||The plaques and nodules contain both a vascular and a cellular component. The vascular component consists of a proliferation of benign, irregularly shaped capillaries, with swollen pleomorphic endothelial cells. The proliferation of endothelial cells in angiolymphoid hyperplasia points to an inflammatory reactive etiology.
The cellular component consists of a dense cellular infiltrate of numerous eosinophils, lymphocytes, histiocytes, and mast cells. Eosinophilia in the peripheral blood may occasionally be present.
With lesions which have been present over one year in duration, the lymphoreticular hyperplasia produces lymphoid follicles which contain germinal centers.