Photodermatology deals with the diagnosis of idiopathic light dermatoses (the causes of which have not yet been clarified), light-induced dermatoses (which are worsened by light) and the treatment of various inflammatory and malignant skin diseases. Light dermatoses include polymorphic light dermatosis (PLD), chronic actinic dermatitis (CAD), light urticaria, prophyrias, systemic photoallergic and phototoxic dermatoses and photoallergic and phototoxic contact dermatitis. The example of photoallergies in particular illustrates the close links between the Light Department and the Allergy Outpatient Clinic. Both functional areas, as well as all other functional areas, work hand in hand (see illustration).

Diseases aggravated (worsened) by UV radiation already manifest themselves without increased exposure to light (UV), but are exacerbated after exposure to UV radiation. These include lupus erythematosus (butterfly lichen), herpes simplex recidivans in loco (cold sores) and atopic dermatitis, which is rarely light-aggravated, to name but a few. The following diseases can usually be successfully treated with the help of differentiated phototherapy: Psoriasis vulgaris (psoriasis), all forms of dyshidrosiform, toxic-degenerative chronic hand eczema in which fungal disease and allergy have been ruled out, atopic dermatitis, pityriasis lichenoides acuta/chronica, pityriasis rosea (rose lichen), exanthematic lichen ruber (nodular lichen), pruritus (itching) in various underlying diseases or idiopathic genesis, Vitiligo (white spot disease), localised scleroderma (morphea), lichen sclerosus et atrophicus, forms of necrobiosis lipoidica, granuloma anulare, some forms of skin sarcoidosis, T-cell lymphomas of the skin (mycosis fungoides), mastocytosis of the skin (urticaria pigmentosa), graft-versus-host disease after bone marrow transplants and numerous other diseases. The various irradiation sources are subject to regular quality control (dosimetry, spectral analysis) in order to minimise the long-term side effects of UV irradiation. Patients are informed in detail about all side effects and light protection and are given a UV passport in which the irradiation modality and the respective irradiated dose are precisely documented. Patients who have been exposed to UV radiation for a long time are examined regularly (prevention programme).

Carrying out the light staircase to determine the patient's sensitivity in the UVA and UVB range before UV therapy

• Carrying out the minimum phototoxic dose before PUVA therapy.
• Photoprovocations for the diagnosis of polymorphic light dermatosis, photoallergies.
• Wavelength-dependent induction of light dermatoses using a monochromator.

The following irradiation modalities are routinely carried out in Ulm Photodermatology:
UVB irradiation using selective UVB spectra to minimise harmful side effects. We have sources with spectra 290-320nm and 311-313nm with iso-dose irradiation (same dose on the abdomen and lower legs so that the dermatoses heal at the same time). Used for psoriasis vulgaris, pityriasis rosea, vitiligo (also Juhlin scheme), lichen ruber, etc.
A UVB comb is available for psoriasis of the head.
This therapy is initially carried out daily (Mon-Fri) with increasing doses for between 4 and 8 weeks, depending on the clinic and disease. Combination therapies with UVB, vitamin D preparations, cignolin, topical and systemic retinoids, etc. are also carried out.

UVA irradiation is carried out using sources that emit the entire UVA spectrum (320-400nm) or selective UVA spectra (UVA1, 340-400nm). With the selective UVA1 spectrum in particular, higher doses can be used and we also have medium-dose and high-dose UVA1 irradiation available for the treatment of refractory atopic dermatitis and urticaria pigmentosa.
In the treatment of atopic dermatitis and pruritus, these UVA sources are also used in combination (simultaneously) with UVB irradiation.
These therapy modalities are carried out daily (Mon-Fri) between 4-8 weeks.

PUVA (psoralen + UVA) therapy modalities. In systematic PUVA therapy, Psoralene (Meladinine, Geralene) is administered in tablet form. Two hours later, the patient is irradiated with UVA. Psoralene makes the patient's skin and eyes more sensitive to UVA radiation. On the one hand, this is desirable for treating the skin disease, but on the other hand, the patient must wear protective goggles even after PUVA therapy and avoid exposure to the sun. This form of therapy is used for urticaria pigmentosa, light urticaria and T-cell lymphoma of the skin (here in combination with retinoids or interferon). Lymphoma patients are cared for in close co-operation between the light department and the lymphoma clinic in the dermatology department.
Unfortunately, since the end of 1999, whole-body PUVA therapy has no longer been covered by health insurance companies. This form of therapy is still routinely carried out on an inpatient and day-care basis, and this form of therapy is also to be made available to outpatients (a corresponding billing method is being worked on).

Bath PUVA therapy combines almost all the advantages of systematic PUVA therapy without its disadvantages. Application in pronounced psoriasis vulgaris with inverted diseases. However, outpatient treatment of hand and foot eczema is currently carried out using bath PUVA, in some cases with iontophoretic application of psoralens to the skin before irradiation.
In the case of hand and foot eczema associated with heavy sweating, a direct current treatment (iontophoresis) is first carried out before the bath PUVA therapy.
The PUVA therapies are carried out 4 times a week (Mon, Tue, Thu, Fri).

Photodynamic therapy allows actinic keratoses to be treated effectively in 3 - 10 sessions, even in the case of field carcinisation. For this purpose, a cream containing S-aminolevulinic acid is applied for 3 hours. S-aminolevulinic acid is converted to protoporphyrin. This is particularly well absorbed by genetically modified cells of actinic keratoses and multicentric superficial basal cell carcinoma. Subsequent irradiation with red light leads to the release of free radicals and selective apoptosis in the cells of these precancerous lesions or basal cell carcinoma. This therapy is extremely effective.

Extracorporeal photopheresis (ECP)

Extracorporeal photopheresis (ECP) is a phototherapeutic procedure for the treatment of patients with severe skin diseases such as graft-versus-host disease (GvHD) after bone marrow transplantation, organ transplant rejection (after heart and lung transplantation), T-cell lymphomas of the skin, scleroderma, severe atopic eczema and other autoimmune diseases.

It is a form of blood washing in which the white blood cells are first collected and, after special pre-treatment, irradiated with ultraviolet light (UV) and then returned to the patient.

This complex procedure is only available in specialised centres.

Extracorporeal photopheresis (ECP) technique

ECP is performed using a computer-controlled photopheresis system. The blood is separated by a centrifuge. Blood plasma enriched with white blood cells (leucocytes) (the so-called buffy coat) is collected and exposed to controlled UV-A irradiation in a circuit outside the body in the ECP device. The blood is then returned to the patient. The total duration of the treatment is approx. 3.5 hours.

Effect of extracorporeal photopheresis (ECP)

Light sensitisation is carried out in the leukocyte concentrate with an 8-methoxypsoral (8-MOP) solution. The activation of 8-MOP triggered by UV-A radiation causes a UV-A-mediated change in leucocyte function. The irradiated blood is presented to the non-irradiated immune system by returning it to the patient and, in addition to the direct cytostatic/cytotoxic (cell growth inhibiting) effects on the irradiated cells, can have a positive influence on the non-irradiated immune system.