Cutaneous arteriolitis: A novel cutaneous small vessel vasculitis disorder clinicopathologically different from cutaneous polyarteritis nodosa and cutaneous venulitis.

Cutaneous vasculitis can be classified into two types based on the affected vessel size: small vessel vasculitis predominantly affecting dermal venules, and muscular vessel vasculitis as found in cutaneous arteritis predominantly affecting arteries located at the dermal-subcutaneous junction. We describe two cases with a novel small vessel vasculitis disorder, which exclusively affected arterioles in the mid-dermis, and show clinical and pathological difference distinct from cutaneous polyarteritis nodosa and cutaneous venulitis. Both patients were male, and presented with painful infiltrative plaques, involving the palms, soles, and thighs without extracutaneous involvement except for fever and arthralgia. Histopathological examination revealed vasculitis in the mid-dermis characterized by a predominant infiltration of neutrophils with vessel wall fibrinoid necrosis and leukocytoclasia identical to the features of leukocytoclastic vasculitis, except that the affected vessels were arterioles rather than venules. Serological examinations showed normal levels of serum complements, immune complexes, and antineutrophil cytoplasmic antibodies, and vasculitis disorders associated with systemic diseases were excluded in both patients. The patients showed a good response to short-term treatment with prednisolone up to 30 mg. This novel cutaneous arteriolitis clinicopathologically different from both cutaneous venulitis and cutaneous arteritis appears to be a skin-limited disorder.