Known and new facts on basal cell carcinoma.

Basal cell carcinoma (BCC) is the most common malignant tumor in light-skinned people and amounts to about 75 % of all cases of skin cancer. Increasing incidence rates have been reported for decades all over the world. The main risk factors include UV radiation, male sex, light skin type, advanced age, long-term immunosuppression, a positive individual or family history, and certain genodermatoses. BCC metastasizes only rarely, and its mortality is low, but it is associated with significant morbidity. Genetic mutations especially in the hedgehog pathway play an important role in BCC pathogenesis. Non-invasive procedures such as optical coherence tomography or confocal laser scan microscopy are increasingly utilized for diagnostics in addition to visual inspection and dermatoscopy, but only in exceptional cases can histological confirmation of the diagnosis be dispensed with. Various clinical and histological subtypes have been defined. Differentiating between BCC with high and low risk of recurrence has a significant influence on the choice of treatment. Most BCC can be treated effectively and safely with standard surgery, or in selected cases with topical treatment. Locally advanced and metastasized BCC must be treated with radiation or systemic therapy. Radiation is also an option for older patients with contraindications for surgery. The hedgehog inhibitors vismodegib and sonidegib are currently approved for systemic therapy of BCC in Europe. Approval for the PD1 inhibitor cemiplimab as second-line therapy is expected in the near future.

Laser-assisted epicutaneous immunization to target human skin dendritic cells.

Dendritic cells (DC) are promising targets for immunotherapy of cancer. Clinically, immunization against cancer antigens by means of the most potent antigen-presenting cells, that is DC, remains an important treatment option in combination with the modern immune checkpoint approaches. Instead of adoptively transferring in vitro monocyte-derived DC, they can also be loaded in situ by antibody-mediated targeting of antigen. Conventionally, these vaccines are delivered by classical intradermal injections. Here, we tested an alternative approach, namely laser-assisted epicutaneous immunization. With an infrared laser ("Precise Laser Epidermal System"/P.L.E.A.S.E.® Laser System), we created micropores in human skin and applied monoclonal antibodies (mAbs) against C-type lectins, for example DEC-205/CD205 and Langerin/CD207. Optimal parameters for formation of pores in epidermis and dermis were determined. We could induce pores of defined depths without enhanced apoptosis around them. Antibodies applied epicutaneously to the laser-porated skin could be detected both in Langerhans cells (LC) in situ in the epidermis and in migratory skin DC subsets from short term human skin explant culture, demonstrating uptake and transport of Langerin and DEC-205 mAbs. Efficacy of targeting was similar between the different laser treatments and pore depths. Thus, laser-assisted epicutaneous immunization may be a valuable alternative to intradermal injection, yet the loading efficacy of DC needs to be further improved.

Pseudoprogression with subsequent complete response and severe thrombocytopenia to checkpoint inhibitor immunotherapy in a patient with advanced mucosal melanoma of the sinonasal cavity.

In this case report, we describe a patient with an inoperable mucosal melanoma of the sinonasal cavity who achieved an ongoing complete response to combined immunotherapy with ipilimumab and nivolumab after initial pseudoprogression. Despite massive enlargement of the tumor 9 weeks after treatment initiation, we decided to continue with checkpoint inhibitor immunotherapy because of lacking potent therapeutic alternatives and the possibility of pseudoprogression. In the computed tomography scan 3 months later, the tumor was no longer detectable. To date, the patient is still in remission. However, she developed severe immune-related thrombocytopenia and neutropenia that are rarely encountered with checkpoint inhibitor immunotherapy. Thrombocytopenia did not respond to corticosteroids, but rapidly improved after the administration of single-dose intravenous immunoglobulin. This exceptional case highlights the effectiveness of combined immunotherapy with ipilimumab and nivolumab in mucosal melanoma, the phenomenon of pseudoprogression, as well as the rare event of immune-related hematological side effects.