[Erythema nodosum]. / Erythema nodosum.

Erythema nodosum (EN) is the most frequently occurring form of acute panniculitis. It is characterized by painful red to livid raised nodules or bumps that typically occur symmetrically in the shin area. The cause of EN is often a reaction of the immune system to various triggers including infections, inflammatory diseases or medications. In approximately half of the cases no trigger can be identified. After treatment of the underlying pathology EN is typically self-limiting.

COL10A1 expression distinguishes a subset of cancer-associated fibroblasts present in the stroma of high-risk basal cell carcinoma.

BACKGROUND: Basal cell carcinoma (BCC) is the most frequently diagnosed skin cancer and the most common malignancy in humans. Different morphological subtypes of BCC are associated with low- or high-risk of recurrence and aggressiveness, but the underlying biology of how the individual subtypes arise remains largely unknown. Because the majority of BCCs appear to arise from mutations in the same pathway, we hypothesized that BCC development, growth and invasive potential is also influenced by the tumor microenvironment and in particular by cancer-associated fibroblasts (CAFs) and their secreted factors. OBJECTIVE: We aimed to characterize the stroma of the different BCC subtypes with a focus on CAF populations. METHODS: To investigate the stromal features of the different BCC subtypes, we applied laser-capture microdissection (LCM) followed by RNA sequencing. A cohort of 15 BCC samples from 5 different "pure" subtypes (superficial, nodular, micronodular, sclerosing and basosquamous; n=3 each) were selected and included in the analysis. Healthy skin was used as a control (n=6). We confirmed the results by immunohistochemistry. We validated our findings in two independent, public single-cell RNA sequencing (scRNAseq) datasets and by RNAscope. RESULTS: The stroma of the different BCC subtypes have distinct gene expression signatures. Nodular and micronodular seem to have the most similar signatures, while superficial and sclerosing the most different. By comparing low- and high-risk BCC subtypes, we observed that Collagen 10A1 (COL10A1) is overexpressed in the stroma of sclerosing/infiltrative and basosquamous but not micronodular high-risk subtypes. Those findings were confirmed by immunohistochemistry in a cohort of 89 different BCC and 13 healthy skin samples. Moreover, scRNAseq analysis of BCCs of two independent datasets showed that the COL10A1-expressing population of cells is associated with the stroma adjacent to invasive BCC and shows extracellular matrix remodeling features. CONCLUSION: We identified COL10A1 as a marker of high-risk BCC, in particular of the sclerosing/infiltrative and basosquamous subtypes. We demonstrated at the single cell level that COL10A1 is expressed by a specific CAF population associated with the stroma of invasive BCC. This opens up new tailored treatment options as well as a new prognostic biomarker for BCC progression.

Checkpoint inhibitor-induced lichen planus differs from spontaneous lichen planus on the clinical, histological, and gene expression level.

Background: Although highly efficacious, immune checkpoint inhibitors induce a multitude of immune-related adverse events including lichenoid skin reactions (irLP) that are often therapy-resistant. Objectives: To compare the clinical, histological, and transcriptional features of irLP with spontaneous lichen planus (LP). Methods: Clinical and histological presentations of irLP and LP, as well as the gene expression profiles of irLP and LP lesional and healthy skin were assessed. Results: irLP differed considerably from LP with regard to the distribution pattern of skin lesions with irLP appearing mostly in an exanthematous form, whereas lesions were more localized in the LP group. Histologically, dermal lymphocyte infiltration was significantly lower in irLP compared with LP, whereas lymphocyte exocytosis and apoptotic keratinocytes were significantly higher in irLP. Gene expression analysis revealed irLP to have a more inflammatory profile with elevated IFNG levels and a possible role of phagosome signaling compared with LP. Limitations: The study is descriptive and necessitates further investigation with larger cohorts and broader analyses. Conclusion: irLP differs from spontaneous LP on the clinical, histopathological, and gene expression level. The inflammatory gene signature in irLP suggests that topical JAK inhibitors could be an effective treatment, targeting local skin inflammation without systemic immunosuppression.

A murine model of peanut-allergic asthma.

