Plexogenic angiopathy in pulmonary intralobar sequestrations: pathogenetic mechanisms.

Vascular remodeling to form plexiform (glomoid) lesions is a little-known manifestation of intralobar pulmonary sequestration. We describe histologic and immunohistochemical features of these lesions in resected specimens from three subjects aged 3, 19, and 28 years. The vascular changes, which included medial and intimal thickening, angioblastic proliferation, plexiform lesions, and dilation lesions, occurred in a setting of hypoxia, chronic inflammation, and high pressure and flow via a systemic arterial supply. We demonstrated strong immunoreactivity of the angioblastic tissue and the plexiform lesions with antibodies to muscle actin, alpha-smooth muscle actin, and vimentin, and weak to absent reactivity with antibody to desmin. We suggest that in these sequestrations plexiform lesions develop via angioblastic proliferation at arterial branch points and that dilation lesions develop from subsequent expansion of distal anastomoses.