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Medullary carcinoma of the breast is a rare subtype of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it), accounting for about 1-2% of all cases of breast cancer. It is called “medullary” carcinoma because the tumour is a soft, fleshy mass that resembles a part of the brain called the medulla.
Medullary Carcinoma:
Medullary carcinoma of the breast is a rare subtype of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it), accounting for about 1-2% of all cases of breast cancer. It is called “medullary” carcinoma because the tumour is a soft, fleshy mass that resembles a part of the brain called the medulla.
Medullary Carcinoma:
This special type of infiltrating breast cancer has a rather well-defined boundary between tumour tissue and normal tissue. It also has some other special features, including the large size of the cancer cells and the presence of immune system cells at the edges of the tumour.
Medullary carcinoma accounts for about 1-2% of breast cancers. The outlook (prognosis) for this kind of breast cancer is generally better than for the more common types of invasive breast cancer. Most cancer specialists think that true medullary cancer is very rare, and that cancers that are called medullary cancer should be treated as the usual invasive ductal breast cancer.
Medullary carcinoma can occur at any age, but it usually affects women in their late 40s and early 50s. Medullary carcinoma is more common in women who have a BRCA1 mutation. Studies have shown that medullary carcinoma is also more common in Japan than in North America.
Medullary carcinoma cells are usually high-grade in their appearance and low-grade in their behavior. In other words, they look like aggressive, highly abnormal cancer cells, but they don’t act like them. Medullary carcinoma doesn’t grow quickly and usually doesn’t spread outside the breast to the lymph nodes. For this reason, it’s typically easier to treat than other types of breast cancer.
Diagnosis:
Like other types of breast cancer, medullary carcinoma may not cause any symptoms at first. Over time, a lump can form, and unlike most invasive ductal carcinomas the mass is often soft and fleshy or somewhat spongy to the touch. Most medullary carcinomas are small — less than 2 cm in size. Medullary carcinoma may be the cause of pain, swelling, redness, or tenderness in the breast. Because of the soft homogeneous mass medullary Ca is not always easy to detect with either BSE or CBE.
Tests that obtain images of the tissue inside the breast, such as mammography and ultrasound, can help identify a medullary carcinoma. On these tests, medullary carcinoma appears as a small, well-defined mass. However, because of its well defined, smooth, well circumscribed nature, mammography alone is not always reliable at determining medullary carcinomas as a malignant process.
Diagnosing medullary carcinoma usually involves a combination of steps:
Medullary carcinoma accounts for about 1-2% of breast cancers. The outlook (prognosis) for this kind of breast cancer is generally better than for the more common types of invasive breast cancer. Most cancer specialists think that true medullary cancer is very rare, and that cancers that are called medullary cancer should be treated as the usual invasive ductal breast cancer.
Medullary carcinoma can occur at any age, but it usually affects women in their late 40s and early 50s. Medullary carcinoma is more common in women who have a BRCA1 mutation. Studies have shown that medullary carcinoma is also more common in Japan than in North America.
Medullary carcinoma cells are usually high-grade in their appearance and low-grade in their behavior. In other words, they look like aggressive, highly abnormal cancer cells, but they don’t act like them. Medullary carcinoma doesn’t grow quickly and usually doesn’t spread outside the breast to the lymph nodes. For this reason, it’s typically easier to treat than other types of breast cancer.
Diagnosis:
Like other types of breast cancer, medullary carcinoma may not cause any symptoms at first. Over time, a lump can form, and unlike most invasive ductal carcinomas the mass is often soft and fleshy or somewhat spongy to the touch. Most medullary carcinomas are small — less than 2 cm in size. Medullary carcinoma may be the cause of pain, swelling, redness, or tenderness in the breast. Because of the soft homogeneous mass medullary Ca is not always easy to detect with either BSE or CBE.
Tests that obtain images of the tissue inside the breast, such as mammography and ultrasound, can help identify a medullary carcinoma. On these tests, medullary carcinoma appears as a small, well-defined mass. However, because of its well defined, smooth, well circumscribed nature, mammography alone is not always reliable at determining medullary carcinomas as a malignant process.
Diagnosing medullary carcinoma usually involves a combination of steps:
- A physical examination of the breasts. The mass created, although soft and homogenous, may be detected and dealt with.
- A mammogram to triangulate and examine any existing mass and check for evidence of cancer in other areas of the breast.
