1 Department of Dermatology (Skin Cancer Centre Charité) and 2 Department of Nephrology, Charité, University Hospital Berlin, Germany
Correspondence and offprint requests to: Tobias Schmook, MD, Department of Dermatology (Skin Cancer Centre Charité), Charité University Hospital, Schumannstrasse 2021, D-10117 Berlin, Germany. Email: tobias.schmook{at}charite.de
Keywords: haemodialysis; kidney transplantation; methyl aminolaevulinate; nephrogenic fibrosing dermopathy; photodynamic therapy
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Introduction |
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Case |
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A skin biopsy of the left lower leg was consistent with the diagnosis of NFD. Histologically, thickened collagen bundles and surrounding clefts in the reticular dermis, plump bipolar spindle cells and longish fibroblasts were seen. The alcian blue staining was positive for mucin. Magnetic resonance tomography only showed a thicker dermis (3 mm), but excluded an involvement of deeper layers and soft parts. Other investigations, such as abdominal ultrasound and blood analysis (including electrolytes, blood count and also antibody profile), were inconspicuous.
As therapy we administered photodynamic therapy (PDT) with the lipophilic agent methyl aminolaevulinate (MAL) on the skin of the left lower leg. Following 3 h under occlusion, illumination was performed with red light emitted from high-brightness light-emitting diodes (LEDs) at a distance of 810 cm. During the treatment the patient mentioned slight stinging and pain in the illuminated area. No other side effects were observed. After 2 weeks we repeated the MALPDT on the same lesion and after a further 4 weeks, normal soft skin with distinct hair growth was observed clearly (Figure 1b). The right lower leg was also successfully treated with MALPDT. The immunosuppressive therapy remained unchanged. The patient was content and free of pain and has shown no relapse for 13 months after the first PDT. Thus, MALPDT seems to be effective and well tolerated in NFD.
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Discussion |
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Another rarer collagenous disease is NFD, which shows a thickened or oedematous skin with induration on papules and plaques, often located on extremities and on the trunk. NFD should be distinguished from other fibrotic disorders, such as localized scleroderma, scleromyxoedema, toxic-oil syndrome, scleredema adultorum, systemic sclerosis, calciphylaxis and eosinophilic fasciitis. All these differential diagnoses have thickened and indurated skin. The correct diagnosis can be established with clinical findings, histological examination and an investigation of internal organs. Until now, no definitive therapy for NFD has been available. Experimental therapies contain chemotoxic and immunosuppressive agents, such as prednisone, thalidomide, mycophenolate mofetil, calcineurin inhibitors and plasmapheresis [7] [www.pathmax.com/dermweb/]. These treatments are costly, cause side effects for the patients and a positive outcome is not guaranteed.
PDT is said to be effective in localized scleroderma, which has, like NFD, an increase and a bundling of collagen in the skin [8]. Therefore, PDT was applied with the haem-prodrug aminolaevulinic acid (ALA). The PDT induces matrix metalloproteinases in fibroblasts and a reduction of collagen synthesis in the dermis [9]. The described elastic effect of PDT in other collagenous diseases was the rationale of our application of PDT in NFD. The mode of action of PDT in NFD is unclear; a supposable functionality beside the induction of matrix metalloproteinases may be the production of oxygen species that make the tissue more elastic due to destruction of collagen [9]. The patient benefited definitely from the treatment that shows very good efficacy and safety.
Usually, PDT is a treatment for some types of cancer. Therefore, the photosensitizing agent is topically applied (cream, instillation) or injected into the bloodstream. The agent penetrates and remains in cells with an increased metabolism, mainly cancer cells, in a higher concentration than in normal cells. Under light exposition, the photosensitizing agent absorbs the light and produces an active form of oxygen that destroys the treated cancer cells (photodynamic effect). PDT causes minimal damage to healthy tissue. For the treatment of internal tumours, a laser light can be directed through a fibre-optic cable, i.e. for lung, oesophageal or bladder cancer [10]. On the skin, topical agents such as ALA or MAL may be used and are indicated for use in PDT. In vivo, these agents stimulate the production of porphyrins, which act as powerful photosensitizers. Porphyrins produced by the action of ALA or MAL can be activated using red light, which is also capable of deeply penetrating the skin (5 mm). For PDT light sources, convenient non-laser sources, such as non-coherent filtered lamps, and, more recently, sources containing arrays of LEDs, can be used. The LED lamp in the presented case had an emission spectrum of 634±3 nm and a light dose of 37 J/cm(2).
This survey should be the basis for further investigations in the efficacy and mode of action of PDT in NFD.
Conflict of interest statement. None declared.
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