Breast Cancer - Moose and Doc

A breast cancer explanations website

 

By Dr. Halls

Lactating Adenoma

A lactating adenoma is a benign tumor. This type of breast lump usually occurs in younger, pregnant and lactating women.

This tumor is a variant of a class of benign breast lesions called ‘fibroadenomas‘.   

The typical features of this group of lesions include a pronounced growth of ducts and fibrous connective tissue including the glandular components.

The formation of cysts often accompanies the development of fibroadenomas.   There is a sub-category of fibroadenoma  ‘tubular adenoma‘  that occurs when the tumor mainly consists of glandular tissue but with little stroma.

So, lactating adenomas are essentially tubular adenomas that occur in pregnant or breastfeeding women.

The lesion often contains secretions of breast milk.   Lactating adenomas are usually benign.  However, in very rare cases, lactating adenomas can occur together with breast carcinoma.

Because of this medics need to carefully evaluate lactating adenomas.

This page has some helpful information.  However, we have a  new page on benign hyperplasia, including lactating adenomas.  So, go ahead and take a look.

Lactating adenomas are not a risk factor for breast cancer

A lactating adenoma will often appear in a lobular, non-capsulated shape, with well-circumscribed margins.  Some lactating adenomas will have evidence of infarction (a process of tissue death). “Necrosis” is caused by a blockage of the tissue’s blood supply.

lactating-adenoma-cytology-1

However, lactating adenomas on their own, are not a risk factor for breast cancer in any way.

Lactating adenomas may occur singularly or in multiples.

In the image of lactating adenomas to the right, one notes clusters of hyperplasic (newly developed) ducts and dilated lumen containing milk secretions.

The presence of so many new ducts would distinguish a lactating adenoma from a ‘galactocele‘. A galactocele is essentially a build of up milk secretions due to blocked ducts, but with no new tissue growth.

Lactating adenoma may mimic a malignant tumor

A lactating adenoma is usually quite obvious on a mammogram as they tend to have the same regular shape and well-defined margins of fibroadenomas.

The secretory milk by-products will usually show up as ‘fat’ on both mammography and ultrasound. So, this is often the key to a diagnosis.

A few of these  breast tumors can have misleading features such as:-

  • microlobulated margins
  • irregular masses
  • posterior acoustic shadowing

All of the above can be suggestive of breast cancer. The confusing presentations are most commonly the result of infarction. However, a core needle biopsy is usually necessary, just to be sure.

Treatment of lactating adenomas

Specialists think that hormonal imbalance, due to pregnancy and breastfeeding, is the main cause of lactating adenomas.

Following pregnancy and breastfeeding, lactating adenomas will usually clear up by themselves. Furthermore, often no additional treatment is necessary.

However, sometimes the treating physician will prescribe  bromocriptine, or another dopamine agonist, to help ‘shrink’ the size of the tumor.

However, this drug can suppress milk production and may have other side effects. If the lactating adenoma is thought to be a serious and inconvenient health problem, surgical removal may be necessary.

Let’s do some Q&A’s:

What does lactating adenoma look like?

A lactating adenoma may present as a breast lump that feels either rubbery or firm. Often they will have a yellow to tan-color with a  lobulated cut surface.  A lactating adenoma often presents as a palpable mass that grows quickly and so may be large in size.

Do I have to stop breastfeeding?

No. Usually, there is no reason to stop breastfeeding and nothing too serious to worry about.

What is the cause of lactating adenoma?

Hormonal changes during and after pregnancy are the cause of lactating adenoma.  Often, women will find a lactating adenoma on breast self-examination during the third trimester of pregnancy.

Are lactating adenomas painful?

No. They are usually painless.

How will a breast lump during pregnancy or breast feeding be investigated?

So, mammograms are often not effective due to the changes in the breast because of breast enlargement due to breastfeeding.

Thus, many doctors prefer to use ultrasound. Furthermore, an ultrasound scan can also determine whether a breast lump is solid or cystic in nature. Whether a lump is solid or liquid filled is important for diagnosis.

If the lump turns out to be a solid mass, fine-needle aspiration is usually necessary.  However, ultrasound has been related to some false negative and positive results in lactating adenomas.

Therefore, ultrasound-guided core biopsy is often the method of choice for diagnosis.

What is the lactating adenoma treatment?

Medics will recommend a core biopsy for tissue sampling.

In addition, doctors may prescribe the drug Bromocriptine to reduce the size of a lactating adenoma.  This drug works by suppressing prolactin levels. However, the pros and cons need to be carefully balanced in breastfeeding mums as the drug may stop milk production.

Surgical removal may be the best option.

What part of the breast does lactating adenoma occur?

There may be a predilection towards the anterior portion of the breast.

What are the complications?

So, there are no real complications of the lactating adenoma in and of itself. However, obviously, breast swelling and a lump can cause a lot of emotional stress for a pregnant or new mum.

Furthermore, the development of a milk fistula after a needle core biopsy is unusual but possible.

What does the differential diagnosis include?

Is there an increased risk of breast cancer?

No, please don’t worry. Lactating adenomas are not thought to carry any increase to the risk for breast cancer. 

In effect, lactating adenomas are benign lesions.   They are most common in pregnant women, although they do occur in breastfeeding women too.

So, just to summarise, lactating adenomas present as large, palpable breast masses.

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About Steven Halls

Dr Halls has 25 years experience as a radiologist. He worked for 13 years at Cross Cancer Institute in Edmonton, a world-class cancer treatment facility. He has had high-volume experience with cancer, interventional procedures, clinical trials and his own phase 1 and 2 research in MRI and breast cancer staging.