The clinical and pathologic features of a case of giant cell arteritis presenting in the breast and those of seven previously reported similar cases are described. A unique finding in the present case was a coincidental in situ and infiltrating ductal carcinoma in the same biopsy specimen. All the patients were postmenopausal women who presented with a firm mass in one or both breasts that mimicked a carcinoma on physical examination. There was no definite clinical evidence of temporal artery involvement in any patient, and two patients had normal temporal arteries on histologic examination. Five patients, however, had systemic manifestations, arteritis in another site, or both. Giant cell arteritis presenting in the breast may occur as an isolated finding or represent a manifestation of more widespread disease.