Tag Archives: ADH

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Breast – Atypical Ductal Hyperplasia (ADH)

ADH is a neoplastic proliferation that shares some characteristics of ductal carcinoma in situ (DCIS), but falls short quantitatively or qualitatively.  ADH is associated with a moderately increased risk of developing an invasive breast carcinoma (4-5x relative risk, 13-17% lifetime risk).
 
The morphology is similar to DCIS, but the findings do not entirely fill the duct spaces and/or don’t fulfill a quantitative size requirement for DCIS (some require 2 mm lesion).  In biopsy specimens it is important to perform an excision biopsy/lumpectomy because approximately 1/3rd of cases will have an associated higher grade lesion in the immediate vicinity (e.g. DCIS or an invasive carcinoma). 
Breast lesions and risk of developing an invasive carcinoma
Relative
Risk
Absolute
Risk
(lifetime)
Breast
Lesion
1
3%
1.5 – 2
5-7%
4 – 5
13-17%
8 – 10
25-30%
References

Robbins, p. 1050-1051

Organ Systems, IHC Panels

Breast – UDH vs. ADH

A common differential diagnosis in breast lesions is between usual type hyperplasia (UDH) and atypical ductal hyperplasia (ADH)/ductal carcinoma in situ (DCIS).  In difficult cases there are some immunohistochemical patterns, which may be helpful to differentiate between diagnoses.  UDH has  mosaic expression pattern with HMWK  (high molecular weight keratins) (e.g. CK5 or CK5/6) whereas ADH/DCIS typically does not.  ADH/DCIS does typically has strong uniform up regulation of estrogen receptor (ER) in contrast to UDH.
 
DIAGNOSTIC FEATURES
Cellular Population
Florid UDH
ADH
True hyperplasia contains a mixture of cell types (streaming, slit-like spaces)
Clonal population of monotonous cells with rigid “punched-out” spaces
 
CK Expression
Florid UDH
ADH
Mixture of basal cells (CK5/14/17) and luminal cells (CK7/8/18)
Monotonous population of luminal cell types (CK 7/8/18)
 
ER Expression
Florid UDH
ADH
Variable patchy expression
Usually uniform strong expression
 
Breast Cancer Relative Risk
Florid UDH
ADH
Slightly increased (1.5-2 X)
Moderately increased (3.7-5.3 X)
 
 
Diagnostic Features
Florid UDH
ADH
Cellular Population
True hyperplasia contains a mixture of cell types (streaming, slit-like spaces)
Clonal population of monotonous cells with rigid “punched-out” spaces
CK Expression
Mixture of basal cells (CK5/14/17) and luminal cells (CK7/8/18)
Monotonous population of luminal cell types (CK 7/8/18)
EP Expression
Variable patchy expression
Usually uniform strong expression
Breast Cancer R.R.
Slightly increased (1.5-2X)
Moderately increased (3.7-5.3X)

 

References
Hicks DG. Immunohistochemistry in the diagnostic evaluation of breast lesions. Appl Immunohistochem Mol Morphol. 2011;19(6):501–505. doi:10.1097/PAI.0b013e31822c8a48.
 
Liu H. Application of immunohistochemistry in breast pathology: a review and update. Arch Pathol Lab Med. 2014;138(12):1629–1642. doi:10.5858/arpa.2014-0094-RA.