Invasive ductal carcinoma of the breast with a microglandular adenosis pattern.

Invasive breast carcinomas of special type are composed of up to 35% of all cases, such as tubular carcinoma, mucinous carcinoma, invasive cribriform carcinoma, lobular carcinoma, metaplastic carcinoma, medullary carcinoma, and other rare variants. They are recognized by their specific growth and morphologic patterns, glandular differentiation, and cytologic and nuclear features. These features are also present as a focal or minor component in many carcinomas of no special type. In addition, there are a number of lesions that are mimickers of invasive carcinoma, which can sometimes create diagnostic difficulties. It is important for pathologists to recognize these histologic variants and mimickers of breast carcinoma, particularly in evaluating needle or core biopsies. We report a case of a 64-year-old woman with breast carcinoma of no special type with areas having features with resemblance to microglandular adenosis. Differential diagnosis and their histologic features are discussed.