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Background: Hidradenitis suppurativa (HS) is a chronic inflammatory disease that is highly correlated with obesity. Haptoglobin serum levels have recently been recognized as an important biomarker linking obesity with chronic inflammation. Objective: To compare haptoglobin with previously proposed serum biomarkers for the determination of disease severity in HS patients. For this purpose, disease severity of HS patients was determined by a panel of clinical scores as well as several risk factors, such as weight and smoking habits. Methods: A prospective, diagnostic accuracy study was performed at the International Centre for Hidradenitis suppurativa/Acne inversa Bochum (ICH). The study included a total of 263 patients, including 131 who had a confirmed diagnosis of HS in Hurley I (n = 16), II (n = 56) and III (n = 59) HS, and 132 healthy controls. The main outcome was to identify serological inflammatory markers for HS disease severity [severe (III) vs. moderate/mild (II/I)] as assessed by Hurley classification. Results: The serum levels of acute phase proteins haptoglobin and CRP, as well as the number of neutrophils in peripheral blood, number of monocytes, the systemic immune‐inflammation index and the pan‐immune‐inflammatory value correlated with disease severity according to established clinical scores (mHSS, SAHS, Hurley, DLQI). HS patients had significantly higher haptologlobin levels compared to healthy controls. Logistic regression analysis revealed haptoglobin as the only independent marker predicting severe HS. Conclusion: In this prospective study, we discovered that the serum levels of the acute phase protein haptoglobin levels serve as an independent marker of disease severity in HS. While this presents the first study in the context of HS. Thus, the present data not only yield a highly promising serum marker to be further validated. [ABSTRACT FROM AUTHOR]

There is growing evidence that not only the novel coronavirus disease (COVID‐19) but also the COVID‐19 vaccines can cause a variety of skin reactions. In this review article, we provide a brief overview on cutaneous findings that have been observed since the emerging mass COVID‐19 vaccination campaigns all over the world. Unspecific injection‐site reactions very early occurring after the vaccination are most frequent. Type I hypersensitivity reactions (e.g. urticaria, angio‐oedema and anaphylaxis) likely due to allergy to ingredients may rarely occur but can be severe. Type IV hypersensitivity reactions may be observed, including delayed large local skin lesions ("COVID arm"), inflammatory reactions in dermal filler or previous radiation sites or even old BCG scars, and more commonly morbilliform and erythema multiforme‐like rashes. Autoimmune‐mediated skin findings after COVID‐19 vaccination include leucocytoclastic vasculitis, lupus erythematosus and immune thrombocytopenia. Functional angiopathies (chilblain‐like lesions, erythromelalgia) may also be observed. Pityriasis rosea‐like rashes and reactivation of herpes zoster have also been reported after COVID‐19 vaccination. In conclusion, there are numerous cutaneous reaction patterns that may occur following COVID‐19 vaccination, whereby many of these skin findings are of immunological/autoimmunological nature. Importantly, molecular mimicry exists between SARS‐CoV‐2 (e.g. the spike‐protein sequences used to design the vaccines) and human components and may thus explain some COVID‐19 pathologies as well as adverse skin reactions to COVID‐19 vaccinations. Linked Commentary: P. Gisondi et al. J Eur Acad Dermatol Venereol 2022; 36: 165–166. https://doi.org/10.1111/jdv.17854. [ABSTRACT FROM AUTHOR]

