Hydroa vacciniforme: Skin disease due to sunlight exposure

Hydroa vacciniforme (hydroa aestevalis) is a skin disease in which the skin, especially of a child, reacts to sunlight. Recurrent fluid-filled blisters (hydroa) develop on sun-exposed skin areas. When these skin lesions heal, they leave behind pox-like scars. Furthermore, nail, eye and eye abnormalities are sometimes also possible. Various treatment options are available, such as medication and phototherapy. However, it is essential for the patient to protect themselves from sun exposure. In most patients, symptoms resolve by the time they reach adolescence. The outlook for the disease is good, although permanent scarring is possible.

  • Epidemiology of skin disease
  • Causes: Due to exposure to sunlight
  • Risk factors of skin disease
  • Symptoms: Burning, itching and stinging skin lesions
  • Diagnosis and examinations
  • Treatment of skin lesions
  • Sun protection
  • Medication
  • Phototherapy
  • Prognosis of hydroa vacciniforme
  • Complications of skin abnormality


Epidemiology of skin disease

Hydroa vacciniforme is a rare skin disease that mainly affects children between the ages of three and fifteen years. Children with a fair skin color are especially affected, but in the literature Asian children sometimes also suffer from the skin disease. Women are affected by the skin condition more often than men. Symptoms often start later in men than in women. In addition, the course of the disease is usually more severe and longer in men than in women.

Causes: Due to exposure to sunlight

Hydroa vacciniforme is a photodermatosis; a disease in which the skin reacts abnormally to exposure to sunlight. The precise cause of hydroa vacciniforme is usually not known. Some scientists report that hydroa vacciniforme is a more serious variant of polymorphic light eruption, also a skin disease that occurs after prolonged exposure to the harmful UV rays of sunlight.Exposure to the sun often causes the disease / Source: Blueeve, Pixabay

Risk factors of skin disease

Several risk factors are associated with the non-infectious condition. In fact, long-wavelength ultraviolet radiation (UVA) has been most commonly linked to the skin disease, but UVB light and visible light are also sometimes involved. Also, hydroa vacciniforme is occasionally associated with Epstein-Barr infection, which normally leads to glandular fever (infectious mononucleosis). Finally, a genetic predisposition may play a role in non-hereditary photodermatosis.

Symptoms: Burning, itching and stinging skin lesions

The rash usually first appears in the spring with recurrences occurring in the summer months. The parts exposed to the sun are most often affected. This concerns the face, ears, hands and lower limbs. When Epstein-Barr virus (glandular fever) is involved in the skin condition, the hydroa vacciniform lesions spread to areas not exposed to the sun. In most cases, symptoms start about thirty minutes to two hours after exposure.The skin disease is characterized by a mild burning, itching or stinging sensation in the affected skin areas. Furthermore, swelling in the face sometimes occurs. Patients with the disease also have tender, swollen bumps (papules) and fluid-filled blisters (vesicles) (sometimes even blood blisters) on the affected areas. These change into indented, pit-like papules with black crusts (necrosis) on a red and inflamed base. The lesions heal within a few weeks but leave pale scars.Other symptoms Some patients experience other symptoms, including mild inflammation of the eyes (keratoconjunctivitis and light sensitivity), loosening of fingernails and toenails (photoonycholysis). Occasionally, systemic signs such as headache, malaise (a general ill feeling) and fever also occur. Furthermore, many patients experience exaggerated reactions to insect bites resulting in skin necrosis and ulceration.

Diagnosis and examinations

Physical and diagnostic examination The doctor examines the symptoms present. He occasionally performs a UVA or UVB light test to trigger an outbreak of symptoms, but this method is usually not very reliable. The doctor will perform a skin biopsy to rule out other forms of sun allergy. Furthermore, a blood test is necessary, also to rule out infections and other diseases. The doctor often also uses a urine test and a stool test to rule out various types of porphyria.Differential diagnosis The doctor performs many tests because photodermatosis is reminiscent of the clinical picture of many other diseases, such as:

  • (photo) contact dermatitis (skin rash with redness and itching)
  • actinic prurigo (skin rash from sun exposure)
  • epidermolysis bullosa (skin conditions with blisters)
  • phytophotodermatitis (skin disease due to contact with plants)
  • herpes simplex
  • polymorphic light eruption (skin disease due to sun exposure)
  • blistering porphyrias (such as porphyria cutanea tarda, pseudoporphyria, erythropoietic protoporphyria, congenital erythropoietic protoporphyria, porphyria variegata, hereditary coproporphyria)
  • systemic lupus erythematosus
  • urticaria solaris (skin rash after exposure to UV rays)
  • chickenpox (infection with general symptoms and rash)
  • xeroderma pigmentosum (symptoms of skin, eyes and brain)
  • Hartnup disease (metabolic disease with skin rash)


Treatment of skin lesions

Sun protection

Patients with hydroa vacciniforme should take measures to avoid sun exposure or protect themselves from the sun’s ultraviolet rays. The patient therefore applies a protective sunscreen with UVA blockers with a protection factor of at least 50+. He also wears protective clothing and good sunglasses. This makes it possible to prevent or reduce the number of recurrences.


Oral (taken by mouth) medications are helpful in reducing new outbreaks, but it is not always possible to prevent hydroa vacciniforme lesions. The most common medications prescribed by the doctor are oral antimalarials such as hydroxychloroquine. Oral antioxidants such as beta-carotene can also be used. Furthermore, supportive treatment and good wound care are necessary for blisters and other skin lesions.


Phototherapy (light treatment) is also a useful treatment method that allows the skin to gradually get used to light, ultimately making the patient less sensitive.

Prognosis of hydroa vacciniforme

In most patients, the condition resolves by the time they reach adolescence. The pox-like scars are permanently present on the skin.

Complications of skin abnormality

A severe mononucleosis infection associated with hydroa vacciniforme may result in lymphoproliferative disorders (NK cell non-Hodgkin lymphoma or leukemia). The outcome is bleak.

read more

  • Skin damage due to exposure to UV radiation from the sun
  • Solar urticaria: Skin rash after exposure to UV rays
  • Sunlight: Benefits of moderate sun exposure
  • Sunburn: Red, painful skin due to sun exposure
  • Polymorphic light eruption: Skin disease due to sun exposure

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