Micropapillary breast carcinoma is a rare variant.

Micropapillary carcinoma of breast has a few unique clinical, microscopic and immunological features which aid in their differentiation from other subtypes of breast carcinoma.

Let’s look at them!!

1. Tufts of cells arranged in pseudopapillae ( lack fibrovascular cores). These pseudopapillae are surrounded by empty clear spaces formed by fibrocollagenous stroma.

Micropapillary breast carcinoma- microscopy

2. Aggressive tumor usually present with angiolymphatic invasion. They present with nodal invasion at the time of presentation.

3. Molecular and cytogenetics: BC-1514 (C21orf118) is commonly upregulated in the micropapillary area.

4. ER positive in 90% and PR positive in 50%

5. Micropapillary breast carcinomas show

‘INSIDE OUT’ staining pattern with EMA and CD15s.

INSIDE OUT staining pattern refers to – staining localized to the apical surface of tumor cells abutting the stroma but absent staining in the basolateral region.

Staining pattern of EMA ( Epithelial membrane antigen) and CD 15s in micropapillary breast carcinoma.

6. Another characteristic of micropapillary breast carcinoma is Incomplete basolateral or CUP SHAPED staining with apical sparing seen with E- cadherin,  Her-2-neu and p-120.

‘Cup shaped’ staining with EMA – stained basolateral surface and apical sparing.

Below is a picture which will help you remember all characteristics of micropapillary breast carcinoma.


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