Competing Interests: Conflicts of interest Dr Abu Rached received funding, travel support, and/or personal honoraria for lectures from Novartis Pharma and Johnson & Johnson that were independent of the work submitted. Dr Hessam has received honoraria for participation in advisory boards, in clinical trials, and/or as a speaker from AbbVie Inc, AbbVie Deutschland GmbH & Co KG, Bristol-Myers Squibb GmbH & Co KGaA, Novartis Pharma GmbH, Bristol-Myers Squibb GmbH & Co. KGaA, Almirall Hermal GmbH. Prof Bechara has received honoraria for participation in advisory boards, in clinical trials, and/or as a speaker from AbbVie Inc, AbbVie Deutschland GmbH & Co KG, Boehringer Ingelheim Pharma GmbH & Co KG, Novartis Pharma GmbH, UCB Pharma, Incyte Corporation, and JanssenCilag GmbH, MoonLake. Prof Stockfleth has received lecture fees from Almirall, Leo, Pierre Favre and Philips. Dr Ocker has received honoraria as a speaker and/or travel support from Novartis Pharma GmbH, Incyte Biosciences Corporation, and Janssen. Prof Gambichler has received speakers and/or advisory board honoraria from BMS, Sanofi-Genzyme, MSD, Novartis Pharma, Roche, Abbvie, Almirall, Janssen, Lilly, Pfizer, Pierre Fabre, and Merck-Serono outside the submitted work. Drs Herbst and Skrygan have no conflicts of interest to declare.

Background: Neoadjuvant and adjuvant therapies are currently getting increasingly important in cutaneous melanoma (CM) management. However, there is still a lack of prognostic tools to identify which patients have a poor prognosis. There is increasing evidence that the liver score may be a potential prognostic parameter in different tumour types. The aim was to investigate whether established liver scores can establish the prognosis of CM. Methods: According to established methods, the APRI, the MELD score, the MELD-Na score and the De Ritis ratio were calculated from the laboratory values at the time of the initial diagnosis. Survival was compared with the Kaplan-Meier curve and tested with log-rank tests. Risk factors associated with cutaneous melanoma-specific survival (CMSS) and progression-free survival (PFS) were assessed by using the Cox proportional hazards regression model. To determine the diagnostic accuracy, we performed a time-dependent ROC analysis. Results: A total of 423 patients were included, including 141 patients in AJCC stage (2017) I (33.3%), 82 in stage II (19.4%), 128 in stage III (30.3%) and 72 in stage IV (17%). Median time until melanoma-specific death was 99 months (IQR: 37-126). In addition, 37.6% of patients relapsed with a median time to relapse of 88 months (IQR: 17.5-126). In all stages, tumour thickness and ulceration were independent markers for predicting CMSS and PFS ( p < 0.05). The multivariable analysis with all stages showed no significant association with CM outcome for liver scores ( p > 0.05). The subgroup analysis revealed that the APRI (≥0.2241) was associated with CMSS and PFS in melanoma stages I and II, independently of tumour thickness, age and ulceration (HR 2.57, 95% CI 1.14-5.75; HR 2.94, 95% CI 1.42-6.09, respectively). Conclusions: The 20-year prognosis of AJCC stage I and II CM was dependent on tumour thickness and the APRI. High tumour thickness and an APRI ≥ 0.2241 at the initial diagnosis were associated with a worse prognosis. Future studies should investigate the independent prognostic value of the APRI in low-stage CM. Furthermore, the APRI score could be a potential biomarker for nomograms.

Purpose: Hidradenitis suppurativa (HS) is a chronic inflammatory disease associated with an increased risk of malignancy. The aim of this systematic review was to investigate the prevalence of different malignancies in HS., Methods: This review meets the PRISMA criteria. A data-driven approach was used to conduct the research, which involved a detailed keyword search. The study considered meta-analyses, experimental studies, case-control studies, cross-sectional studies, cohort studies, and recently published cases, published in English or German. Excluded were reviews, summaries, and letters to the editor, as well as studies, which are not based on the human population., Results: Out of the initial 443 publications found, 25 met the inclusion criteria for this systematic review. Patients with HS have a significantly increased risk of cancer, up to 50%. Additionally, the risk of oropharyngeal, central nervous system, colorectal, prostate, vulvar and non-melanocytic skin cancers increase with the severity of HS. The likelihood of comorbid lymphoma in patients with HS is significantly higher compared to healthy controls. In severe cases of HS, malignant degeneration of lesions in the groin, perianal, perineal, and gluteal region can occur in up to 4.6% of cases. This leads to the development of cSCC, which often have a complicated course, are more refractory to treatment and associated with a poorer outcome. The pathogenic mechanisms responsible for the malignant transformation of HS are currently unknown., Conclusions: Patients with HS have a higher risk of cancer compared to the general population. Untreated, long-standing HS lesions can lead to complicated malignant degeneration resulting in cutaneous squamous cell carcinoma. The mechanisms underlying this malignant degeneration are not fully understood. HS patients also have an increased risk of developing other cancers, including prostate, oral, pharyngeal and colorectal cancers of the central nervous system and lymphomas.