Objectives: Peanut allergy is an IgE-mediated food allergy that is associated with asthma in certain patients. With increasing prevalence, its great impact on the quality of life, and a lack of treatment options, the need for new therapy options is a given. Hence, models for research and development are required. This study aimed to establish a murine model of allergic airway inflammation induced by peanut allergens. Methods: C3H mice were sensitised by intraperitoneal injections of peanut allergen extract and challenged by an intranasal application of the same extract. The assessment of airway inflammation involved the analysis of immune cells in the bronchoalveolar lavage fluid as measured by flow cytometry. Inflammatory reactions in the lung tissue were also studied by histology and quantitative PCR. Moreover, peanut-specific immune responses were studied after re-stimulation of spleen cells in vitro. Results: Sensitisation led to allergen-specific IgE, IgA, and IgG1 seroconversion. Subsequent nasal exposure led to allergic airway inflammation as manifested by structural changes such as bronchial smooth muscle hypertrophy, mucus cell hyperplasia, infiltration of eosinophil cells and T cells, as well as an upregulation of genes expressing IL-4, IL-5, IL-13, and IFN-γ. Upon re-stimulation of splenocytes with peanut allergen, increased secretion of both T-helper type 2 (Th2) and Th1 cytokines was observed. Conclusion: We successfully established a peanut-associated asthma model that exhibited many features characteristic of airway inflammation in human patients with allergic asthma. The model holds potential as a tool for investigating novel therapeutic approaches aimed at preventing the development of allergic asthma.

Cuticular Poroma: A Rare Poroma Variant Simulating a Malignant Neoplasm That Often Harbors YAP1::NUTM1 Fusions Similar to Their Conventional Counterparts.

ABSTRACT: Cuticular poroma is a rare variant of poroma composed of exclusively or predominantly cuticular cells, namely of large cells with ample eosinophilic cytoplasm. We report 7 cases of this rare tumor identified among 426 neoplasms diagnosed as poroma or porocarcinoma. The patients were 4 males and 3 females, ranging in age from 18 to 88 years. All presented with a solitary asymptomatic nodule. The location included knee (2 cases), shoulder, thigh, shin, lower arm, and neck (each 1). All lesions were surgically removed. No evidence of disease was observed in 5 patients with available follow-up (range 12-124 months).Microscopically, all neoplasms were composed of variably sized, focally closed packed, or interconnecting nodules constituted mostly of cuticular cells. Small poroid cells were a focal feature in 5 tumors, whereas in the remaining 2 cases, poroid cells with conspicuous but still in minority. Five neoplasms were somewhat asymmetric, with irregular outlines. Ductal differentiation and intracytoplasmic vacuoles were seen in 6 tumors. Other features variably encountered were conspicuous intranuclear pseudoinclusions, cystic change, occasional multinucleated cells, increased mitoses, and stromal desmoplasia. Four of the 5 tumors analyzed with next-generation sequencing yielded YAP1::NUTM1 fusions. In addition, various mutations, mostly of unknown significance were identified in one neoplasm.

Clinical Presentation and Prognostic Features in Patients with Immunotherapy-Induced Vitiligo-like Depigmentation: A Monocentric Prospective Observational Study.

Vitiligo-like depigmentation (VLD) is an immune-related adverse event (irAE) of checkpoint-inhibitor (CPI) treatment, which has previously been associated with a favourable outcome. The aim of this study was to explore clinical, biological and prognostic features of melanoma patients with VLD under CPI-treatment and to explore whether they exhibit a characteristic immune response profile in peripheral blood. Melanoma patients developing VLD under CPI were included in a prospective observational single-center cohort study. We collected and analysed clinical parameters, photographs and serum from 28 VLD patients. They received pembrolizumab (36%), nivolumab (11%), ipilimumab/nivolumab (32%) or clinical trial medications (21%). We performed a high-throughput proteomics assay (Olink), in which we identified a distinct proteomic signature in VLD patients in comparison to non-VLD CPI patients. Our clinical assessments revealed that VLD lesions had a predominantly symmetrical distribution pattern, with mostly smaller "freckle-like" macules and a preferential distribution in UV-exposed areas. Patients with previous targeted therapy showed a significantly longer time lapse between CPI initiation and VLD onset compared to non-pre-treated patients (12.5 vs. 6.25 months). Therapy responders exhibited a distinct proteomic profile when compared with non-responders in VLD such as upregulation of EDAR and downregulation of LAG3. ITGA11 was elevated in the VLD-group when compared to non-VLD-CPI-treated melanoma patients. Our findings demonstrate that on a proteomic level, VLD is characterized by a distinct immune signature when compared to CPI-treated patients without VLD and that therapy responsiveness is reflected by a characteristic immune profile. The pathomechanisms underlying these findings and how they could relate to the antitumoral response in melanoma remain to be elucidated.

