Periarteritis nodosa presenting as a breast lesion: report of a case and review of the literature.

We describe a 34-year-old woman with periarteritis nodosa (PAN) presenting as a breast lesion. Localized involvement of the breast is an unusual manifestation of PAN. To date, 10 cases have been reported: all were in women with an age range of 45-78 years (mean 63). In most cases, breast lesions were an isolated finding, and the prognosis was favourable, setting them apart from the more common form of systemic PAN. The case presented is unusual in that vasculitis developed in the postpartum period, and was associated with cutaneous PAN-like lesions elsewhere on the body, and digital artery occlusion. The most important differential diagnoses of PAN of the breast are infectious mastitis, mammary malignancy and other forms of idiopathic vasculitides of the breast, e.g. giant cell arteritis and Wegener granulomatosis.