Introduction: Merkel cell carcinoma (MCC) is an aggressive skin cancer with a poor prognosis, which only improved with the introduction of immunotherapies. An MCC prediction model with high diagnostic accuracy is lacking. The aim was to develop an MCC prognostic score (MCC-PS) based on combinations of previously proposed risk factors., Methods: A multicentric, retrospective study was conducted to develop MCC-PS, which included age, neuron-specific enolase (NSE), C-reactive protein (CRP), creatinine, bilirubin, and international normalized ratio (INR). Creatinine, bilirubin, and INR were used to calculate the model of end-stage liver disease (MELD) score. A total of 98 patients were included in the study, including 36.7% with stage I according to American Joint Committee on Cancer 2018 ( n = 36), 30.6% with stage II ( n = 30), 25.5% with stage III ( n = 25), and 7.1% with stage IV ( n = 7). Survival data of MCC patients were correlated with selected laboratory parameters and risk factors. Primary endpoint was MCC-specific survival (MSS) and the secondary endpoint was progression-free survival. Several statistical methods were used to develop the prognostic score, including correlation analysis, Kaplan-Meier curves, Cox regression, and time-dependent receiver operating characteristic analysis., Results: The MCC-PS is based on the sum of the following baseline variables: elevated CRP (≥5.5 mg/l), elevated NSE (≥22.8 µg/l), MELD score ≥ 11, and age ≥ 75 years. An MELD score ≥ 11 was scored as 4 points, elevated NSE level as 3 points, elevated CRP level as 2 points, and age ≥ 75 years as 1 point. A high-risk group according to the MCC-PS was characterized by a score of 4 or more points. The high-risk group was associated with a worse prognosis than the low-risk group (1-year MSS 62%, 2-year 43.1%, 5-year 17.6% as compared to 1-year MSS 79.5%, 3-year 75%, 5-year 72%). Notably, the developed MCC-PS predicts MCC outcome measures with high accuracy (3-year MSS: area under the curve (AUC) 0.934, sensitivity 87.5% and specificity 82.2%; 5-year MSS: AUC 0.93, sensitivity 89% and specificity 82%)., Conclusion: MCC-PS is the first prognostic score predicting MCC outcome with a high accuracy based on five easily available laboratory parameters and patient's age. An MCC-PS of 4 or more indicates a high-risk patient associated with a poor prognosis., Competing Interests: JB is receiving speaker’s bureau honoraria from Amgen, Pfizer, Merck-Serono, and Sanofi and is a paid consultant/advisory board member for eTheRNA, Merck-Serono, Pfizer, 4SC, and Sanofi. His group receives research grants from BMS, Merck-Serono, and Alcedis. TG has received speakers and/or advisory board honoraria from BMS, Sanofi-Genzyme, MSD, Novartis Pharma, Roche, Abbvie, Almirall, Janssen, Lilly, Pfizer, Pierre Fabre, and Merck-Serono outside the submitted work. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Abu Rached, Becker, Lonsdorf, Keller, Zeglis and Gambichler.)

