[220] Infiltrative Epitheliosis of the Breast: Clinicopathological Review of Seven Cases of "Pseudoinfiltrative Epitheliosis"

MJ Horne, N Buza, FA Tavassoli. Yale-New Haven Hospital, New Haven, CT

Background: Infiltrative epitheliosis is a distinct breast lesion characterized by a pseudoinfiltrative proliferation of small cords of epithelial and/or often myoepithelial cells emanating from ducts with various patterns of epithelial proliferation into adjacent stroma. It may be associated with complex sclerosing lesions and it has been included in the spectrum of radial scar, despite its distinctive features. It is important to recognize this entity since it may be mistaken for invasive carcinoma particulary on core biopsies. A modified term - “pseudo-infiltrative epitheliosis” (PE) - is proposed to emphasize its benign nature and to avoid unnecessary additional surgery.
Design: Seven cases were retrieved from our institutional database in a two-year period (1/2007 to 9/2009) that included PE in the final diagnosis. Five of the cases were pulled from one of the author's personal consultation files. All H&E and immunohistochemical slides (including CK903, CK5/6, p63, calponin), and available clinical and radiological information were reviewed.
Results: All patients were female, with a mean age of 44.7 years (range: 27-61). Five of the specimens were lumpectomies, one was a mastectomy, and one case was diagnosed on mammotome biopsy. Three patients presented with a mass lesion, one patient had an area of enhancement on MRI, and in two patients PE was the secondary finding in a mastectomy performed for a known malignancy. Two consultation cases had been diagnosed as malignant by the primary pathologist and were determined to be benign PE on review. One case was submitted for consultation with a diagnosis of extensive papillomatosis and was found to have areas of PE admixed with infiltrating ductal carcinoma.
Conclusions: The pseudo-infiltrative pattern of epithelial and myoepithelial cells in PE mimics an invasive process, and may be easily misdiagnosed especially on smaller biopsy specimens. Confirmation of persistent epithelial and myoepithelial cell layers or pure myoepithelial cells on immunostains in association with papillomas or low risk epithelial proliferation rather than higher grade ductal intraepithelial neoplasia are helpful in supporting a benign process. However, the presence of PE does not rule out carcinoma as the two were intermixed in one of the cases reviewed. The term infiltrative epitheliosis may be confusing and may provoke unnecessary anxiety in patients and clinicians. Therefore, we propose using the term pseudo-infiltrative epitheliosis for this benign entity.
Category: Breast

Monday, March 22, 2010 1:00 PM

Poster Session II # 38, Monday Afternoon


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