What is *not* a histological feature of invasive breast cancer?

Invasive breast cancer is characterized by several distinctive histological features that help pathologists diagnose and classify the tumor. Among these features, nuclear pleomorphism, vascular invasion, and coarse chromatin are all commonly observed in histological examinations of breast cancer.

Nuclear pleomorphism refers to variations in the size and shape of the nuclei of cancer cells, which is an indicator of the aggressive nature of the tumor. Vascular invasion, where cancer cells invade blood vessels, signifies a potential for metastasis, thus highlighting the invasive and malignant characteristics of the tumor. Coarse chromatin is another feature often seen in cancer cells; it presents as irregularly distributed chromatin patterns within the nucleus, further suggesting malignancy.

In contrast, metastatic calcification is not a histological feature specific to invasive breast cancer. Instead, it refers to the deposition of calcium salts in normal tissues due to an imbalance of calcium metabolism or mineralization, which can occur in various systemic conditions but is not a direct characteristic of the cancerous tissue itself. As a result, it does not play a role in the histological diagnosis and classification of invasive breast cancer.