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Encapsulated papillary carcinoma of the breast: does it have a native basement membrane?

Ghannam, Suzan F; Rutland, Catrin S; Allegrucci, Cinzia; Mongan, Nigel P; Rakha, Emad

Encapsulated papillary carcinoma of the breast: does it have a native basement membrane? Thumbnail


Suzan F Ghannam

Professor of Breast Cancer Pathology


Encapsulated papillary carcinoma (EPC) is surrounded by a thick fibrous capsule-like structure, which is interpreted as a thickened basement membrane (BM). This study aimed to describe the geometric characteristics of the EPC capsule and to refine whether it is an expansion of the BM or a stromal reactive process.

Material and Methods
In all, 100 cases were divided into four groups: EPC, ductal carcinoma in situ (DCIS), normal breast tissue and invasive tumours, with an additional encapsulated papillary thyroid carcinoma (EPTC) control group. Representative slides from each case were stained with picrosirius red (PSR) stain and examined using polarised microscopy. Images were analysed using ImageJ, CT-FIRE, and Curve align image analysis programmes.

Compared to the normal and DCIS BM, the EPC group showed a significant increase of collagen fibre width, straightness, and density, and a decrease of fibre length. The EPC capsule showed less alignment of fibres with a more perpendicular arrangement, and it was enriched with disorganised collagen type I (stromal collagen) fibres. Compared to other groups, the EPC capsule showed significant variation in the thickness, evenness, distribution of collagen fibres, and significant intracapsular heterogeneity. Compared to BM-like material in the invasive group, the EPC capsule showed a higher density of collagen fibres with longer, straighter, and more aligned fibres, but there was no difference in the distribution of both collagen types I and III. Conversely, compared to EPTC, there were no differences between both EPC and EPTC capsules except that the fibres in the EPC capsule were straighter. Although differences between normal ducts and lobules and DCIS BM collagen fibre density, straightness, orientation, and alignment were detected, both were significantly different from EPC capsule.

This study provided evidence that the EPC capsule is a reactive process rather than a thickened native BM characteristic of normal and in situ lesions, which provides further evidence that EPC is an indolent invasive carcinoma based on capsule characteristics.


Ghannam, S. F., Rutland, C. S., Allegrucci, C., Mongan, N. P., & Rakha, E. (2023). Encapsulated papillary carcinoma of the breast: does it have a native basement membrane?. Histopathology, 83(3), 376-393.

Journal Article Type Article
Acceptance Date May 1, 2023
Online Publication Date May 26, 2023
Publication Date 2023-09
Deposit Date Jun 1, 2023
Publicly Available Date Jun 1, 2023
Journal Histopathology
Print ISSN 0309-0167
Electronic ISSN 1365-2559
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 83
Issue 3
Pages 376-393
Keywords breast cancer, Encapsulated papillary carcinoma (EPC), collagen, basement membrane (BM)
Public URL
Publisher URL
PMID 37232543


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