Q.Â I have a question regarding ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). I used to think that they were differentiated from each other by where they arise from (ie DCIS are from ducts and LCIS from lobules), however I have been told that this is not the case – that they both arise from the ‘terminal lobular ductal unit’. How are they different from each other then? Is it purely by the fact that the cells in LCIS are dyscohesive?
- DCIS is associated with calcification on mammography, LCIS is not. So LCIS is almost always an incidental finding; you can’t see it on mammography.
- LCIS is often bilateral; DCIS is usually unilateral.
- Microscopically, the cells look different in DCIS and LCIS. The cells in LCIS are dyscohesive, like you mentioned. They are round and they don’t hang together in architectural patterns. The image on the bottom is of LCIS; note how the cells grow in solid groups. The cells in DCIS, on the other hand, can form all kinds of structures (papillae, or little cookie cutter spaces, or micropapillae).Â The image on the top is of DCIS, and there’s a nice cribriform pattern in the lobule at 5 o’clock.