Hypoxia and Ezrin Expression in Primary Melanoma Have High Prognostic Relevance.

Hypoxia affects tumor aggressiveness and activates pathways associated with epithelial mesenchymal transition (EMT) which are crucial for tumor progress. In this study, the correlation of hypoxia and EMT with sentinel lymph node status and tumor-specific survival was investigated in primary melanomas. CD34 for capillary count and Hypoxia inducible factor-1α (HIF-1α) as hypoxia indicators as well as Ezrin and L1-Cell Adhesion Molecule (L1CAM), both critical proteins contributing to EMT, were analyzed using immunohistochemistry in 49 melanoma patients with long follow-up (F/U, mean 110 months; range 12−263 months). We found a significant correlation between Breslow tumor thickness and Ezrin expression (p = 0.018). L1CAM expression in primary melanoma was significantly associated with HIF-1α expression (p < 0.0001) and sentinel lymph node metastasis (p = 0.011). Furthermore, low capillary count, reflecting hypoxic condition, was significantly associated with Ezrin expression (p = 0.047) and decreased tumor-specific survival (p = 0.035). In addition, patients with high Ezrin expression in their primary melanoma had a dramatic loss of life early in their F/U period (mean survival time 29 months; range 15−44 month). Our results highlight the relevance of Ezrin, L1CAM and HIF-1α as prognostic markers in melanoma patients. Additionally, we demonstrate that hypoxia in primary melanoma affects EMT and is at least partly responsible for early metastatic dissemination.

Granulomatous pigmented purpuric dermatosis: Clinical and histopathologic findings in a series of nine cases.

We report the largest case series to date of granulomatous pigmented purpuric dermatosis (GPPD), a rare variant of pigmented purpuric dermatoses (PPD). GPPD can cause diagnostic difficulties as it can be mistaken clinically and histopathologically with numerous inflammatory and infectious dermatoses or even cutaneous T-cell lymphoma. We compared the histopathological findings of nine cases of GPPD with a control group consisting of 10 randomly selected PPD of other subtypes. GPPD seems to predominantly affect the lower extremities of adult male patients; a clear association with hyperlipidemia or other systemic conditions could not be confirmed. Histopathologically, GPPD is characterized by a dermal histiocyte-rich interstitial infiltrate with or without granuloma formation, thickened capillaries, extravasated erythrocytes, and/or hemosiderin deposits. In contrast to other forms of PPD, the inflammatory infiltrate of GPPD can extend to the mid or deep dermis and the admixed lymphocytic infiltrate is mainly composed of CD8+ T-cells.

Photochemically-Mediated Inflammation and Cross-Presentation of Mycobacterium bovis BCG Proteins Stimulates Strong CD4 and CD8 T-Cell Responses in Mice.

Conventional vaccines are very efficient in the prevention of bacterial infections caused by extracellular pathogens due to effective stimulation of pathogen-specific antibodies. In contrast, considering that intracellular surveillance by antibodies is not possible, they are typically less effective in preventing or treating infections caused by intracellular pathogens such as Mycobacterium tuberculosis. The objective of the current study was to use so-called photochemical internalization (PCI) to deliver a live bacterial vaccine to the cytosol of antigen-presenting cells (APCs) for the purpose of stimulating major histocompatibility complex (MHC) I-restricted CD8 T-cell responses. For this purpose, Mycobacterium bovis BCG (BCG) was combined with the photosensitiser tetraphenyl chlorine disulfonate (TPCS2a) and injected intradermally into mice. TPCS2a was then activated by illumination of the injection site with light of defined energy. Antigen-specific CD4 and CD8 T-cell responses were monitored in blood, spleen, and lymph nodes at different time points thereafter using flow cytometry, ELISA and ELISPOT. Finally, APCs were infected and PCI-treated in vitro for analysis of their activation of T cells in vitro or in vivo after autologous vaccination of mice. Combination of BCG with PCI induced stronger BCG-specific CD4 and CD8 T-cell responses than treatment with BCG only or with BCG and TPCS2a without light. The overall T-cell responses were multifunctional as characterized by the production of IFN-γ, TNF-α, IL-2 and IL-17. Importantly, PCI induced cross-presentation of BCG proteins for stimulation of antigen-specific CD8 T-cells that were particularly producing IFN-γ and TNF-α. PCI further facilitated antigen presentation by causing up-regulation of MHC and co-stimulatory proteins on the surface of APCs as well as their production of TNF-α and IL-1ß in vivo. Furthermore, PCI-based vaccination also caused local inflammation at the site of vaccination, showing strong infiltration of immune cells, which could contribute to the stimulation of antigen-specific immune responses. This study is the first to demonstrate that a live microbial vaccine can be combined with a photochemical compound and light for cross presentation of antigens to CD8 T cells. Moreover, the results revealed that PCI treatment strongly improved the immunogenicity of M. bovis BCG.

