New breast lump: why imaging is needed (cyst versus solid tumour)
A new breast lump can be a cyst (a fluid-filled sac) or a solid tumour, and examination cannot reliably tell them apart, so imaging is needed.
Remember
A smooth, mobile feel does not make a breast lump benign: anyone aged 30 or over with an unexplained lump (one with no clear benign explanation) is referred on the suspected cancer pathway for imaging.
A cyst is a fluid-filled sac, often surrounded by fibrous (scar-like, supportive) tissue. It usually feels smooth and mobile, and cysts commonly present between the ages of 35 and 50. A cyst is usually benign.
Touch alone cannot be trusted to tell a cyst from a solid lump. A cyst can feel firm, and a solid tumour can feel smooth and mobile, so examination alone cannot reliably tell them apart. A smooth, mobile feel does not make a lump benign.
Imaging separates the two. Ultrasound (a scan that uses sound waves) shows whether a lump is fluid-filled or solid, and cysts are rarely cancerous. At the breast clinic the lump is imaged with ultrasound or mammography (an X-ray of the breast), depending on age and breast density. A needle biopsy (a small sample of tissue) is added if needed.
NICE advises that anyone aged 30 or over with an unexplained breast lump, with or without pain, is referred on the suspected cancer pathway. This is a fast-track route to a specialist breast clinic for people who might have cancer, and it does not mean the lump has already been diagnosed as cancer. Under 30, NICE advises considering a non-urgent referral.
If imaging confirms a cyst that is causing symptoms, it can be aspirated (drained with a fine needle) for relief. Surgical removal of a cyst is rarely required.
Key facts
- Breast cyst
- a fluid-filled sac that is usually benign.
- Typical feel
- smooth and mobile, although a cyst can also feel firm.
- Limit of examination
- touch alone cannot reliably tell a cyst from a solid lump.
- Imaging
- ultrasound tells cystic from solid, and cysts are rarely cancerous.
- Referral rule
- an unexplained breast lump in anyone aged 30 or over, with or without pain, goes on the suspected cancer pathway.
- Watch and wait
- only mastitis (infection of the breast) that settles, and fibrocystic change (changes in the breast that include cysts) that is without doubt cyclical (it follows the menstrual cycle), may avoid referral; a new single lump that does not vary with the cycle does not fit fibrocystic change.
Exam traps
- Watching and waiting to see whether a new unexplained lump settles is wrong at 30 or over, because an unexplained breast lump at that age needs a breast clinic referral rather than a wait in primary care.
- Aspirating a new lump in the GP surgery to see whether it holds fluid is off-target as the next step, because imaging at the breast clinic should separate cyst from solid tissue first, before a needle is used.
- A routine, non-urgent referral is too slow for a new unexplained breast lump at 30 or over, which warrants the suspected cancer pathway, because a non-urgent wait could delay the imaging and biopsy that a possible cancer needs.
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