Pure tubular carcinomas have an excellent prognosis, due to low rates of lymph node metastasis and recurrence following complete excision. Tubular carcinoma may be confused with sclerosing adenosis. Sclerosing adenosis maintains a lobular architecture and the glands, although distorted by fibrosis, are lined by double cell layers consisting of both epithelial and myoepithelial cells. In contrast, tubular carcinoma infiltrates locally without lobular pattern and the glands are lined by a single layer of tumor cells. These tumors have lobulated borders, soft consistency and gelatinous cut surfaces, and may be confused with benign tumors, such as fibroadenoma.
Individual cells have low grade nuclear atypia.
Some cells have signet ring appearance. It typically occurs in the central portion of the breast as a round, 2-3 cm nodule with cystic change and hemorrhage. Complex papillary projections and cribriform glands consist almost entirely of epithelial cells without myoepithelial cells. Fibrovascular stalks are less prominent than benign intraductal papilloma. Tumor cells have low nuclear grade, inconspicuous nucleoli, and low mitotic activity.