Image of the Month 2010-2
Microglandular adenosis
Extensive infiltration by acinar structures with a single epithelial layer
and absent myoepithelium. The acinar structures frequently show contained eosinophilic secretion. This condition
is benign but it easily mistaken for tubular carcinoma. The clue is the fact that the acinar cells are either ER-poor
or negative - a very unusual finding in tubular carcinoma. The cells are also usually S100 positive.
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Negative CK5/6 immunostaining around adenosis acini. Note intact myoepithelial layer around normal duct on left.
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S100 immunostain showing strong nuclear staining of acinar structures. Note the normal duct in the centre of the picture which is negative.
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There is a large normal duct on the left/centre of this image with microglandular
adenosis surrounding it. The ER immunostain highlights: 1) the strong positive staining of many luminal epithelial
cells in the normal duct; 2) The negative staining for ER in the myoepithelail cells in the normal duct & 3)
Negative staining for ER in the microglandular acini.
Mouse over - Arrows point to myoepithelial layer; microglandular adenosis acini indicated with "A". Insert shows detail of ER staining in normal duct.