in men and s ix in post-menopausal women. This study and a review of the 19 publish ed cases permit to define more precisely the particular features of th is rare and benign mesenchymal tumour. Good demarcation, lack of necro sis and nuclear atypia argue for the benign nature of the lesion. It i s made up of spindle cells (mainles myofibroblasts) which are positive for vimentin and not for S 100 protein or epithelial markers. Alpha-s mooth muscle cell actin and desmin labelling are heterogeneous. This i mmunohistochemical study underlines the variable results of myofibrobl asts for smooth muscle markers reflecting different degrees in their d ifferentiation, without resolving the question of their origin. A simp le surgical excision is required for this benign lesion. No recurrence has never been observed.