[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Breast](https://durgical.com/en/general-pathology/areas/breast/) › Invasive breast carcinoma: special types

# Invasive breast carcinoma: special types

- Lesion

Some breast cancers have a distinctive pattern that predicts their behaviour: some are kinder than usual, others spread in unusual ways.

Updated Nov 12, 2026

## Key points

- Lobular: single-file and targetoid infiltration, discohesive cells, signet-ring forms; E-cadherin negative; ER-positive; often bilateral or multicentric and hard to see on mammography.
- Lobular carcinoma metastasises to unusual sites: peritoneum, retroperitoneum, leptomeninges, gastrointestinal tract, ovaries, uterus and bone marrow.
- Tubular: angulated tubules lined by a single layer of cells; ER-positive; excellent prognosis.
- Mucinous (colloid): clusters of cells floating in pools of extracellular mucin; older women; soft gelatinous tumour; good prognosis.
- Medullary pattern: syncytial sheets of high-grade cells, pushing borders, heavy lymphoplasmacytic infiltrate; triple-negative, BRCA1-associated.
- Metaplastic: squamous or mesenchymal (spindle, chondroid) differentiation; triple-negative; poor prognosis. Micropapillary: lymphovascular invasion and nodes.

On this page

- The basics Key points
- What it is
- Structure
- Step by step
- Special types of invasive breast carcinoma
- Markers
- Memory aid
- Elsewhere in DurgiPedia

- Clinical Clinical notes

- Study Test yourself

- Connections Connections

## What it is

About a quarter of invasive breast carcinomas show a special histologic pattern that carries prognostic meaning. Invasive lobular carcinoma, the most common special type, grows in single files because it has lost E-cadherin and spreads to unusual sites. Tubular and mucinous carcinomas are ER-positive and have an excellent prognosis. The medullary pattern, now grouped with tumours rich in lymphocytes, is triple-negative but does better than its grade suggests. Metaplastic and micropapillary carcinomas behave aggressively, while secretory and adenoid cystic carcinomas are rare and indolent.

## Structure

- Lobular: small uniform cells in single files and concentric rings around ducts; stroma little altered.
- Mucinous: lakes of mucin occupying most of the tumour with small floating nests.
- Micropapillary: hollow clusters of cells with inside-out polarity in empty spaces.
- Apocrine: large cells with abundant granular pink cytoplasm, androgen receptor positive.

## Step by step

- Loss of E-cadherin (CDH1) frees lobular cells from each other, so they infiltrate one by one.
- Single discohesive cells form little desmoplasia, so the tumour may be felt as thickening rather than a lump.
- Other special types reflect particular programs: abundant mucin secretion, well-formed tubules, or epithelial-mesenchymal transition in metaplastic carcinoma.
- Fusion genes drive rare indolent types: ETV6-NTRK3 in secretory carcinoma, MYB-NFIB in adenoid cystic carcinoma.

## Special types of invasive breast carcinoma

| Type | Key feature | Receptors | Prognosis |
| --- | --- | --- | --- |
| [Invasive lobular](https://durgical.com/en/conditions/breast-cancer/) | Single files, E-cadherin loss | ER-positive | Similar to no special type; unusual metastatic sites |
| Tubular | Angulated single-layer tubules | ER-positive | Excellent |
| Mucinous | Cells floating in mucin | ER-positive | Good |
| Medullary pattern (lymphocyte-rich) | Syncytial sheets, pushing border, lymphocytes | Triple-negative | Better than expected for grade |
| Metaplastic | Squamous or mesenchymal elements | Triple-negative | Poor |
| Invasive micropapillary | Inside-out clusters in clear spaces | Usually ER-positive | Frequent node metastases |
| Secretory | Secretions, ETV6-NTRK3 fusion | Triple-negative | Good |
| Adenoid cystic | Cribriform glands, MYB-NFIB fusion | Triple-negative | Excellent |

## Markers

- E-cadherin (negative in lobular)
- Androgen receptor (apocrine)
- Pan-TRK (secretory)
- MYB (adenoid cystic)

## Clinical notes

- Lobular carcinoma can present with peritoneal, ovarian, gastric or meningeal metastases years after the primary.
- Recognising favourable types such as tubular and mucinous carcinoma can spare some patients aggressive treatment.
- Triple-negative is not always aggressive: secretory and adenoid cystic carcinomas are exceptions.

## Memory aid

Lobular walks in single file and turns up in strange places; tubular and mucinous are the polite guests; metaplastic is the shape-shifter.

## Test yourself

Think of the answer, then tap the question to see it.

## Why does invasive lobular carcinoma grow in single files?

Its cells have lost E-cadherin, so they do not adhere to one another.

## Which special types have an excellent prognosis?

Tubular, mucinous, secretory and adenoid cystic carcinomas.

## To which unusual sites does lobular carcinoma metastasise?

Peritoneum, retroperitoneum, leptomeninges, gastrointestinal tract, ovaries, uterus and bone marrow.

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## Elsewhere in DurgiPedia

- [Breast: ducts, lobules and changes with life stage](https://durgical.com/en/histology/breast-ducts-lobules-and-changes-with-life-stage/)

## Connections

## Related 7

- [Invasive breast carcinoma of no special type](https://durgical.com/en/general-pathology/invasive-breast-carcinoma-of-no-special-type/)
- [Lobular carcinoma in situ](https://durgical.com/en/general-pathology/lobular-carcinoma-in-situ/)
- [Sporadic breast cancer: molecular subtypes](https://durgical.com/en/general-pathology/sporadic-breast-cancer-molecular-subtypes/)
- [Familial breast cancer: BRCA1, BRCA2 and others](https://durgical.com/en/general-pathology/familial-breast-cancer-brca1-brca2-and-others/)
- [Metastases to the ovary](https://durgical.com/en/general-pathology/metastases-to-the-ovary/)
- [Immunohistochemistry: the principle and the markers to know](https://durgical.com/en/general-pathology/immunohistochemistry-the-principle-and-the-markers-to-know/)
- [Pathways of spread and the usual metastatic sites](https://durgical.com/en/general-pathology/pathways-of-spread-and-the-usual-metastatic-sites/)

## Related conditions 2

- [Breast cancer](https://durgical.com/en/conditions/breast-cancer/)
- [Hereditary breast and ovarian cancer syndrome (BRCA1/BRCA2)](https://durgical.com/en/conditions/hereditary-breast-and-ovarian-cancer-syndrome/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Breast Cancer Treatment (PDQ®)–Health Professional Version](https://www.cancer.gov/types/breast/hp/breast-treatment-pdq) (National Cancer Institute, 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/invasive-breast-carcinoma-special-types/