Inflammatory plaque with peripheral nodules: a new specific finding of cutaneous polyarteritis nodosa

Cutaneous polyarteritis nodosa commonly affects the distal lower limbs, presenting as nodules, ulcers, and livedo reticularis. We report five cases to illustrate a new specific presentation of cutaneous polyarteritis nodosa on the trunk or proximal extremities. In the acute stage, lesions were tender erythematous plaques. On palpation, 1- to 2-cm diameter subcutaneous nodules were found along the periphery. The lesions responded to dapsone, aspirin, nonsteroidal antiinflammatory drugs, or systemic steroids and healed with postinflammatory hyperpigmentation. Systemic polyarteritis nodosa did not develop in any patient after a follow-up time ranging from 9 months to 9 years. The presence of small nodules at the periphery of an inflammatory plaque was a useful clinical clue, because this prompted us to suspect cutaneous polyarteritis nodosa when we encountered similar cases later, which could be confirmed histologically. In conclusion, cutaneous polyarteritis nodosa can present as inflammatory plaques on the trunk and proximal extremities, and the presence of peripheral nodules around these plaques constitutes a useful clinical clue to its diagnosis.