Plexiform Vasculopathy in Feline Cervical Lymph Nodes.

Plexiform vasculopathy refers to an endothelial proliferative disorder affecting cervical or inguinal lymph nodes of cats. The cause of this disorder and the origin of the proliferating endothelial cells are still unknown. In 4 cats with a history of a slowly growing, well-demarcated, nonpainful mass adjacent to the thyroid gland, an enlarged dark brown to red lymph node was removed. Histologically, the lymph nodes showed severe loss of lymphoid tissue with accumulations of erythrocytes. In addition, networks of capillary structures with well-differentiated endothelial cells on a collagen-rich stroma were observed, consistent with benign plexiform vasculopathy. Immunohistochemistry revealed the expression of the vascular endothelial markers CD31 and factor VIII-related antigen. In addition, immunolabeling with a Prox-1 antibody indicated a lymphendothelial origin. With respect to our findings, a lymphendothelial origin has to be considered in cases of intranodal vascular neoplasms.