English online version on Wiley Online Library MinireviewZusammenfassung Der Morbus Dowling-Degos ist eine seltene, benigne Genodermatose. Charakteristisch sind lentiginöse Hyperpigmentierungen sowie rotbraune Papeln und Plaques. Häufig sind die Beugeseiten und Intertrigines betroffen, das klinische Bild kann jedoch variieren. Verantwortlich für die klinische Ausprägung sind Mutationen in unterschiedlichen Genen. Während Mutationen im Keratin 5 (KRT5)-Gen ein retikuläres Verteilungsmuster begünstigen, führen Mutationen im POGLUT1-Gen zu einem disseminierten, papulösen klinischen Bild. Die akantholytische Variante des Morbus Dowling-Degos wird historisch als Morbus Galli-Galli bezeichnet, unsere Falluntersuchung zeigt jedoch, dass die histopathologischen Veränderungen auch innerhalb eines Patienten variieren können. Bisher gibt es kein einheitliches Therapiekonzept. Keratolytische Maßnahmen stehen im Vordergrund, mit unterschiedlich gutem Ansprechen. Neue Therapieansätze mit Hilfe der Lasertechnologie scheinen eine vielversprechende Behandlungsoption zu sein.

Background The role of Borrelia in the development of skin lymphomas has been under discussion for decades. A similar association has been shown for Helicobacter pylori and gastric lymphomas (MALT type). Nevertheless, few molecular studies investigated Borrelia in skin lymphomas and the results are controversial. Methods We analysed 46 formalin‐fixed, paraffin‐embedded skin specimens of clincopathologically confirmed B‐cell lymphomas (15 marginal zone lymphomas; 20 follicular lymphomas; three diffuse large B‐cell lymphomas; eight secondary cutaneous infiltrates) taken from 36 patients from Northern Germany, an endemic area for Borrelia. Fifteen pseudolymphomatous lesions of cutaneous Borreliosis served as the control. Both groups were examined with a real‐time (rt) PCR and a semi‐nested PCR targeting the 5S‐23S intergenic spacer region (IGS). A multiplex PCR was used to investigate B‐cell clonality in all lymphomatous infiltrates (Biomed Primers). Results With both assays no Borrelia burgdorferi‐specific DNA was identified in any of the B‐cell lymphomas, while all 15 Borreliosis specimens gave a positive PCR result in the semi‐nested PCR protocol, 12 were also positive in the rt PCR (P < 0.01). All B‐cell lymphomas showed monoclonal IgH‐Rearrangement. Analysis of cutaneous B‐cell lymphomas from available studies including ours (n = 334) reveals an odds ratio <1. Conclusion While some previous studies suggested an association between B. burgdorferi and the development of cutaneous B‐cell lymphomas in endemic areas, we were unable to confirm this in our patients, despite a highly sensitive Borrelia PCR assay. Our results including meta‐analysis of previous studies question the need for antibiotic therapy in patients with cutaneous B‐cell lymphomas.

Summary Dowling‐Degos disease is a rare benign genodermatosis. It is characterized by lentiginous hyperpigmentation and reddish‐brown papules and plaques. The flexor sides and intertrigines are often affected, but the clinical appearance may vary. Mutations in different genes are responsible for the clinical manifestation. While mutations in the keratin 5 (KRT5) gene favor a reticular distribution pattern, mutations in the POGLUT1 gene lead to a disseminated, papular clinical picture. Acantholytic variants of Dowling‐Degos disease have historically been referred to as Galli‐Galli disease, but our case study shows that the histopathological changes can vary even within a single patient. To date, no standardized therapy concept exists. The main focus is on keratolytic measures, with varying response. New therapeutic approaches using laser technology appear to be a promising treatment option.