What Do Aicardi-Goutières Syndrome Chilblains Look Like?

In Aicardi-Goutières syndrome (AGS), chilblains appear as painful, itchy, red or purple blister-like sores that develop on the body’s extremities, such as the fingers, toes, and ears ^[1][2]. Unlike typical chilblains that are simply caused by exposure to cold, damp conditions, the skin sores in AGS are the result of an overactive immune system attacking small blood vessels ^[2][3]. While cold weather is not the root cause, it can trigger a flare-up or make the sores worse ^[4][5].

What Do AGS Chilblains Look Like?

Recognizing chilblains early can help you manage discomfort and identify a potential disease flare. When checking the skin, you or your child may notice:

• Red or purple patches: The affected skin often looks inflamed, changing from red to a purplish or bluish tint (a condition called acrocyanosis) ^[6]. Acrocyanosis means the extremities turn blue or purple due to decreased blood flow.
• Swollen, blister-like sores: The skin may become raised, puffy, and resemble small blisters or solid bumps ^[1][2].
• Location: These lesions most commonly appear on the parts of the body furthest from the heart, including the fingers, toes, and ears ^[1][6].
• Nail changes: Over time, you might also see abnormalities such as splitting, pitting, or ridging in the nails on the affected fingers or toes ^[6].

Why Do They Happen?

AGS is known as an interferonopathy—a condition where the body produces too much interferon, a protein normally used by the immune system to fight viruses ^[2][7]. This high level of interferon causes the immune system to mistakenly attack healthy tissues, including the blood vessels in the skin ^[3]. The resulting inflammation damages these vessels, leading to the painful, itchy sores known as chilblains ^[7][2].

Managing Triggers and Treatment

Because AGS chilblains are driven by an underlying immune issue, managing them requires both practical care and medical treatment:

• Medical Treatments: Since the sores are caused by systemic inflammation, your doctor may recommend prescription treatments. This can include topical therapies to reduce local inflammation and itching, or systemic medications—such as JAK inhibitors—that target the overactive interferon pathway to help clear the skin lesions ^[8][9].
• Temperature Control: A drop in temperature can narrow the blood vessels and trigger a chilblain flare-up or increase pain ^[2][4]. Keep extremities warm with gloves, warm socks, and hats during cooler weather ^[5]. Avoid rapid temperature changes, such as running hot water over cold hands, as rapid rewarming can worsen inflammation and pain.
• Wound Care and Red Flags: If the blister-like sores break open, keep the area clean and covered to prevent secondary infections. Contact your medical team if the pain becomes unmanageable, if the sores ulcerate (become open wounds), or if you notice signs of infection such as increased redness, warmth, or pus.