Ash leaf spots (hypomelanotic macules): what they are and when they matter

The Tuberous Sclerosis Association describes hypomelanotic macules, often called ash leaf marks, as light marks of the skin that have less skin pigment and often resemble an ash leaf. They are flat patches rather than lumps, and they are paler than the surrounding skin rather than a different colour.

The TSA says they are found in up to nine out of every 10 people living with tuberous sclerosis complex and are usually present from birth. For that reason, when a doctor notices several ash leaf spots, it can prompt a closer look for TSC and for other features of the condition.

Because pale patches can be seen in other situations, a single mark on its own does not mean someone has TSC. The TSA describes the diagnosis as based on a combination of examinations, scans and other findings, not on one mark.

The TSA explains that TSC is a rare genetic condition that causes non-cancerous growths to develop in different organs of the body, such as the brain, eyes, heart and skin. A person is born with TSC, although problems might not be obvious until later in life.

Common problems can include epilepsy, autism, learning difficulties and kidney problems, but the TSA stresses that the way TSC affects a person varies considerably. Some people have few issues and may not know they have the condition, whereas others need much more specialist care and are diagnosed from birth. The TSA estimates that between 3,700 and 11,000 people in the UK live with TSC.

Ash leaf marks are one of several skin features the TSA describes. Skin problems usually start in childhood or the teenage years, and the biggest impact of skin marks is often psychological.

The TSA says a diagnosis usually follows careful physical examination combined with scans and imaging such as an MRI, and clinicians may use a checklist of characteristic features such as abnormal areas of skin or tumours in the eyes, brain, heart, lungs or kidneys. UK clinical guidelines for the diagnosis and management of TSC were released in 2018.

People suspected of having TSC might have an MRI scan of the brain, a CT scan of the lungs, liver and kidneys, an ultrasound of the kidneys, an echocardiogram, an eye examination, skin examination under ultraviolet light and genetic testing. The TSA says genetic testing is correct in around 80% of cases.

The TSA says clinicians will only confirm that a person has TSC if they are sure, through genetic testing or a range of scans and examinations. For skin problems specifically, a doctor does a painless test using a special light, sometimes called a Wood's lamp.

If you or your child have pale patches on the skin that were present from birth, or several such marks, particularly alongside seizures, developmental concerns or other unusual findings, it is reasonable to mention this to a GP. They can examine the skin and decide whether referral is needed.

The TSA notes that people are told they have TSC for many different reasons, such as lumps in the heart in a baby, seizures in a baby, marks on the skin, or problems with the kidneys as an adult, or because genes are tested. A new seizure, especially in a baby, needs urgent medical assessment.

The TSA says treatment options are available for TSC-related skin issues, including creams and ointments, laser therapy and surgery. It stresses that people with skin features take extra care in the sun, using suncream even on cloudy days, avoiding midday sun and wearing broad-brimmed hats.

The TSA says the biggest impact of skin marks is often psychological, and that the focus of care is on the wider condition and on any features that cause symptoms or distress.

After a diagnosis, the TSA says a clinician will possibly refer a person to a specialist TSC clinic and that follow-up scans and referrals to specialists such as a neurologist could take place. The TSA provides a support line and information for families, including a new diagnosis section.

The TSA says that thanks to improved understanding, the majority of people living with TSC can expect healthier lives with a normal life expectancy.

On the NHS, a GP or paediatrician can refer to dermatology, genetics or a specialist TSC clinic. The TSA publishes a list of NHS TSC clinics and a summary of the UK clinical guidelines that are used across them.

Private dermatology or genetic testing is possible, but because TSC affects several organs, coordinated follow-up through a specialist clinic matters more than any one test. Share private results with your GP and clinic.