Details
Breast mass.
This is an example of a well differentiated invasive ductal carcinoma (IDC) of no special type (not otherwise specified). Overall, IDC is the most common type of breast cancer, which is found by palpable mass (especially in patients younger than 40 years), or by screening.
Special types of IDC recognized by WHO are: tubular carcinoma, cribriform carcinoma, apocrine carcinoma, mucinous carcinoma, micropapillary/papillary carcinoma, medullary-like carcinoma and metaplastic carcinoma. If over 90% of a tumour is composed of a single special type, it is labelled as such. If it is between 50-90%, it is labelled as a mixed tumour.
Although IDC have been previously divided into subtypes based on morphology and IHC pattern (ER, PR, HER2), molecular subtyping based on gene expression profile has also become available. Commercial testing (such as Oncotype DC) is also available to predict response of ER positive cancers to chemotherapy.
Reporting requirement is standardized and published by College of American Pathologists Cancer Protocol Templates (see related content).