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.

7 Key points- Must know for boards about Secretory carcinoma breast

Here are 7 key points – Must know for pathology boards about secretory carcinoma of breast

Secretory carcinoma of breast in very rare. It harbours unique characteristics which aid in the diagnosis.

1. Secretory carcinoma was earlier known as juvenile breast cancer, but later renamed as secretory carcinoma of breast. This is the most common breast cancer occuring in children. However, it is reported in all age groups.

2. Microscopically, microcystic, tubular or solid pattern may be observed. A combination of the three is also frequent.

3. Intra and extra luminal secretions are present which are PAS- positive and diastase resistant.

Key points- Must know for boards about Secretory carcinoma breast1.Presence of microcystic,   solid or tubular pattern 2. PAS- Positive and  diastase resistant 3. ETV-6 NTR3 t(12;15)   is seen in these tumors 4. Common in children but can occur in all age groups 5. Often triple negative ( ER, PR and Her-2 negative)  6. Even though these tumors are triple negative- TP53 mutation is uncommon.  7. Lack gain of 1q and loss of 16q seen in low grade pathway
ETV6- NTRK3 fusion in secretory carcinoma of breast

4. Most tumors have translocation yielding ETV6-NTRK3 fusion gene ( t(12;15).

5. Secretory carcinoma of breast express triple negative molecular phenotype

6. Unlike most triple negative tumors which are TP53 mutant, srcretory carcinomas do not show TP53 mutation.

7. Secretory carcinomas also lack gain of 1q and 16 q loss, characteristic of the low grade tumorigenesis pathway.

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