Intraductal carcinoma (DCIS)

Cytological features of intraductal carcinoma (ductal carcinoma in situ, DCIS) vary according to whether a comedo or non-comedo type of DCIS is aspirated, the latter being characterized by intraductal necrosis.

DCIS, comedo type – cytological diagnostic features

Moderate to high cellularity
Loosely cohesive groups and single cells
Large pleomorphic cells
Abundant necrotic debris, histiocytes and occasional inflammatory cells

DCIS, noncomedo type – cytological diagnostic features

Moderate to high cellularity
Cohesive epithelial groups, sheets, clusters and papillary fragments
Mild to moderate uniform cellular atypia
No bipolar naked nuclei
Few to moderate number of atypical single cells

Surgical confirmation is required when atypical ductal hyperplasia (ADH) or DCIS, non-comedo type, is suggested by the cytological findings. It is usually believed that it is not possible to separate in situ from invasive carcinoma definitively by cytological examination, however smears from invasive carcinoma are generally more cellular, with a greater loss of cellular cohesion. Extensive necrosis associated with pleomorphic atypical cells is more often a feature of comedo-type DCIS than invasive ductal carcinoma, although large invasive carcinomas can show extensive necrosis. Breast malignancies of duct origin are generally reported as ductal carcinoma on smears, without specifying whether invasive or in situ carcinoma is present, this requires histological examination.