A woman in her early 80s presented with a 6-month history of an asymptomatic, enlarging, partly infiltrated erythematous cutaneous patch localized to the periareolar area of her left breast (Figure, A). She had no history of cancer or chronic diseases. No cutaneous nodules were present. Physical examination did not show adenopathies, hepatosplenomegaly, or other remarkable findings. Peripheral blood test results were within normal limits. Tests for tumor markers including cancer antigen (CA) 15-3, carcinoembryonic antigen, CA 19-9, and CA 125 were unremarkable. No palpable breast masses were identifiable. Breast ultrasonography and mammography did not reveal parenchymal nodules. A local steroid therapy was administered, with no benefit. A biopsy of the skin lesion was performed (Figure, B and C).