Myopericytoma and arterial intimal thickening: the relationship between myopericytes and myointimal cells

Abstract

Myopericytomas with intravascular growth have been reported and have been occasionally documented as intraarterial. In a retrospective study, we assessed intraarterial growth in myopericytomas, co-existence with arterial intimal thickening (IT) and the relationship between the two. This retrospective study was undertaken using 11 myopericytomas evaluated in serial microscopical sections. The results in light microscopy, electron microscopy and immunohistochemistry [including α-smooth muscle actin (SMA), desmin and h-caldesmon] were evaluated. In four myopericytomas, we found intraarterial growth, with large areas of disrupted arterial wall and attachment of veins and venules, exhibiting angiogenic phenomena. Arterial IT was present and partially incorporated within the tumor (simulating medium-sized vessels). The neointimal (myointimal) cells shared morphological and immunohistochemical phenotype with the myopericytoma myoid cells, including α-SMA positivity and desmin negativity. Four of the remaining myopericytomas showed structures similar to arterial IT within the tumor. The findings shown here, including the association between myopericytomas and arterial IT, the incorporation of the latter into the tumor and the similar phenotype of their respective myoid and myointimal cells, support a close relationship between these processes. Histogenically, the pericytes of the penetrating neovasculature originating from the attached venules and veins may contribute to both lesions.