Novel insights into the BAP1-inactivated melanocytic tumor.

BAP1-inactivated melanocytic tumor (BIMT) is a group of melanocytic neoplasms with epithelioid cell morphology molecularly characterized by the loss of function of BAP1, a tumor suppressor gene located on chromosome 3p21, and a mutually exclusive mitogenic driver mutation, more commonly BRAF. BIMTs can occur as a sporadic lesion or, less commonly, in the setting of an autosomal dominant cancer susceptibility syndrome caused by a BAP1 germline inactivating mutation. Owing to the frequent identification of remnants of a conventional nevus, BIMTs are currently classified within the group of combined melanocytic nevi. "Pure" lesions can also be observed. We studied 50 BIMTs from 36 patients. Most lesions were composed of epithelioid melanocytes of varying size and shapes, resulting extreme cytomorphological heterogeneity. Several distinctive morphological variants of multinucleated/giant cells were identified. Some hitherto underrecognized microscopic features, especially regarding nuclear characteristics included nuclear blebbing, nuclear budding, micronuclei, shadow nuclei, peculiar cytoplasmic projections (ant-bear cells) often containing micronuclei and cell-in-cell structures (entosis). In addition, there were mixed nests of conventional and BAP1-inactivated melanocytes and squeezed remnants of the original nevus. Of the 26 lesions studied, 24 yielded a BRAF mutation, while in the remaining two cases there was a RAF1 fusion. BAP1 biallelic and singe allele mutations were found in 4/22 and 16/24 neoplasms, respectively. In five patients, there was a BAP1 germline mutation. Six novel, previously unreported BAP1 mutations have been identified. BAP1 heterozygous loss was detected in 11/22 lesions. Fluorescence in situ hybridization for copy number changes revealed a related amplification of both RREB1 and MYC genes in one tumor, whereas the remaining 20 lesions studied were negative; no TERT-p mutation was found in 14 studied neoplasms. Tetraploidy was identified in 5/21 BIMTs. Of the 21 patients with available follow-up, only one child had a locoregional lymph node metastasis. Our results support a progression of BIMTs from a conventional BRAF mutated in which the original nevus is gradually replaced by epithelioid BAP1-inactivated melanocytes. Some features suggest more complex underlying pathophysiological events that need to be elucidated.

Cutaneous and systemic hyperinflammation drives maculopapular drug exanthema in severely ill COVID-19 patients.

