RESUMEN
We report a case of a 76-year-old woman, presenting with a persistent dry cough, subfebrility, arthralgia and myalgia, weight loss and a breast lesion. She has elevated inflammatory parameters, impaired renal function with proteinuria, bilateral lung nodules on computed tomography scan (CT scan) and a suspect lesion on mammography. A diagnosis of microscopic polyangiitis with involvement of the breast is made based on clinical and radiographic findings, with positive auto-immune serology and histological confirmation. Although vasculitis of the breast is uncommon, this case illustrates that when a breast lesion is found, in combination with constitutional symptoms, we should think about the possibility of an anti-Neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis. Therefore it may be important to perform auto-immune serology in these cases before proceeding to major surgery.