Mammary Hamartoma
Definition
- Sharply circumscribed breast mass composed of normal or fibrocystic appearing tissue
Alternate/Historical Names
- Adenolipoma (variant)
- Choristoma
- Fibroadenolipoma
- Muscular or myoid hamartoma (variant)
Diagnostic Criteria
- Sharply circumscribed mass
- Nearly always palpable or radiographically distinct
- Composed of fibrous, fatty and glandular tissue
- Fibrous tissue may be dense and keloid-like
- Well formed ducts and lobules witih epithelial and myoepithelial cells
- Ducts may be cystic
- Lobules may be atrophic
- Normall peripheral distribution of myoepithelial cells
- Fat cells admixed
- If fat is predominant, lesion may be termed Adenolipoma
- No special clinical significance
- If fat is predominant, lesion may be termed Adenolipoma
- Appearance may be indistinguishable from fibrocystic change
- Circumscription is the only difference
- Cells with smooth muscle differentiation may be seen
- When smooth muscle cells are prominent, such lesions have been termed Myoid Hamartomas
- Smooth muscle cells may be spindled or epithelioid
- No special clinical significance
- When smooth muscle cells are prominent, such lesions have been termed Myoid Hamartomas
- Pseudoangiomatous stromal hyperplasia (PASH) has been reported in 25/35 mamary hamartomas
- Cartilage is rarely reported
- May be considered metaplasia in a hamartoma
- May be termed choristoma
- One report of brown fat
- Carcinoma has rarely been reported to involve mammary hamartomas
- Simlar findings have been reported in Cowden disease
- May be indistinguishable if circumscribed and solitary
- More common if diffuse or bilateral
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: May 15, 2006