A 51-year-old woman has noticed an area of swelling with tenderness in her right breast that has worsened over the past 2 months. On physical examination, the 7-cm area of erythematous skin is tender with a rough, firm surface resembling an orange peel. There is swelling of the right breast, nipple retraction, and right axillary non-tender lymphadenopathy. Excisional biopsy of skin and breast is most likely to show which of the following lesions?