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 |
