Proliferative Vasculopathy and Cutaneous Hemorrhages in Porcine Neonates Infected with the Porcine Reproductive and Respiratory Syndrome Virus

Severe cutaneous hemorrhages with dermal and subcutaneous capillary angioplasia were seen in aborted and stillborn piglets, concurrently with an acute outbreak of porcine reproductive and respiratory syn- drome virus (PRRSV) abortions. Histologically, the lesions consisted of angioblastic endothelial cells and im- mature capillary vascular structures coursing through the edematous myxomatous dermis and subcutis. Prolif- erating capillaries often were surrounded by large and foamy macrophages that stained positively for PRRSV by immunohistochemistry. The sudden appearance of these vascular lesions during the PRRSV outbreak and their abrupt disappearance after the abortion storm, along with the immunohistochemical localization of PRRSV- positive macrophages adjacent to the proliferating capillaries, suggest that PRRSV likely played a role in the development of these unusual lesions.