Surgical Pathology Criteria

Microglandular Adenosis of the Breast

Differential Diagnosis

Tubular Carcinoma Microglandular Adenosis
Stellate, infiltrating Nodular or diffuse
Round to oval ducts with pointed ends and gaping lumens Uniform small round ducts with small lumens
Frequent apical snouts No apical snouts
Empty lumens Eosinophilic secretion present in at least some lumens
Larger cells, polarized to lumen Cells smaller, flatter
Round nuclei Nuclei may be flat, parallel to base
EMA positive EMA negative
Basement membrane absent Basement membrane variable
Both have rounded non-branching ducts with a single layer of cells, lacking myoepithelial cells


Sclerosing Adenosis Microglandular Adenosis
Prominent myoepithelial cells No myoepithelial cells
Cellular, sclerotic stroma Stroma collagenous or adipose
Lobular Haphazard
Compressed lumens Uniform round glands


Apocrine Adenosis Microglandular Adenosis
Myoepithelial layer present, may be hyperplastic No myoepithelial cells
Variable size and shape of glands Uniform round glands
Apocrine lumenal differentiation and in some cases squamous metaplasia present No squamous or apocrine metaplasia
EMA and GCDFP15 positive EMA and GCDFP15 negative


Microglandular Adenosis Tubular Adenosis
Uniformly round lumens Predominantly tubular
Cytoplasm frequently clear Cytoplasm eosinophilic
No myoepithelial layer Myoepithelial cells present
Secretion eosinophilic Secretion eosinophilic or basophilic


Microglandular Adenosis Tubular Adenoma
Poorly circumscribed pattern Circumscribed
Surrounds normal elements Mass displaces normal elements
No myoepithelial cell layer Myoepithelial cell layer present
Haphazardly scattered tubules Densely packed tubules
Abundant fibrous or fatty stroma Scant stroma

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