Invasive Micropapillary Carcinoma of the Breast
Differential Diagnosis
- Usual infiltrating carcinoma with retraction artifact
- Usual infiltrating carcinoma with extensive lymphovascular invasion
- Mucinous carcinoma
- Metastatic micropapillary carcinoma of other site
Usual infiltrating carcinoma with retraction artifact
- Retraction artifact usually occurs with dense stroma
- Micropapillary carcinoma is characterized by:
- Fine fibrocollagenous stroma
- Uniformity and density of pattern in involved areas
Usual infiltrating carcinoma with extensive lymphovascular invasion
- Lymphovascular invasion is delimited by CD31 positive endothelial cells
- Micropapillary carcinoma is characterized by:
- Lack of surrounding endothelium
- Uniformity and density of pattern in involved areas
| Mucinous Carcinoma | Micropapillary Carcinoma |
|---|---|
| Prominent mucin in spaces | Spaces generally clear with infrequent, scant stainable mucin |
| Irregular epithelial clusters | Numerous, relatively uniform clusters, one or a few per space |
| Usually low grade cytology | Frequently high grade cytology |
Immunohistochemistry of micropapillary carcinomas of various sites
| CK7 | CK20 | GCDFP15 | ER | PR | TTF1 | |
|---|---|---|---|---|---|---|
| Bladder | 100% | 90% | ND | ND | ND | ND |
| Breast | 83% | 0% | 50% | 20-90% | 20-90% | ND |
| Large Intestine | 0% | 100% | ND | ND | ND | ND |
| Lung | 93% | 13% | ND | ND | ND | 80% |
| Salivary Gland | 100% | 0% | 83% | 8% | 8% | ND |
| Ovary | 100% | 15% | <5% | 100% | 90% | 1% |
- Identification of adjacent DCIS strongly supports a breast primary
- Clinical information and imaging studies will frequently be necessary to rule out other primary sites.
