Chilblains

Chilblains (pernio, perniosis) are localised inflammatory skin lesions caused by abnormal vascular response to cold, damp, non-freezing conditions. They affect the fingers, toes, ears, nose, and in some cases thighs and buttocks (riders and cyclists). The condition is commonest in young to middle aged women, thin people, smokers, and those with Raynaud phenomenon. It occurs in cold, humid climates and at high altitude in Kenya, such as the Aberdares, and in cold stores and refrigerator workers.

Mechanism: cold induced vasoconstriction followed by rewarming vasodilatation causes perivascular lymphocytic infiltrate, oedema, and fibrinoid change in dermal vessels. Idiopathic chilblains are self-limited, resolving in 1 to 3 weeks.

Secondary forms occur with lupus erythematosus (chilblain lupus), cryoglobulinaemia, cold agglutinins, chronic myelomonocytic leukaemia, anorexia nervosa, and interferonopathies (Aicardi-Goutieres, STING-associated vasculopathy), and acral lesions seen in COVID-19 ("COVID toes").

Recurrence is common each winter, and prognosis is good.

• Itchy, painful, red to purple macules, plaques or nodules, 0.5 to 3 cm, appearing 12 to 24 hours after cold exposure on toes, fingers, heels, ears and nose.
• Burning on warming, swelling, blistering, occasionally ulceration, and superficial desquamation.
• Chronic: persistent violaceous induration, fissures, atrophy, and scarring.
• Systemic symptoms are absent in idiopathic disease.
• Secondary features: arthralgia, rash, mouth ulcers, photosensitivity, Raynaud phenomenon, fever, weight loss, livedo, purpura.
• Red flags: ulceration, necrosis, fever, systemic symptoms, lesions persisting beyond 6 weeks, or onset in warm weather (suggests autoimmune or other disease).

• Clinical diagnosis based on typical lesions in a patient with cold exposure and no secondary cause.
• First line tests in persistent, recurrent or atypical cases: full blood count, ESR and C-reactive protein, glucose, renal and liver function, antinuclear antibody, anti-dsDNA, anti-Ro/La, antiphospholipid antibodies, complement, cryoglobulins (blood sample kept at 37 degrees C), cold agglutinins, and serum protein electrophoresis.
• Blood film and haematological review when there is cytopenia or monoclonal protein.
• Dermoscopy and nail fold capillaroscopy for associated Raynaud phenomenon or systemic sclerosis.
• Skin biopsy (4 mm punch from a fresh lesion) when diagnosis is uncertain or atypical: superficial and deep perivascular and perieccrine lymphocytic infiltrate, papillary dermal oedema, and vacuolar interface change; direct immunofluorescence for lupus band.
• Arterial Doppler or angiography only if peripheral arterial disease is suspected.
• Exclude frostbite, immersion foot, lupus pernio of sarcoidosis, Raynaud phenomenon, erythema multiforme, vasculitis, acrocyanosis, embolic disease, and cold urticaria.

• Cold protection is the cornerstone: warm, dry gloves and socks, insulated waterproof footwear, hat and scarf, avoid tight shoes and sudden rewarming with direct heat, avoid smoking and caffeine, and keep the home and workplace at 18 degrees C or above.
• Mild lesions: emollient twice daily, clean and dry skin; leave unbroken lesions uncovered. Topical corticosteroid, betamethasone valerate 0.1 percent or mometasone furoate 0.1 percent cream applied once daily for 7 days to unbroken, itchy lesions, then stopped; avoid on ulcerated skin.
• Vasodilator therapy for severe or recurrent disease: nifedipine modified release 20 mg orally twice daily (or 10 mg three times a day of the standard release) from the onset of lesions or for the whole cold season (usually 3 to 4 months); monitor for headache, flushing, dizziness, ankle oedema and hypotension; avoid in pregnancy.
• Alternatives: diltiazem 60 mg orally three times daily (or modified release 120 to 240 mg once daily), or amlodipine 5 mg once daily increased to 10 mg after 2 weeks.
• Pentoxifylline 400 mg orally three times daily for 3 months, or nicotinic acid derivatives are second line.
• Ulceration: topical antiseptic dressing; flucloxacillin 500 mg orally every 6 hours for 7 days when infected; analgesia with paracetamol 1 g every 6 hours; tetanus prophylaxis as needed.
• Refractory lesions: low dose sildenafil 25 mg orally twice daily for 3 months, or topical nitroglycerin 0.2 percent ointment applied thinly twice daily for 2 weeks (limit headache); hydroxychloroquine 200 mg orally twice daily for 6 months in chilblain lupus.
• Secondary disease: treat the cause (for example immunosuppression for lupus, treatment of haematological disease); withdraw offending drugs; nutritional rehabilitation in anorexia.
• Follow up: review at 2 to 3 weeks; assess for connective tissue disease at 6 to 12 months if first tests are normal but disease recurs or persists; annual review of recurrent cases.
• Counselling: lesions usually clear within 1 to 3 weeks; avoid scratching and rubbing; do not warm affected parts rapidly; prepare for the cold season with early use of vasodilators in those with previous severe disease.