Breast, Invasive lobular carcinoma

Invasive lobular carcinoma is the most common special type of breast carcinoma (2nd most common classification overall) which is typically composed of discohesive cells arranged singly or in files. Other architectural patterns include solid, alveolar, or tubulo-lobular arrangements. Classic type lobular carcinoma usually has low grade nuclear features, in contrast to the pleomorphic variety which can show high grade nuclei. Loss of e-cadherin (a transmembrane protein associated with intercellular adhesion) expression is frequently associated with these lesions, although demonstration of such by immunohistochemistry is not absolutely necessary for diagnosis. The typical breast biomarker profile of these lesions is ER/PR positive, HER2 negative.

This case shows both classic invasive and in situ components.