Low Grade Adenosquamous Carcinoma of the Breast
Definition
- Low grade breast carcinoma exhibiting both glandular and squamous differentiation characterized by infiltrating, frequently compressed lumens
Alternate / Historical Names
- Metaplastic carcinoma
- Syringomatous squamous tumor
Diagnostic Criteria
- Infiltrating round to irregular tubules, often compressed and comma shaped
- Resembles syringoma
- Lumens may contain amorphous, eosinophilic material or keratin
- Myoepithelial cells prominently present around tubules
- Results in at least a double cell layer
- Squamous differentiation variable (5-80% of tubules)
- Overt keratinization less common than intercellular bridges
- Abundant collagenous stroma
- 2 of 32 cases reported with osteocartilaginous metaplasia of stroma
- Occasional lymphoid nodules present
- Bland cytology
- Mitotic figures rare
- No necrosis
- May be associated with other lesions
- 12/32 cases associated with intraductal papillary lesions
- 3/32 cases associated with adenomyoepithelioma
- 3/32 cases associated with collagenous spherulosis
- May be considered a low grade variant of metaplastic carcinoma or an adenomyomatous lesion
- It does not fulfil the strict definition of adenomyoepithelioma
- It has been proposed that this is the same lesion as infiltrating syringomatous adenoma of the nipple differing only in location
- Adenosquamous carcinoma rarely may metastasize but this has not been reported for syringomatous adenoma
Richard L Kempson MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting / updates: 5/1/06, 12/25/12