Background: Immune complex vasculitides may be subdivided into adult IgA small vessel vasculitis (aIgA-SVV; i.e. adult Henoch-Schönlein purpura) and non-IgA-SVV (hypersensitivity vasculitis, etc.)., Objectives: To evaluate the clinical and laboratory parameters of inpatients fulfilling the diagnostic criteria for aIgA-SVV and non-IgA-SVV., Methods: Twenty-nine adults aged ≥ 20 years with aIgA-SVV [according to the European League Against Rheumatism/Paediatric Rheumatology International Trials Organisation/Paediatric Rheumatology European Society (EULAR/PRINTO/PRES) criteria] and 53 adults with non-IgA-SVV (according to the 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides) were compared with respect to a variety of clinical and laboratory parameters by uni- and multivariable analyses., Results: Compared with patients with aIgA-SVV, the platelet-to-lymphocyte ratio was significantly higher in patients with non-IgA-SVV. Serum C3 levels and mean corpuscular haemoglobin concentration in patients with non-IgA-SVV were significantly lower compared with patients with aIgA-SVV. Proteinuria and haematuria were significantly more common in patients with aIgA SVV, and were significantly correlated with systemic immune-inflammation biomarkers only in patients with aIgA-SVV. In patients with aIgA-SVV, higher lactate dehydrogenase and C-reactive protein were strong independent predictors for the presence of proteinuria and proteinuria. In patients with non-IgA-SVV, female sex was a protective factor for proteinuria, while skin lesions on the upper extremities proved to be a significant independent predictor of haematuria., Conclusions: We detected several clinical and laboratory differences between patients with aIgA-SVV and non-IgA-SVV. Distinct predictors for renal involvement were not observed in either group, indicating that aIgA-SVV and non-IgA-SVV are similar conditions but do not appear to represent the same entity., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Hidradenitis suppurativa (HS) is a debilitating, chronic inflammatory disease associated with multiple triggers. As the world struggles with the global COVID-19 pandemic, it is important to review the trigger factors for chronically ill HS patients during the COVID-19 pandemic. This work investigates the self-described trigger factors of HS patients that emerged during the COVID-19 outbreak. Methods : We anonymously surveyed 110 HS patients during the SARS-CoV-2 pandemic using a 25-question questionnaire that included trigger factors for deterioration. Demographic, personal, and HS-specific information was also collected to identify potential trigger factors for HS exacerbation. All HS patients were asked if their HS had worsened compared to the time before the pandemic. Results: Compared to before the pandemic, 20% of HS patients ( n = 22) reported a worsening of HS. Patients with an HS exacerbation were significantly more likely to avoid contact with a doctor than those without an exacerbation (45.5% vs. 18.2%; p = 0.007). HS involvement, severity, exercise activity, and BMI had no association with worsening HS ( p > 0.05). Interestingly, dietary changes and increased consumption of sweets and treats were associated with worsening HS ( p = 0.011 and p = 0.013). Specifically, eating more sweets and treats was associated with a 6-fold increased risk of worsening HS. The results suggest that diet has an important influence on HS relapses. Further investigation is needed to determine whether diet is a triggering factor independent of the SARS-CoV-2 pandemic. In addition, gluteal HS involvement was associated with a more than 4.3-fold risk of HS exacerbation. Conclusions: In the management of HS patients, it is important to consider that gluteal involvement and the consumption of sweets are more often associated with deterioration.

Merkel cell carcinoma is a rare, aggressive skin cancer that mainly occurs in elderly and immunocompromised patients. Due to the success of immune checkpoint inhibition in MCC, the importance of immunotherapy and vaccines in MCC has increased in recent years. In this article, we aim to present the current progress and perspectives in the development of vaccines for this disease. Here, we summarize and discuss the current literature and ongoing clinical trials investigating vaccines against MCC. We identified 10 articles through a PubMed search investigating a vaccine against MCC. From the international clinical trial database Clinical.Trials.gov, we identified nine studies on vaccines for the management of MCC, of which seven are actively recruiting. Most of the identified studies investigating a vaccine against MCC are preclinical or phase 1/2 trials. The vaccine principles mainly included DNA- and (synthetic) peptide-based vaccines, but RNA-based vaccines, oncolytic viruses, and the combination of vaccines and immunotherapy are also under investigation for the treatment of MCC. Although the management of MCC is changing, when compared to times before the approval of immune checkpoint inhibitors, it will still take some time before the first MCC vaccine is ready for approval.

