Introduction

Ductal carcinoma in situ (DCIS) is a noninvasive condition. DCIS can progress to invasive cancer, but estimates of the probability of this vary widely. Some reports include DCIS in breast cancer statistics. In 2025, DCIS is expected to account for about 16% of all newly diagnosed invasive plus noninvasive breast tumors in the United States.[1] For invasive and noninvasive tumors detected by screening, DCIS accounts for approximately 25% of all cases.

The frequency of a DCIS diagnosis has increased markedly in the United States since the use of screening mammography became widespread. Very few cases of DCIS present as a palpable mass, with more than 90% being diagnosed by mammography alone.[2]

DCIS comprises a heterogeneous group of histopathological lesions that have been classified into the following subtypes primarily because of architectural pattern:

Comedo-type DCIS consists of cells that appear cytologically malignant, with the presence of high-grade nuclei, pleomorphism, and abundant central luminal necrosis. Comedo-type DCIS appears to be more aggressive, with a higher probability of associated invasive ductal carcinoma.[3]