Other sclerosing lesions:
Sclerosing adenosis
- Usually incidental but may be a mass lesion
- Often associated calcs - picked up on screening
- May be confused with cancers histologically
- Low power view critical to make correct diagnosis.....
- note the nodular arrangement of crowded acini
- The edge of a focus may be apparently infiltrative but less so than many low grade carcinomas
- At high power the glands are very crowded and may be cytologically atypical
- Around some glands at least you should be able to see a compressed myoepithelial layer
- Immunostaining shows an intact myoepithelial layer e.g. with CK 5/6
Low power view of a focus of sclerosing adenosis (blue circle) - the background lesion has a vaguely stellate architecture and it is
likely that in this case the focus of sclerosing adenosis was part of an early radial scar
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Medium power views of a focus of sclerosing adenosis
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Low power view of two adjacent nodular foci of sclerosing adenosis
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Medium power view of one of the nodules above
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Immunohistochemistry for CK 5/6 showing preservation of myoepithelial layer throghout area of sclerosing adenosis
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Unusual variant of sclerosing adenosis - note prominent 'myoid' differentiation of myoepithelial cells demonstrated clearly by smooth muscle actin imunostain
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Atypical apocrine sclerosing lesion
- Sclerosing adenosis lesion with superimposed apocrine metaplasia
- Atypia may be moderately severe - distinction from apocrine DCIS (with lobular cancerisation) may be difficult
- Immunostaining will demonstrate an intact myoepithelial layer and basement membrane
- Follow up of patients showed no greater cancer risk than other atypical lesions
- The example below is from a large lesion with the architecture of a radial scar - much smaller microscopic lesions may also be seen
Atypical apocrine sclerosing lesion
Note overall pattern of a radial scar with superimposed apocrine metaplasia
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Atypical apocrine sclerosing lesion - detail showing crowded glands with apocrine atypia
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Atypical apocrine sclerosing lesion - CK 5/6 staining highlights overall lobular pattern (left); detail (right)
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Microglandular adenosis
- Pseudo-infiltrative lesion that may be mistaken for carcinoma
- Glands lined by a monolayer of bland epithelial cells
- Lumens contain PAS positive secretory material
- Myoepithelial layer absent but dense basement membrane present
- Epithelial layer stains strongly positive with S100
- Probable increased risk of subsequent carcinoma - follow up recommended
Microglandular adenosis - low power view showing haphazard arrangement of glands apparently infiltrating stroma
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Microglandular adenosis - ducts lined by a single epithelial cell layer and conaining secretory material. Stroma is non-reactive
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