Hidradenitis suppurativa (HS) is a chronic skin disease that can have an association with endocrine disorders. There is conflicting information in the literature regarding the role of the thyroid gland in HS. This study aimed to close this knowledge gap and investigate how thyroid disease is involved in patients with HS. We carried out a case-control study with a total of 160 patients, of whom 108 were patients with HS and 52 were controls matched for age and sex. Parametric and non-parametric methods were used to analyze the results. We calculated structural parameters of thyroid homeostasis to detect subclinical thyroid disease, non-thyroid disease syndrome and other forms. The severity of HS was not associated with thyroid hormone levels and antibodies ( p > 0.05). HS patients with or without hypothyroidism had decreased FT4 levels and a decreased thyroid secretory capacity (SPINA-GT). Titers of TSH receptor autoantibodies (TRAb) were significantly higher in smoking HS patients compared to non-smokers (median: 1.18 vs. 1.08; p = 0.042). The rate of subclinical hypothyroidism was significantly higher in HS patients; thus, subclinical hypothyroidism is an important comorbidity of HS ( p < 0.05). Further studies are needed to investigate whether the chronic inflammation of HS is a cause of increased rates of (subclinical) hypothyroidism.

Background: Even in the novel immunotherapy era, Merkel cell carcinoma (MCC) remains challenging in its treatment. Apart from Merkel cell polyomavirus (MCPyV) associated MCC, this cancer is linked in about 20% of cases to ultraviolet-induced mutational burden frequently causing aberrations in Notch and PI3K/AKT/mTOR signalling pathways. The recently developed agent GP-2250 is capable to inhibit growth of cells of different cancers, including pancreatic neuroendocrine tumors. The objective of the present study was to investigate the effects of GP-2250 on MCPyV-negative MCC cells., Methods: Methods We employed three cell lines (MCC13, MCC14.2, MCC26) which were exposed to different GP-2250doses. GP-2250's effects on cell viability, proliferation, and migration were evaluated by means of MTT, BrdU, and scratch assays, respectively. Flow cytometry was performed for the evaluation of apoptosis and necrosis. Western blotting was implemented for the determination of AKT, mTOR, STAT3, and Notch1 protein expression., Results: Cell viability, proliferation, and migration decreased with increasing GP-2250 doses. Flow cytometry revealed a dose response to GP-2250 in all three MCC cell lines. While the viable fraction decreased, the share of necrotic and in a smaller amount the apoptotic cells increased. Regarding Notch1, AKT, mTOR, and STAT3 expression a comparatively time- and dose-dependent decrease of protein expression in the MCC13 and MCC26 cell lines was observed. By contrast, Notch1, AKT, mTOR, and STAT3 expression in MCC14.2 was scarcely altered or even increased by the three dosages of GP-2250 applied., Conclusions: The present study indicates GP-2250 having anti-neoplastic effects in MCPyV-negative tumor cells in regard to viability, proliferation, and migration. Moreover, the substance is capable of downregulating protein expression of aberrant tumorigenic pathways in MCPyV-negative MCC cells., (© 2023. The Author(s).)

Chronic wounds (CWs) pose a significant health challenge in clinical practice. Standard wound therapy (SWT) is currently considered the gold standard. However, recent evidence suggests that cold plasma therapy (CPT) holds promise for improving CWs. In light of this, the POWER study was conducted as a multicenter, randomized clinical trial to investigate the effect of large-area plasma application compared with SWT in patients with chronic, non-healing arterial or venous wounds on the lower leg. To analyze the interim results, we employed a comprehensive range of statistical tests, including both parametric and non-parametric methods, as well as GLS model regression and an ordinal mixed model. Our findings clearly demonstrate that CPT therapy significantly accelerates wound closure compared with SWT. In fact, complete wound closure was exclusively observed in the CPT group during the intervention period. Additionally, the CPT group required significantly less antibiotic therapy (4%) compared with the SWT group (23%). Furthermore, CPT led to a significant reduction in wound pain and improved quality of life compared with SWT. In conclusion, the study highlights that the combination of CPT and SWT surpasses monotherapy with SWT alone.

