LEIOMYOMATA. 



305 



such tumors have occurred congenitally in the heart and caused 

 death. Such tumors have also been found in the kidney, 

 mixed with sarcomatous tissue and malignant in proportion to 

 the amount of the latter (Fig. 134). 



Leiomyomata are of much more common occurrence the 

 most frequent seat being the uterus, though they may occur 

 wherever unstriped muscle-tissue is normally found. They are 

 formed of bundles of muscle-cells, closely packed and inter - 



FIG. 134. 



Rhabdomyosarcoma of the kidney, a, a, a, imperfectly developed striated muscle- 

 fibres ; b, tissue composed of small round and spindle-shaped cells, separated by 

 considerable delicate fibrous intercellular substance. In other parts of the growth, 

 which was the size of the fist, this tissue was more distinctly sarcomatous and 

 the amount of muscular tissue smaller. The child from which this tumor 

 was removed was about two years old. 



lacing in every direction. When there is a large amount of 

 connective tissue between the bundles they are termed fibro- 

 myomata. On account of the wavy course of the muscle- 

 cells, in microscopical section they seldom are seen in their 

 entire length, though they may be isolated by teasing out a 

 portion of the tumor. The characteristic feature is the 

 presence of the long rod-shaped nuclei circular, however, 

 if cut transversely (Fig. 135). Their appearance suggests 

 spindle-celled sarcoma, but in the latter the cells are not 



20 Hist. 



