A 35-year-old woman who underwent a modified radical mastectomy of her right breast for infiltrating ductal carcinoma 2 years ago presents with enlargement of her right breast. The breast has a swollen, red-discolored appearance. It is diffusely indurated and tender on palpation. Multiple axillary lymph nodes are palpable in the lower axilla. The working clinical diagnosis is inflammatory carcinoma. Microscopic sections from this red, indurated area are most likely to reveal

Inflammatory breast carcinoma is often misunderstood because of the qualifying adjective inflammatory. The term does not refer to the presence of inflammatory cells, abscess, or any special histologic type of breast carcinoma; rather, it refers to more of a clinical phenomenon, in that the breast is swollen, erythematous, and indurated and demonstrates a marked increase in warmth. These changes are caused by widespread lymphatic and vascular permeation within the breast itself and in the deep dermis of the overlying skin by breast carcinoma cells. The clinical induration and erythema are presumably related to lymphatic-vascular blockage by tumor cells; if present, these findings mean a worse prognosis. Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition