How is papillary DCIS differentiated from small, peripheral intraductal papilloma (IDP)?

Updated: Dec 25, 2019
  • Author: Joshua I Warrick, MD; Chief Editor: Chandandeep Nagi, MD  more...
  • Print
Answer

Answer

In contrast to IDP (S/P ST), papillary DCIS usually has more delicate fibrovascular cores and is frequently involved by a clonal-appearing epithelial proliferation with mild to moderate cytologic atypia (see the following images). Most distinctively, however, papillary DCIS does not have a myoepithelial layer (see the 3rd and 6th images below). Immunostaining, therefore, can be useful in distinguishing between these 2 lesions. Many find it helpful to use a cytoplasmic marker, such as calponin or smooth muscle actin (SMA), along with the nuclear marker p63 (see Immunohistochemistry). It should be noted that occasional, scant expression of myoepithelial markers may be identified in papillary DCIS. This should not be taken as strong evidence of a benign papilloma if other features of the lesion favor papillary DCIS.

Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Papillary ductal carcinoma in situ (DCIS) (40×).
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Papillary ductal carcinoma in situ (DCIS) (200×). Several fibrovascular cores show delicate branching, and the epithelium shows moderate cytologic atypia.
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Papillary ductal carcinoma in situ (DCIS) (400×). Note the delicate fibrovascular cores and moderate cytologic atypia of the overlying epithelium. The epithelial cells directly abut the fibrovascular core, with no intervening myoepithelial layer (arrow).
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Papillary ductal carcinoma in situ (DCIS) (40×).
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Same papillary ductal carcinoma in situ (DCIS) as in the previous image (100×).
Pathology of small, peripheral intraductal papillo Pathology of small, peripheral intraductal papillomas. Same papillary ductal carcinoma in situ (DCIS) as in the previous two images (400×). The epithelial cells are moderately atypical and lie directly against the fibrovascular core without an intervening myoepithelial layer (arrow).

Cytokeratin (CK) expression also differs between IDP (S/P ST) and papillary DCIS in that CK5/6 and CK14 show stronger staining in IDP (S/P ST) than in papillary DCIS .

In a series by Tan et al, using a predetermined immunohistochemical cutoff score, the investigators were able to differentiate papillary DCIS from benign papilloma using CK5/6 and CK14 with a sensitivity of 95% and 85%, respectively, and a specificity of 86.8% and 94.3%, respectively. [22] The immunohistochemical score utilized percentage of cells stained multiplied by staining intensity, and both myoepithelial cell and epithelial cell staining was included in the evaluation. [22]

Tan et al's findings are similar to CK5/6 expression differences found between UDH and DCIS. [23, 24, 25, 26] However, it must be recognized that myoepithelial cells frequently express CK5/6 and CK14, and the staining differences between papilloma and papillary DCIS may largely be a result of the myoepithelial component of papilloma, and thus, they may not reflect differences in epithelial cytokeratin expression between IDP (S/P ST) and papillary DCIS.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!