- Ultrasound to obtain additional images of the mass and check for other areas of cancer.
Biopsy, either surgical or large core, is the key to accurate diagnosis of medullary Ca, because imaging tests alone have difficulty differentiating between medullary carcinoma, benign processes and other types of breast cancer.
Gross description of Medullary Carcinoma tumours
- Well circumscribed, often large, resembles fibroadenoma but without whorls
- Soft, fleshy, tan-gray
- No desmoplasia, easy to cut, large areas of necrosis and hemorrhage
Images of Tumours diagnosed as Medullary Ca
Figure1: Sharply defined margin with internal nodularity and bosselated surface.
Figure2: Grey fleshy tumour
Figure3: Well circumscribed
Figure 4: Smooth, well-circumscribed border, homogeneous with no fibrous stroma
Figure 5: smooth 7cm tumour
Microscopic description
When looked at under a microscope, medullary carcinoma has a number of important features that a pathologist looks for:
If the tumour has all of these features, it is considered to be a “true” medullary carcinoma. Sometimes the tumour has only some of these features but not others, or there may be some invasive ductal carcinoma cells mixed in. In these cases, the tumour is “atypical medullary carcinoma.”
When looked at under a microscope, medullary carcinoma has a number of important features that a pathologist looks for:
- A clear, well-defined boundary between tumour tissue and normal breast tissue. Medullary carcinoma pushes against the surrounding healthy tissue, but doesn’t grow into it in the same way invasive ductal carcinoma usually does.
- Large-sized cancer cells with a high-grade appearance, meaning that they look very different from normal, healthy breast cells. However, medullary carcinoma cells do not behave like high-grade cancer cells, which are aggressive and grow and spread quickly. Medullary cancer cells also tend to blend together in a distinctive “sheet like” pattern; it’s hard to see each cell’s individual membrane (outer lining).
- Immune system cells (white blood cells called lymphocytes and plasma cells) at the edges of the tumour. Immune system cells work to fight off diseases and any substances they see as a threat to the body. It’s believed that these cells help keep the medullary carcinoma in check, preventing it from growing and spreading quickly.
If the tumour has all of these features, it is considered to be a “true” medullary carcinoma. Sometimes the tumour has only some of these features but not others, or there may be some invasive ductal carcinoma cells mixed in. In these cases, the tumour is “atypical medullary carcinoma.”
High grade tumor cells with syncytial pattern of cells
More distinct cell borders
Clusters of sheets of syncytial cells with prominent lymphoplasmacytic infiltrate
Various images of typical medullary Ca
Lymphocytes in micro papillary and medullary carcinomas
There are some other key features of medullary carcinoma:
- Hormone-receptor-negative: Medullary carcinoma usually tests negative for hormone receptors.
- HER2-negative: Medullary carcinoma also usually tests negative for receptors for the protein HER2/neu.
- (1) Indistinct cell borders (syncytial growth) making up 75%+ of tumor with large pleomorphic tumor cells containing large nuclei, prominent nucleoli, numerous mitotic figures; peripheral cells are more eosinophilic
- (2) Prominent lymphoplasmacytic infiltrate at periphery composed of T cells and IgA plasma cells
- (3) Pushing borders / well circumscribed
- Classify as medullary carcinoma if tumor has above three features
- Classify as atypical medullary carcinoma (or infiltrating ductal carcinoma) if tumor has only 2 of 3 features listed above (atypical medullary carcinoma has similar prognosis as ductal carcinoma NOS)
Other features:
- Sparse stroma
- Variable spindle cell or squamous metaplasia, occasional bizarre tumor giant cells and extensive necrosis
- No/minimal glandular differentiation, no intraductal growth or DCIS, no mucin, no calcification
Atypical medullary carcinoma
Figure 1: Atypical tumour invades fat and is not well circumscribed
Figure 2: Typical tumour includes poorly differentiated nuclei, syncytial growth, lymphoplasmacytic infiltrate
Figure 3: Tumour is infiltrative
We are the ‘thin pink line’ that stands as a protection against ignorance, a source of pertinent breast health information and as a foundation for the start of treatment or diagnosis. We have the chance to be the voice of reason, to dispel myth and present fact. The more we know about signs and symptoms that affect our patients the better professionals we become.
Power is knowledge; the truth is much less scary than myth, story and insinuation.
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