Mammary Hamartoma
Differential Diagnosis
Nonspecific fibrocystic disease
- Mammary hamartoma is distinguished only based on its circumscription and formation of a discrete mass
| Adenomyoepithelioma |
Myoid Hamartoma |
| Myoepithelial component positive for keratin, p63, smooth muscle actin |
Myoid component positive only for smooth muscle actin |
| Tubules without lobules |
Well formed ducts and lobules |
| No admixed fat |
Admixed fat |
Cowden disease
- May be indistinguishable if circumscribed and solitary
- Diffuse or bilateral lesions favor Cowden disease
| Fibroadenoma |
Mammary Hamartoma |
| Lobules infrequent |
Lobules typically present (may be atrophic) |
| Frequent intracanalicular or tubular glandular proliferation |
Morphologically normal ducts and lobules |
| Intralesional fat rare |
Fat integral to lesion |
Both have keloidal fibrosis
Intramammary lipoma vs Adenolipoma
- Ducts and lobules prominent in adenolipoma
- Ducts and lobules rare or absent in lipoma
- No clinical significance to the distinction
