Medullary carcinoma of the breast

Medullary carcinoma of the breast (MCB) is an uncommon subtype subtype of breast cancer and accounts for ~5% ^1,4 of all breast cancers.

Epidemiology

They tend to occur more frequently in younger women than other breast cancer types ⁷. The mean age of presentation varies from 46-54 years but in 10% of cases theymay present in women under 35 years.

Clinical presentation

Clinically, these tumours are characterised by rapid growth and therefore often manifest as palpable masses. Lesions can be quite large at presentation.

Pathology

A MCB typically arises from supporting stromal cells of the breast ³. The World Health Organization (WHO) criteria for diagnosis are “a well circumscribed carcinoma composed of poorly differentiated cells with scant stroma and prominent lymphoid infiltration”. Large pleomorphic nuclei prominent nucleoli and high mitotic activity may be seen. The histologic appearance of medullary carcinoma can mimic that of poorly differentiated intra ductal carcinoma not otherwise specified. Areas of associated necrosis may be present. In familial form of breast cancer with BRCA1 gene mutation medullary and mucinous cancers are more common.

There are two types of MCB:

• typical type: has to meet with the following criteria
  • a) syncytial growth pattern of poorly differentiated tumor cells with a high mitotic rate
  • b) prominent lymphoplasmacytic reaction with a circumscribed microscopic appearance-inflammatory reaction must involve 75% of the periphery and must be present diffusely throughout the substance of the tumor
  • c) no glandular or fatty breast tissue should be found within the invasive portion of the tumour
• atypical type: resembles the usual classic case; it must have at least 75% syncytial growth but does not have the other two features (circumscription and lymphoplasmacytic infiltration)

Many medullary carcinomas tend to be oestrogen and progesterone receptor negative.

Radiographic features

Mammography

Typically seen as a circular/ oval/oval type mass mass lesion with ill-defined or circumscribed margins at mammography. There can be varying degrees of lobulation while calcification is usuallynot a feature.

Breast ultrasound

The mass can be either homogeneously hypo-echoichyperechoic or hypo-echoichypoechoic with mild heterogeneity ^1-2. Enhanced through transmission may be present ². The level of hypo-echogenicity can sometimes be marked ⁸. 

Breast MRI

May show diffuse enhancement post contrast.

PrognosisTreatment and prognosis

The prognosis tends to be better than for intraductal carcinoma (NOS).