Breast tissue

Breast cancer can develop in the small amount of tissue behind the nipples.

Cross-section of male chest

The diagram shows a cross-section of a man’s chest, including the layer of breast tissue in front of the muscle and ribs.
Image: The diagram shows a cross-section of a man’s chest from the side. Behind the nipple is a small layer of breast tissue. Behind the breast tissue is a layer of muscle, then some of the ribs of the chest.

Until puberty, breast tissue in boys and girls is the same. They both have a small amount of breast tissue behind the nipple and areola (the darker area of skin around the nipple). This is made up of a few tiny tubes (ducts) surrounded by fatty tissue, connective tissue, blood vessels and lymphatic vessels.

At puberty, boys and girls both start to produce the hormone oestrogen. In girls, this leads to breast tissue developing. In some boys, oestrogen causes breast swelling. But this is usually temporary and the breast tissue does not develop. At the same time, boys start making more of the hormone testosterone. This acts against the effects of oestrogen.

The balance of these hormones can be affected as men get older, or as a side effect of certain drugs. Other health conditions can also affect the hormone balance, such as chronic liver disease, obesity and an overactive thyroid gland (hyperthyroidism). This can cause breast tissue to swell in men. This is called gynaecomastia. It is not linked to breast cancer. If you are worried about any changes, talk to your GP.

What is the lymphatic system?

The lymphatic system helps protect us from infection and disease. It is made up of fine tubes called lymphatic vessels. These vessels connect to groups of small lymph nodes throughout the body. The lymphatic system drains lymph fluid from the tissues of the body before returning it to the blood.

Lymph nodes are sometimes called lymph glands. They filter bacteria (germs) and disease from the lymph fluid. When you have an infection, some lymph nodes may swell as they fight the infection.

Breast cancer and the lymph nodes

Sometimes cancer can spread through the lymphatic system. If breast cancer cells spread outside the breast, they are most likely to go to lymph nodes in the armpit. You will usually have tests to look for cancer cells in the lymph nodes. There are also lymph nodes near the breastbone and above the collarbone.

The lymph nodes near the breast

The diagram shows a man’s chest and the lymph nodes in the armpit area, above the collarbone and near the breastbone.
Image: The diagram shows a man’s chest, shoulders and upper body. The lymph nodes are shown on the right side of the chest. The lymph nodes are shown as about 30 bean-shaped dots. They are connected by a network of lines. These are lymph vessels. This network runs from the right side of the neck, through the collarbone area and upper chest. One branch of the network runs to the right armpit area and outer side of the right breast. Another branch runs down the centre of the chest to the inner side of the right breast.

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About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Dr Rebecca Roylance, Consultant Medical Oncologist and Professor Mike Dixon, Professor of Surgery and Consultant Breast Surgeon.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
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We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 October 2023
Next review: 01 October 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.