What causes atypical papilloma and ductal carcinoma in situ (DCIS)?

Updated: Jun 18, 2020
  • Author: Oudai Hassan, MD; Chief Editor: Chandandeep Nagi, MD  more...
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The authors of this article believe that most cases of ductal carcinoma in situ (DCIS) involving an intraductal papilloma (IDP) (L/C ST) result from the direct extension of independent DCIS into an adjacent IDP (L/C ST). This is based on the knowledge that DCIS is known to primarily arise from the terminal duct lobular unit (TDLU), while IDP (L/C ST) is known to arise from the ducts proximal to the TDLU. [5]

In addition, many cases of DCIS involving a papilloma are seen in association with ADH/DCIS in adjacent ductal spaces. [1] Therefore, it stands to reason that most cases of DCIS involving a papilloma are collision tumors. However, rare cases have been seen in which a focus of definite DCIS was seen in an IDP, and no other DCIS could be found on thorough examination of the surrounding breast tissue. These cases may represent DCIS arising from the epithelium of the IDP.

DCIS may also involve small peripheral (S/P ST) IDPs. These cases may represent a form of collision tumor or alternatively may represent DCIS and IDP (S/P ST) arising from the same TDLU.

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