Phytophotodermatitis

The Phytophotodermatitis or photo- dermatitis is inflammation of the skin caused by certain plant extracts ( furanocoumarins ) and subsequent irradiation is caused by UV -A. In contrast to sunburn the disease is prolonged and causes a strong pigmentation after healing.

Frequency

The disease occurs mainly in the period from early summer to autumn. It affects people who deal professionally or in their free time with plants and are then exposed to the sun. People of all skin types can be affected regardless of the strength of previous browning.

Disease mechanism

The Phytophotodermatitis is a phototoxic skin reaction. Skin coming from the outside ( or, rarely, via the bloodstream ) into contact with a photosensitizer that absorbs light energy and transfers to neighboring molecules. The wavelengths of light are triggering in the UV -A region or in the visible range.

Triggering substances

Most triggering substances originate from the group of psoralens ( furocoumarins ) and in leaves, stems and fruit stands of native or exotic plants contain. These include:

  • Parsnip ( Pastinaca )
  • Giant hogweed ( Heracleum mantegazzianum )
  • Hogweed ( Heracleum sphondylium )
  • Meisterwurz ( Peucedanum ostruthium )
  • Angelica (Angelica )
  • Fig tree (Ficus carica )
  • Rue ( Ruta graveolens )
  • Bergamot (Citrus bergamia )
  • Cartilage carrot ( for example, cartilage Big Carrot )
  • Celery ( Apium graveolens )

Some of these plants are also processed in drinks ( herbal liqueur ), spices or perfumes, and can also trigger this way a phototoxic reaction.

Photosensitizers are also contained in coal tar, certain medications can trigger photodermatitis:

  • 3,5 - and 8 -methoxypsoralen
  • Phenothiazines, especially chlorpromazine
  • Tetracyclines, especially Dimethylchlortetrazykline
  • Certain NSAIDs
  • Alendronate, a bisphosphonate.

Clinic

One to two days after plant contact and exposure to the sun can be found in striated sheet-like or net-like patterns arranged lesions, corresponding to the points of contact with the plants or their cut surfaces. In addition, due to the necessary exposure to sunlight, the spread on the body - typically on the arms and legs. There appear redness and blisters that reach their peak after about three days. The patients report itching and burning pain. Under strong hyperpigmentation skin symptoms heal after two to four weeks.

With only weak sun exposure, the strong inflammatory reaction may be absent and after one to two weeks immediately hyperpigmentation occur ( Photodermatitis pigmentaria or Berloque dermatitis).

Diagnosis and differential diagnosis

The striped arrangement and the shape of the skin with redness and blistering phenomena allows the diagnosis and allows the differential diagnosis of sunburn.

In contrast to porphyria cutanea tarda the Porphyrinwerte are normal.

Therapy

The treatment is carried out locally with creams and lotions that contain glucocorticoids. In severe cases, can also be achieved with systemic glucocorticoid administration a relief. Prostaglandin inhibitors are ineffective.

Forecast

Disease cures after two to four weeks, leaving a strong pigmentation that may remain for many months. The treatment has - apart from the acute symptoms - no significant influence on the course.

Literature and sources

  • Ernst G. Jung ( ed.): dermatology. 2nd revised and enlarged edition. Hippocrates Verlag, Stuttgart 1991, ISBN 3-7773-1021-2.
  • Radiation-induced disease
  • Skin disease
Biological pigment Phototoxicity Masterwort Bergamot orange Medical diagnosis
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