BACKGROUND: Coronavirus disease-2019 (COVID-19) has been associated with cutaneous findings, some being the result of drug hypersensitivity reactions such as maculopapular drug rashes (MDR). The aim of this study was to investigate whether COVID-19 may impact the development of the MDR. METHODS: Blood and skin samples from COVID-19 patients (based on a positive nasopharyngeal PCR) suffering from MDR (COVID-MDR), healthy controls, non-COVID-19-related patients with drug rash with eosinophilia and systemic symptoms (DRESS), and MDR were analyzed. We utilized imaging mass cytometry (IMC) to characterize the cellular infiltrate in skin biopsies. Furthermore, RNA sequencing transcriptome of skin biopsy samples and high-throughput multiplexed proteomic profiling of serum were performed. RESULTS: IMC revealed by clustering analyses a more prominent, phenotypically shifted cytotoxic CD8+ T cell population and highly activated monocyte/macrophage (Mo/Mac) clusters in COVID-MDR. The RNA sequencing transcriptome demonstrated a more robust cytotoxic response in COVID-MDR skin. However, severe acute respiratory syndrome coronavirus 2 was not detected in skin biopsies at the time point of MDR diagnosis. Serum proteomic profiling of COVID-MDR patients revealed upregulation of various inflammatory mediators (IL-4, IL-5, IL-6, TNF, and IFN-γ), eosinophil and Mo/Mac -attracting chemokines (MCP-2, MCP-3, MCP-4 and CCL11). Proteomics analyses demonstrated a massive systemic cytokine storm in COVID-MDR compared with the relatively milder cytokine storm observed in DRESS, while MDR did not exhibit such features. CONCLUSION: A systemic cytokine storm may promote activation of Mo/Mac and cytotoxic CD8+ T cells in severe COVID-19 patients, which in turn may impact the development of MDR.

Primary Localized Cutaneous Amyloidosis: A Retrospective Study of an Uncommon Skin Disease in the Largest Tertiary Care Center in Switzerland.

BACKGROUND: Primary localized cutaneous amyloidosis (PLCA) is defined by the deposition of amyloid protein in the skin without systemic involvement. There are four subtypes of PLCA: lichen amyloidosis (LA), macular amyloidosis (MA), biphasic amyloidosis (BA), and nodular amyloidosis (NA). PLCA occurs most frequently in Latin Americans and Asians. Treatment is not standardized. OBJECTIVES: To identify subtypes, demographic and clinical features and treatment efficacy in patients with histopathologically confirmed PLCA. MATERIALS AND METHODS: Data of PLCA patients were extracted from the electronic hospital database and included if diagnosis of PLCA was histopathologically confirmed and if sufficient information regarding treatment and follow-up was available. The evaluation of the treatment efficacy was based on a novel score to assess the reduction of itch and skin lesions. RESULTS: In this retrospective, monocentric study, 37 cases of PLCA diagnosed between 2000 and 2020 were included (21 females) with a mean age of 52 years. LA was the most frequent subtype found in 21 patients (56.8%), followed by MA in 10 patients (28%) and BA in 6 patients (16.2%). No cases of NA were included. 22 patients (59.4%) had skin phototype II or III. Regarding treatment, a combination of UVA1 phototherapy with high-potency topical corticosteroids seemed to show the highest efficacy with complete clearance of symptoms in 4 patients (10.8%). A substantial improvement of symptoms was found in 5 patients (12.7%) treated with high-potency topical corticosteroids alone or in combination either with UVA1 or bath PUVA or monotherapy with UVA1 phototherapy or capsaicin (0.075%) cream. Low-/medium-potency topical corticosteroids alone or in combination with UVBnb (311 nm) phototherapy showed a lower efficacy. CONCLUSION: Our data show that PCLA is a rare disease in central Europe but can also be expected in a predominantly Caucasian population. The best treatment response was achieved with a combination of UVA1 phototherapy and high-potency topical corticosteroids.

Trichoblastoma: A Consecutive Series of 349 Sporadic Cases Analyzed by Ackerman Subtypes.

ABSTRACT: Trichoblastoma (TB) is a benign biphasic follicular neoplasm with differentiation toward the germinative cells and a specific follicular mesenchyme. We subtyped 349 sporadic TB according to a classification proposed by Ackerman. Two hundred forty-six (246/349, 70.5%) neoplasms were comprised of mixed subtypes. TB composed exclusively of a single pattern was less common (103/349, 29.5%). The most common pure subtype was cribriform TB followed by small nodular TB. Twelve cases (12/349, 3.4%) had unique features and are reported herein as novel histopathologic subtypes of the neoplasm.

A Problem of Classification: 2 Cases of Epstein-Barr Virus + Primary Cutaneous Plasmacytoma Arising in Immunocompetent Elderly Patients.

