Humpath.com - Human pathology

Home > E. Pathology by systems > Reproductive system > Female genital system > Breast > mammary medullary carcinoma

mammary medullary carcinoma

Tuesday 12 October 2004

medullary breast carcinoma; medullary carcinoma of the breast

WP

Definition: Medullary carcinomas of the breast make up less than 5% of all breast carcinomas. They seen in younger age group (usually under age 50). It is more common in Japanese women and in carriers of BRCA1 mutations.

Medullary carcinoma shows a prominent lymphoplasmacytic infiltrate and is well circumscribed. It is associated with BRCA-1, is triple negative, and has a relatively good prognosis.

Medullary carcinoma is associated with BRCA-1 mutations and is triple negative for ER, PR and Her-2. It has a relatively good prognosis even though it is a poorly differentiated tumor.

Microscopically, it shows a prominent lymphoplasmacytic infiltrate and is well circumscribed. A well circumscribed malignancy with a lymphoplasmacytic infiltrate is consistent with medullary carcinoma.

Images

- http://www.webpathology.com/image.asp?case=298&n=1

Digital case

- JRC:5032 : medullary carcinoma of the breast.
- JRC:5034 : medullary carcinoma of the breast.

Grossly, they are usually bulky tumors, often reaching 5-6 cm in size. The tumors are soft, well-circumscribed, and have smooth periphery. The cut surface often bulges above the surrounding tissue. Areas of hemorrhage and necrosis are quite common and may lead to cystic degeneration (as seen here).

An intact medullary carcinoma with a firm, discrete appearance may be mistaken grossly for a fibroadenoma, however, it lacks the trabeculation and whorled appearance.

Medullary carcinoma is associated with BRCA-1 mutations and is triple negative for ER, PR and Her-2. It has a relatively good prognosis. Microscopically, it shows a prominent lymphoplasmacytic infiltrate and is well circumscribed.

Microscopy

Medullary carcinoma shows a diffuse growth pattern with no glandular differentiation or intraductal component. The tumor cells have high-grade nuclei and abundant eosinophilic cytoplasm. They are arranged in broad sheets, nests, or anastomosing trabeculae. The cytoplasmic borders are indistinct creating a syncytial appearance.

A characteristic feature is the presence of a prominent lympho-plasmacytic infiltrate within and around the tumor. Lymphoplasmacytic infiltrate is apparent at the periphery of the tumor cell clusters.

The tumor cells have abundant eosinophilic cytoplasm (with a hint of squamous differentiation), large pleomorphic nuclei, prominent nucleoli, and frequent mitoses. Indistinct cell borders create a syncytial appearance.

Microscopically, the borders of medullary carcinoma are smooth, rounded, and of "pushing type". The border tends to push aside the breast parenchyma and fat rather than infiltrating it. Non-neoplastic glands and fat are therefore not seen within the main body of the tumor.

In contrast, the borders of an infiltrating ductal carcinoma can have medullary features. The tumor borders freely infiltrate into the surrounding fat.

Lympho-plasmacytic reaction surrounds clusters of tumor cells, some of which are multinucleated and highly pleomorphic. The appearance can resemble a lymphoepithelioma-like carcinoma.

IHC

Medullary carcinoma is positive for E-cadherin and beta-catenin - it has stronger expression of E-cadherin and beta-catenin than high grade ductal carcinomas.

Differential diagnosis

The diagnosis of medullary carcinoma of breast rests on a constellation of histopathologic features, including non-infiltrating microscopic circumscription of tumor borders, prominent lympho-plasmacytic reaction, syncytial growth, high nuclear grade, and high mitotic rate. When defined strictly by these criteria, the tumors have favorable prognosis.

When some but not all of these features are present, the tumor may be called infiltrating ductal carcinoma with medullary features (or atypical medullary carcinoma).

However, the precise diagnostic criteria for making such a diagnosis have not been fully defined.

See also

- mammary carcinomas

References

- Eichhorn JH. Medullary carcinoma, provocative now as then. Semin Diagn Pathol. 2004 Feb;21(1):65-73. PMID: 15074561