[Natural history of cardiac rhabdomyoma. Presentation of 2 cases with immunohistochemical study and review of the literature].

Two cases of cardiac rhabdomyoma have recently been observed in foetuses. The cardiac and muscular nature of the cells was confirmed by immunohistochemistry using monoclonal antibodies. A review of the literature shows that cardiac rhabdomyomas are usually considered to be hamartomas which are composed of primitive myocardial cells. Their spontaneous regression is often observed and apoptosis has been proposed as a possible mechanism of such a phenomenon. We propose that cardiac rhabdomyomas should be better considered as developmental vestiges rather than as true hamartomas. These vestigial structures would result either from a defect in differentiation, or from a defect in regression of primitive myocardial cells.