A 60-year-old woman presented with a painless self-detected breast lump. After wide local excision, the histology of this radiologically suspicious lump turned out to be an inflammatory lesion with granulomatous foci, suggesting a diagnosis of granulomatous mastitis. Prior to the excision biopsy, this woman had suffered from and been treated for anterior uveitis, secretory otitis media, and proximal myopathy. Four weeks later, a skin biopsy of a rapidly developing widespread petechial rash, mainly affecting the lower limbs, confirmed the diagnosis as Wegener's granulomatosis. Treatment with intravenous steroids and later cyclophosphamide produced rapid remission.