Merkel cell carcinoma (MCC) is a highly malignant skin tumor that occurs mainly in elderly and/or immunosuppressed patients. MCC prognosis has been significantly improved by the introduction of immune checkpoint inhibitor treatment. Recently, blood-based biomarkers have been investigated that can potentially predict the outcome of MCC patients. In this context, parameters of liver scores have not yet been investigated. We retrospectively recruited 47 MCC patients with available relevant laboratory data at primary diagnosis. At this time, we investigated blood-based scores as follows: model for end-stage liver disease (MELD), aspartate aminotransferase/platelet count ratio index (APRI), and the alanine transaminase/aspartate aminotransferase ratio (De Ritis ratio). MCC relapse was negatively correlated with the De Ritis score (r = -0.3, p = 0.024) and positively correlated with the MELD score (r = 0.3, p = 0.035). Moreover, MCC-specific death positively correlated with CCI score (r = 0.4, p = 0.01) and MELD score (r = 0.4, p = 0.003). In multivariable analysis, the MELD score remained in the regression model as significant independent predictor for MCC relapse (hazard ratio: 1.16 (95% CI 1.04 to 1.29; p = 0.008) and MCC-specific death (hazard ratio: 1.2 (95% CI 1.04 to 1.3; p = 0.009). We observed for the first time that the MELD score appears to independently predict both MCC relapse and MCC-specific death. These results should be further investigated in larger prospective studies.

Hidradenitis suppurativa (HS) is a chronic skin disease that is often associated with metabolic disorders. Diabetes mellitus (DM) is a frequent comorbidity in HS. There is currently no established screening for DM in HS patients. The aim of our study was to identify high-risk groups of HS patients that develop DM and to assess the frequency of different types of DM present in HS patients. To do so, we conducted a monocentric study in 99 patients with HS. All patients underwent detailed clinical and laboratory assessments, including the determination of glycated hemoglobin. Among the 20.2% of patients that presented with DM, type 2 was by far the most prevalent (19 out of 20 patients). Moreover, male gender, age, BMI, Hurley stage, modified Hidradenitis Suppurativa Score (mHSS), DLQI and hypertension all correlated with the glycated hemoglobin levels in the HS patients. In the multivariable analysis, Hurley stage III, older age, and higher BMI were significantly associated with DM. Specifically, patients at Hurley stage III were at a 5.3-fold increased risk of having DM type II compared to patients at earlier Hurley stages. Since many of the HS patients had not been diagnosed, our study reveals shortcomings in the screening for DM and suggest that this should be routinely performed in HS patients at high risk to avoid secondary complications.

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease presenting with recurrent inflammatory lesions in intertriginous body regions. HS has a pronounced impact on patients' quality of life and is associated with a variety of comorbidities. Treatment of HS is often complex, requiring an individual approach with medical and surgical treatments available. However, especially in moderate-to-severe HS, there is an urgent need for new treatment approaches. In recent years, increased research has led to the identification of new potential therapeutic targets. This review aims to give a comprehensive and practical overview of current treatment options for HS. Furthermore, the clinically most advanced novel treatment approaches will be discussed.

Hidradenitis suppurativa (HS) is a chronic inflammatory disease manifesting in inverse body regions. In a systematic review, the role of hormones in HS will be presented to better understand the pathomechanisms of HS. The review is based on the PRISMA criteria. Systematic research was carried out using keywords. Subsequently, the data were analyzed based on the clinical response and other relevant information. The main focus of our systematic review was on HS manifestation, exacerbation, sex hormones, antiandrogen therapy, thyroid function, polycystic ovary syndrome, insulin resistance, and adipokines. In HS, there appears to be a dysregulated adipokine release that is shifted towards pro-inflammatory adipokines. Insulin resistance is significantly more common in HS than in healthy patients regardless of BMI, age, and gender. Insulin resistance in HS patients leads to further cardiovascular disease. The mechanism of insulin resistance and role of adipokines should be investigated in future studies to better provide the pathomechanisms of HS. The role of androgens seems to be important in a certain subgroup of female patients. Anti-androgenic therapy can be useful and helpful in some patients. However, further studies are needed to better understand the hormonal relationship in HS.

