Case Number : Case 1068 - 28th July Posted By: Guest

Superficial thrombophlebitis vs. polyarteritis nodosa.

Cutaneous polyarteritis nodosa.

Polyarteritis nodosa.

Polyarteritis nodosa

Since the infiltrate is confined to the artery wall and to the subcutaneous fat immediately around it, I favor polyarteritis nodosa over nodular vasculitis.

Happy birthday, Romualdo!

PAN

The lumen of the vessel is obstructed by trombosis and the infiltrate is compromising only focally the vessel wall thickness, so I believe this is a case of Superficial thrombophlebitis. Special stain with Orcein or other elastic tissue stain is necessary to better differentiate artery and vein. Most cases of PAN has the lumen patent.

PAN

I called this PAN (polyarteritis nodosa). The differential diagnosis includes superficial thrombophlebitis and nodular vasculitis. The distinction between PAN and superficial thrombophlebitis can be very difficult. Elastin stains can be helpful as arteries have internal elastic lamina and veins do not. The assessment of smooth muscle bundle patterns can be very helpful; in veins the smooth muscle bundles are interrupted by collagen fibers, and in arteries the smooth muscle bundles are continuous, as they are in this case. I too favored nodular vasculitis less as the inflammation seems pretty confined to the vessels rather than showing significant involvement of the panniculus.