Case Number : Case 1094 - 2nd September Posted By: Guest

Nodular vasculitis.

Agree. Nodular vasculitis / erythema induratum.

Nodular vasculitis.

The inflammation appears to be centered on a medium sized vessel on low power (not sure if artery or vein).
The fat lobules away from this vessel are not affected. ?Superficial thrombophlebitis ?PAN

The inflammation is limited to the vicinity of the vessel, no extension to the whole fat lobules, no extensive fat necrosis. I think this speaks against nodular vasculitis. I agree with Arti that this could be superficial thrombophlebitis or PAN. Favour superficial thrombophlebitis based on clinical history.

I also do not see extensive lobular necrosis, a find so common in Nodular vasculitis. I don´t like to decide between PAN and superficial trombophlebitis without an elastic stain, but since there´s no big destruction of the vessel wall and the lumen is obstructed I think this case is probably superficial trombophlebitis.

This is quite a difficult case; thank you for all of your comments. I agree that the elastin stain is the best way to distinguish between superficial thrombophlebitis and PAN; however, in inflammatory situations the elastin can be destroyed (see recent paper by Hall LD, Elston DM, et al.). A relatively reliable H+E method is to look for intervening collagen fibers in the vessel wall. Veins have these; arteries do not. The paper by Hall et al has some nice visuals of these two settings (PAN and ST) comparing the smooth muscle patterns. I called this superficial thrombophlebitis based on the clinical setting and the smooth muscle patterns of the vessels. Nodular vasculitis is also an excellent thought, and a differential diagnostic consideration. I favored this less as the infiltrate seems relatively localized (although there is some spillover into the lobules) and not as diffuse as cases of NV that I have previously encountered.

Agree this vessel is a vein but I was favouring nodular vasculitis too. Uma - what in the clinical setting was more typical of thrombophlebitis?

Richard, the lesions were smaller than those typically found in panniculitides, had a linear, rope like pattern in the overlying skin, and 'came and went', according to the patient. Based on the clinical appearance, the clinicians favored superficial migratory thrombophlebitis.