SummaryBasal cell carcinoma (BCC) is the most common malignant tumor among fair‐skinned individuals, and its incidence had been steadily rising in the past decades. In order to maintain the highest quality of patient care possible, the German S2k guidelines were updated following a systematic literature search and with the participation of all professional societies and associations involved in the management of the disease. Part 2 addresses issues such as proper risk stratification, the various therapeutic approaches, and prevention as well as follow‐up of patients with basal cell carcinoma.

Basal cell carcinoma is the most common malignant tumor among fair-skinned individuals, and its incidence has been rising steadily in the past decades. In order to maintain the highest quality of patient care possible, the German S2k guidelines were updated following a systematic literature search and with the participation of all professional societies and associations involved in the management of the disease. Part 1 highlights new developments in genetics in particular as well as aspects regarding epidemiology, diagnosis, and histology.

Ultraviolet (UV) light represents one of the factors that might play a role in the initiation and promotion of malignant transformation of human melanocytes. To determine the short-term effects of UV irradiation on melanocytic nevi in vivo, we investigated one half of symmetric melanocytic nevi after a single UV exposure with double the patient's minimal erythema dose. This half was compared with the nonirradiated, shielded half of the same nevus. The different parts were examined histologically for differences and immunohistochemically for the presence of HMB-45 antigen and proliferating cell nuclear antigen. The features were assessed quantitatively by image analysis. One week after the single UV irradiation, we observed a significant increase of suprabasally located melanocytes and a markedly enhanced expression of HMB-45, whereas proliferative activity of the cells was unchanged. In nevi that were excised 2 or 3 weeks after irradiation, no significant differences were observed between the irradiated and the nonirradiated part. The results indicate that a single UV irradiation may induce transient melanocytic activation with morphologic and histologic changes. Although these data do not formally assess resemblance to melanoma, these changes may be similar to those of melanoma in situ.

Zusammenfassung Das Basalzellkarzinom (BZK) ist der häufigste maligne Tumor der hellhäutigen Bevölkerung mit jährlich steigender Inzidenz. Eine Aktualisierung der S2k‐Leitlinie unter Beteiligung aller mit dem Krankheitsbild vertrauten Fachgesellschaften sowie vorangegangener Literaturrecherche ist für die Qualität der Versorgung der betroffenen Patienten von essentieller Bedeutung. Im vorliegenden Teil 2 wird zunächst eine Risikostratifizierung aufgezeigt, bevor die verschiedenen Therapieoptionen diskutiert werden. Zudem werden Prävention und Nachsorge der Erkrankung behandelt.

In fibrotic skin of lipodermatosclerosis a substantial increase of the cross-link hydroxylysylpyridinoline is observed. Hydroxylysylpyridinoline is a typical cross-link of skeletal tissue and is thought to play a major part in the hardening of sclerotic tissue. We investigated whether the increase in hydroxylysylpyridinoline is due to overhydroxylation of lysyl residues in the collagen molecule, which may also be associated with an increase of glycosylated hydroxylysine residues. Furthermore, we determined whether the collagen fibrils in lipodermatosclerosis showed a decrease of the diameter in the tissue as well as in vitro after fibrillogenesis of pepsin-solubilized collagens. Isolated alpha-chains of pepsin solubilized collagen I showed an increase in lysyl hydroxylation (hyl/(hyl + lys)) as compared with normal control [alpha1(I): lipodermatosclerosis 0.18 +/- 0.01; control 0.12 +/- 0.01; alpha2(I): lipodermatosclerosis 0.36 +/- 0.02; control 0. 25 +/- 0.03, p < 0.001]. Furthermore, the content of enzymatic glycosylated hydroxlysine residues increased. This increase is associated with a decrease of fibril diameter of both tissue and fibrils formed in vitro of pepsin-solubilized collagens. In the same pool of collagens an increase in collagen III content was observed as compared with controls (lipodermatosclerosis 14.5% +/- 1.6, control 10.3% +/- 1.6, p < 0.001). Our results showed that the overhydroxylation of lysyl residues, which is required for the generation of hydroxylysylpyridinoline, is not only restricted to the telopeptides but also affects the helical part of the molecule. This process is further associated with an increase of glycosylated hydroxylysyl residues. These changes along with the increase in collagen III content seem to be responsible for the observed alteration in the architecture of collagen fibrils in sclerotic skin.