A lactating adenoma is a benign tumor which usually occurs in younger, pregnant and lactating women. It is a variant of a class of benign breast lesions called ‘fibroadenomas‘, which is essentially a pronounced growth of ducts and also the fibrous connective tissue including the glandular components. The development of fibroadenomas is often accompanied by the formation of cysts. A sub-category of fibroadenoma called ‘tubular adenoma‘ occurs when the tumor mostly consists of glandular tissue but with little stroma.
Lactating adenomas are essentially tubular adenomas which have occurred in pregnant or breast feeding women. The lesion often contains secretions of breast milk. Lactating adenomas are usually benign but in rare instances they can occur simultaneously with breast carcinoma, so they have to be carefully evaluated.
This page still has some helpful information, but a little bit outdated… however, go ahead and take a look at our new page on Lactating Adenoma, it is a bit more up-to-date!
Lactating adenomas are not a risk factor for breast cancer
A lactating adenoma lesion 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” caused by a blockage of the tissue’s blood supply). However, lactating adenomas on their own, are not a risk factor for breast cancer development in any way. Lactating adenomas may occur singularly or in multiples.
In the image of lactating adenomas below, 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 adenomca from a ‘galactocele‘, which 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 apparent radiologically 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 and this is often the key to a diagnosis. A few breast tumors can have misleading features such a microlobulated margins, irregular masses, and posterior acoustic shadowing which are suggestive of breast cancer. The confusing presentations are most commonly the result of infarction but a core needle biopsy is usually recommended just to be sure.
Treatment of lactating adenomas
Lactating adenomas are thought to arise from hormonal imbalances brought on by pregnancy and lactation. Following pregnancy and lactation, lactating adenomas will usually regress spontaneously, and often no additional treatment is necessary. But sometimes the patient is given bromocriptine or other dopamine agonist to help ‘shrink‘ the size of the tumor. This drug, however, will suppress lactation and may have other unanticipated side effects. If the lactating adenoma is thought to be a serious and inconvenient health problem, it may be surgically removed.
Let’s do some Q&A’s:
- What does lactating adenoma look like? A lactating adeonoma may present as a breast lump that feels either rubbery or firm and has a yellow to tan-color with a lobulated cut surface. A lactating adenoma often presents as a palpable mass that undergoes rapid growth and may be large in size.
- Do I have to stop breastfeeding? No.
- What is the cause of lactating adenoma? It is usually caused by hormonal changes during and after pregnancy. A lactating adenoma is more commonly found on breast self-exam 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? Due to the changes in the breast during pregnancy and breast feeding, such as breast engorgement, radiographic density is so increased that mammograms are often ineffective. The preferred method of imaging is ultrasound which can determine whether the breast lump is solid or cystic in nature. If the diagnosis is a solid mass, fine-needle aspiration is usually indicated but this method 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? A core biopsy is recommended for tissue sampling. Bromocriptine can be used to reduce the size of a lactating adenoma and works by suppressing prolactin levels.
- 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? Development of a milk fistula following needle core biopsy, and they can cause development of foci of infarction of breast tissue.
- What does the differential diagnosis include? Fibroadenoma, galactocoele (no color flow on ultrasound), breast lymphoma and phyllodes tumor.
- Is there an increased risk of breast cancer? No, lactating adenomas are not thought to carry any increased breast cancer risk . In effect, lactating adenomas are benign lesions. They are more common in pregnant women than in those breast feeding and often present as large, palpable breast masses.
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