Abstract: Specimens of 22 cases of arteriovenous malformations (AVMs) and 22 cases of cavernous malformations (CMs) were paraffin processed with immunohistochemical staining. Four types of matrix and structural proteins (LM, FN, Ⅳc, αSMA) were examined. The results were analyzed by two observes blinded to the antibody and lesion type, and were evaluated in three classes. The AVMs exhibited positive for LM in 9/22, while none of the CMs demonstrated LM expression (P<0.01). By contrast, FN expression was more prominent in CMs than that in AVMs (P<0.01). There was intense and diffuse FN staining in all of the CMs. The expression of Ⅳc and αSMA was noted to be intense throughout the 44 vascular malformations studied. The study demonstrated a clear difference in the expression of FN and LM among the different types of vascular malformations. CMs appeared to exhibit immature vessels devoid of LM, consistent with ongoing dysangiogenesis within a FN rich matrix. In contrast, AVMs represented more mature vessels which expressed LM, consistent with dysvasculogenesis .

Key words: matrix proteins, arteriovenous malformations, cavernous malformations