Pruritus – Pathophysiologie,Klinik und Therapie – Eine Übersicht

Pruritus is an unpleasant sensory perception of the skin associated with the desire to scratch. As a physiological nociception, pruritus leads to the removal of harmful agents such as parasites and plants from the skin surface. More often, pruritus occurs as a severe and therapy‐refractory symptom of various underlying dermatological and systemic diseases. Comparable to chronic pain, chronic pruritus worsens the general condition and may lead to physical and psychological exhaustion. Until the 1990s, pruritus had been regarded as an incomplete pain sensation. Only recently, itch was defined as a separate, pain‐independent sensation with its own mediators, spinal neurons and cortical areas. These observations led to the development of new therapeutic modalities. This paper gives an overview of itch pathophysiology, clinical types and therapies.     

Lichturtikaria – Urticaria solaris

Die Lichturtikaria ist eine seltene, IgE‐vermittelte und von Chromophoren abhängige Photodermatose. In manchen Fällen können diese Chromophore im Serum oder Plasma der Patienten als sogenannter „Serumfaktor“ nachgewiesen werden. Die genaue Pathogenese der Lichturtikaria ist jedoch bislang ungeklärt. Typisch ist die Quaddelbildung innerhalb weniger Minuten nach Lichtexposition, welche anamnestisch schon zur Verdachtsdiagnose führt. Die häufigsten Auslöser sind UV‐A oder sichtbares Licht. Diagnostisch von Bedeutung ist die Feststellung des Aktionsspektrums und der minimalen urtikariellen Dosis (MUD). Differenzialdiagnostisch müssen andere Lichtdermatosen (wie polymorphe Lichtdermatose) oder Porphyrien (insbesondere erythropoetische Protoporphyrie) ausgeschlossen werden. Außer dem stets notwendigen Lichtschutz werden moderne Antihistaminika sowie Lichtabhärtung (hardening) therapeutisch eingesetzt. Neuere Therapieverfahren wie die Plasmapherese oder der Anti‐IgE‐Antikörper Omalizumab bleiben schweren, therapieresistenten Formen vorbehalten.     

Ultraviolette Strahlung – Immunantwort

Ultraviolet (UV) radiation can exert a variety of biological effects, including induction of skin cancer, premature skin ageing and inhibition of the immune system. The immunosuppressive properties of UV radiation are of major biological and clinical relevance since suppression of the immune system by UV radiation also contributes to the induction of skin cancer. Hence, understanding of the mechanisms by which UV radiation compromises the immune system is of primary importance. UV radiation suppresses the immune system in multiple ways. It inhibits antigen presentation, stimulates the release of immunosuppressive cytokines and induces the generation of lymphocytes of the regulatory subtype. The major molecular target for UV‐induced immunosuppression is UV‐induced DNA damage. Further elucidation of the mechanisms underlying UV‐induced immunosuppression will not only lead to a better understanding of the physiologic and pathologic effects of UV radiation but also contribute to the development of new protective strategies.     

Mastocytosis – an update

Mastocytosis (MC) encompasses a range of disorders characterized by a clonal, pathological accumulation of mast cells having a somatic activating mutation of the tyrosine kinase receptor Kit (exon 17, codon 816; D816V) in more than 90 % of adult patients. The mutation is much less common in children. Skin and bone marrow are most often affected. Symptoms and clinical course are very heterogeneous due to a variable degree of local or systemic mediator release or organ dysfunction as a result of mast cell infiltrates. Pruritus, wheals, flushing and gastrointestinal symptoms are often reported. The majority of pediatric patients experience spontaneous remission of MC. Adults usually have chronic disease, rarely transforming into an aggressive or lethal type. Indolent systemic MC with involvement of skin and bone is the most common type. In MC the risk for anaphylactic reactions following an insect sting (and other causes of mast cell activation) is increased significantly. Diagnostic hallmarks are biopsies from skin and bone marrow using tryptase antibodies for staining as well as serum tryptase levels. At present a curative treatment for MC is not available. Systemic histamine H₁ receptor antagonists are widely used. Aggressive types of MC respond partially to IFN‐α or cladribine. A variety of receptor tyrosine kinase inhibitors is still under critical evaluation for systemic treatment of MC. After introduction of the WHO classification for MC and the development a German MC guideline, as well as the foundation of national and international competence networks for MC, a significantly improved quality of medical care for MC patients can be expected for the future.     

Multiple familial and pigmented basal cell carcinomas in early childhood – Bazex–Dupré–Christol syndrome

Background Bazex–Dupré–Christol syndrome (BDCS) is an X‐linked dominantly inherited disorder affecting hair follicle structures. Currently, hypotrichosis, follicular atrophoderma and basal cell carcinomas are considered frequent symptoms of the disorder whereas milia are supposed to reflect infrequent clinical signs. Usually, basal cell carcinomas in this disease manifest from the second decade of life onwards. Case report Here, we studied a novel multigeneration family of German origin with BDCS. Interestingly, two family members developed pigmented basal cell carcinomas in early childhood, at the age of 3 and 5 years, respectively. The differentiation from other pigmented lesions was accomplished by both dermoscopy and histopathology. A thorough survey of the current literature revealed that milia were present in almost all patients with BDCS reported, as is the case in our family. Conclusions We suggest that milia should also be considered frequent symptoms in BDCS. For the first time, to the best of our knowledge, we describe the occurrence of pigmented basal cell carcinomas in BDCS during the first decade of life. Our observation emphasizes the importance of screening for cutaneous malignancies in this disorder already at young age.