because malignant hemangiopericytomas disclose smooth muscle differentiation by ultrastructure , but do not express alpha-smooth muscle actin , as normal pericytes and glomus cells , it is suggested that these neoplasms represent highly vascularized smooth muscle neoplasms , ie , poorly differentiated leiomyosarcomas derived from vascular smooth muscle cells or their equivalent , the pericytes , which have lost alpha-smooth muscle actin as a differentiation marker that is similar to many conventional poorly differentiated leiomyosarcomas .
C0007634
cells
C0007589
differentiation