Prognostic biomarkers derived from complete blood count (CBC) have received marked interest as an indirect measure of the inflammatory pressure in cancers such as metastatic melanoma. Here, we evaluated the novel pan-immune-inflammation value (PIV) and the frequently assessed neutrophil/lymphocyte ratio (NLR) in a large cohort of patients with cutaneous melanoma (CM) without distant metastases (stages I to III). PIV and NLR were calculated at CM diagnosis. Healthy controls were also included. We used the Kaplan-Meier method to estimate crude survival probabilities and used Cox proportional hazards regression for multiple adjustment of hazard ratios. We observed that higher PIV (HR: 1.72, 95% CI 1.14 to 2.58 and HR: 1.696, 95% CI 1.029 to 2.795, respectively) and NLR (HR: 1.70, 95% CI 1.10 to 2.62) values were associated with CM relapse and CM-specific death in the crude analysis. However, when adjusting for potential confounders, in particular age and tumor thickness, the total effect of PIV and NLR on CM-relapse-free (HR: 1.28, 95% CI 0.83 to 1.98 and HR: 1.26, 95% CI 0.80 to 1.98, respectively) and CM-specific survival (HR: 1.36, 95% CI 0.80 to 2.30 and HR: 1.37, 95% CI 0.80 to 2.33, respectively) was substantially reduced. However, both PIV and NLR were positively correlated with age and tumor thickness, which are important independent predictors for CM relapse and CM-specific death. In conclusion, in stage I to III CM patients PIV as well as NLR appear to be confounded by age and tumor thickness and probably have no potential to further improve the prediction of survival of stage I to III CM patients beyond standard prognostic factors.

There exist relatively sparse and conflicting data on high-level microsatellite instability (MSI-H) and deficient mismatch repair (dMMR) in cutaneous malignancies. We aimed to determine the expression profiles of MMR proteins (MSH2, MSH6, MLH1, and PMS2) in different progression stages of cutaneous squamous cell carcinoma (cSCC, 102 patients in total) by immunohistochemistry, and search for MSI-H in patients with low-level MMR or dMMR using multiplex-PCR. Low-level MMR protein expression was observed in five patients: One patient with primary cSCC < 2 mm thickness and low-level MLH1, three patients with primary cSCC > 6 mm (including one with low-level MSH2, as well as MSH6 expression, and two with low-level PMS2), and one patient with a cSCC metastasis showing low-level MSH2 as well as MSH6. Intergroup protein expression analysis revealed that MLH1 and MSH2 expression in actinic keratosis was significantly decreased when compared to Bowen's disease, cSCC < 2 mm, cSCC > 6 mm, and cSCC metastasis. In cases with low-level MMR, we performed MSI-H tests revealing three cases with MSI-H and one with low-level MSI-L. We found low-level MMR expression in a small subset of patients with invasive or metastatic cSCC. Hence, loss of MMR expression may be associated with tumour progression in a small subgroup of patients with non-melanoma skin cancer.

We aimed to assess for the first time the mismatch repair (MMR) protein expression in Merkel cell carcinoma (MCC). Immunohistochemistry was performed for MLH1, MSH2, MSH6, and PMS2 on patients' tumor tissue ( n = 56), including neighbored healthy control tissue. In cases with low-level MMR expression (<10th percentile), we performed multiplex PCR in combination with high-resolution capillary electrophoresis in order to confirm microsatellite instability (MSI). Microscopic evaluation revealed a high median expression for all MMR proteins studied (91.6-96.3%). However, six patients (56/10.7%) had low-level MLH1 expression, six (55/10.9%) had low-level MSH2 expression, five (56/8.9%) had low-level MSH6 expression, and six (54/11.1%) had low-level PMS2 expression. Together, we observed nine (56/16.1%) patients who had low-level MMR expression of at least one protein. Of the patients with low-level MMR expression, MSI evaluation was possible in five cases, revealing one case with high-level MSI. In all MMR proteins assessed, low-level expression was significantly ( p = 0.0004 to p < 0.0001) associated with a negative Merkel cell polyomavirus (MCPyV) status. However, the expression profiles of the MMR proteins did not correlate with clinical outcome measures such as disease relapse or death ( p > 0.05). MCC appears to be a malignancy characterized by low-level MMR rather than completely deficient MMR in a subset of cases, predominantly affecting MCPyV-negative tumors. Future studies will establish whether this subset of MCC patients respond better to immune checkpoint inhibitor therapy.