TU.MDI^S. 



297 



Leiomyomata are fuund most frequently in those locations in 

 which involuntary muscle tissue normally exists, as the uterus, 

 bladder, intestine, etc. The}' are nodular or diffuse, dense, pale 

 pink masses appearing ver)- similar to fibromata. Microscopic- 

 ally they are composed of miscellaneously arranged involuntary 

 muscle cells. They differ from fibromata in that the muscle cells 

 are thicker and usually not as long as the fibres of fibromata. 

 Frecjuentlv thev are combined with fibromata forming a leiomyo- 

 fibroma, making the diagnosis more difficult. Leiomyoma cells 

 may be very similar to the cells of a spindle-celled sarcoma, but 



Fig. 15-. — Leiomj-oma, small intLStine. mule. 



the nuclei of the former are long and rod-shaped while those 

 of the latter are oval in shape, a characteristic usually sufficient 

 for diagnosis. The cytoplasm of -the leiomyoma cells stains 

 densely with acid stains. 



Rhabodomyomata have been found in the kidney, ovary and 

 testicle. They are probably the result of the development of 

 misplaced embryonic myoblasts. These tumors are usually pale 

 in color. In microscopic section the cells are irregularly striated, 