ABSTRACT: Primary extramedullary plasmacytoma is rare monoclonal proliferation of plasma cells, which arise in various nonosseous anatomic locations without detectable underlying systemic disease. Historically, cutaneous infiltrates rich in mature neoplastic plasma cells have fallen into one of the following categories, plasmacytoma, lymphoplasmacytic lymphoma, and marginal zone lymphoma, which included immunocytoma. Since 2005, each of these was subsumed under the marginal zone lymphoma umbrella, largely on the basis of acknowledged diagnostic difficulties in some of these cases. We describe 2 cases in which the cutaneous infiltrates consisted of a pure population of light chain-restricted mature plasma cells in the absence of any other evidence for a marginal zone proliferation, or evidence of extracutaneous involvement, including a paraprotein. We propose that primary cutaneous plasmacytoma is the accurate diagnosis and is consistent with wider nomenclature. The unusual observation of widespread Epstein-Barr virus expression in both tumors is also discussed.

Photochemical internalization (PCI)-mediated activation of CD8 T cells involves antigen uptake and CCR7-mediated transport by migratory dendritic cells to draining lymph nodes.

Antigen cross-presentation to cytotoxic CD8+ T cells is crucial for the induction of anti-tumor and anti-viral immune responses. Recently, co-encapsulation of photosensitizers and antigens into microspheres and subsequent photochemical internalization (PCI) of antigens in antigen presenting cells has emerged as a promising new strategy for inducing antigen-specific CD8+ T cell responses in vitro and in vivo. However, the exact cellular mechanisms have hardly been investigated in vivo, i.e., which cell types take up antigen-loaded microspheres at the site of injection, or in which secondary lymphoid organ does T cell priming occur? We used spray-dried poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with ovalbumin and the photosensitizer tetraphenyl chlorine disulfonate (TPCS2a) to investigate these processes in vivo. Intravital microscopy and flow cytometric analysis of the murine ear skin revealed that dendritic cells (DCs) take up PLGA microspheres in peripheral tissues. Illumination then caused photoactivation of TPCS2a and induced local tissue inflammation that enhanced CCR7-dependent migration of microsphere-containing DCs to tissue-draining lymph nodes (LNs), i.e., the site of CD8+ T cell priming. The results contribute to a better understanding of the functional mechanism of PCI-mediated vaccination and highlight the importance of an active transport of vaccine microspheres by antigen presenting cells to draining LNs.

Glucocorticoid Receptor Beta and Its Prognostic Value on Treatment Response in Chronic Vulvar Dermatitis.

BACKGROUND: Chronic vulvar dermatitis (CVD) is the most prevalent disease in gynecologic dermatology. The treatment mainly depends on topical glucocorticoids (TGC) but is challenged by insufficient treatment response. On a histological level, the upregulation of the glucocorticoid receptor ß (GRß), an inhibitor of the active glucocorticoid receptor α (GRα), is discussed as mechanism of glucocorticoid insensitivity. OBJECTIVES: To analyze whether the expression of GRß protein at baseline in keratinocytes may predict responsiveness to TGC in patients with CVD. METHODS: In this retrospective cohort study, clinical and biological data of 25 women with a histological diagnosis of chronic vulvar eczema were analyzed. Randomization was done according to the responsiveness to TGC treatment (responsive vs. nonresponsive). Clinical data and the expression of GRß in the immunohistochemical stained biopsies were examined. RESULTS: Fifty-two percent of women with CVD were nonresponsive to TGC. GRß was abundantly expressed in the cytoplasma of keratinocytes of the vulvar epithelium, but no difference in the level of expression was found among GC responsive and nonresponsive patients in the semiquantitative (p = 0.376) and quantitative analysis (p = 0.894). CONCLUSION: GRß is highly expressed in keratinocytes of the vulvar epidermis affected by CVD, but GRß expression was not increased in patients nonresponsive to TGC compared to responsive patients. Thus, the failure mechanism in nonresponders still remains to be elucidated.

Lichen aureus with pseudolymphomatous infiltrate.

Lichen aureus is a variant of pigmented purpuric dermatoses. The usual histopathology of lichen aureus is characterized by a subepidermal dense, band-like lymphocytic infiltrate, extravasated erythrocytes, and hemosiderin deposits. We report three patients with lichen aureus on the extremities with similar clinical, dermoscopic, and histopathological findings characterized by a dense band-like relatively deep dermal infiltrate accompanied by extravasation of erythrocytes and hemosiderin deposits occasioning a resemblance to a lymphoproliferative disorder.