Necrotizing vasculitis affecting medium-sized vessels (arterioles) located in the reticular dermis and hypodermis

Thrombus

Fibrinoid necrosis (pink material)

Inflammatory infiltrate rich in lymphocytes and polymorphonuclear leukocytes within the vascular wall, accompanied by leukocytoclasia, all contributing to destruction of the vessel wall

Erythrocyte extravasation

Fibrinoid necrosis (homogeneous pink material)

Intimal proliferation (inner layer of the vascular endothelium)

Arterioles are distinguished by the presence of a continuous elastic lamina, highlighted by Verhoeff–Van Gieson stain

Venules and veins exhibit a loose, compressed-appearing wall with variable and discontinuous elastic fibers