The comedo subtype of intraductal carcinoma. Cytologic characteristics

Smears from 10 intraductal carcinomas of the comedo type without microinfiltration were compared with smears from 10 similar tumors with suspected or proven microinfiltration and smears from 10 invasive comedo carcinomas. Microinvasive tumors could not be separated from purely intraductal cases unless tumor cell infiltration in mammary fat was seen in the smear. The tumor cells in most of the intraductal cases were shed in cohesive groups and clusters, lying in necrotic cellular debris and with few or no scattered, single, dissociated tumor cells. Smears from invasive comedo carcinomas invariably showed tumor cell clusters and scattered, single, dissociated tumor cells, often with atypia in excess of what was seen in the intraductal cases. Also, in most cases the invasive tumors did not show a background of necrotic cellular debris.