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Topic review
Updated time: 25 May 2021
Submitted by: Jag Bhawan
Definition: Interface dermatitis is a pathological pattern characterized by the presence of basal cell vacuolization and apoptotic keratinocytes. A variety of dermatoses exhibit interface dermatitis on pathology including the lichenoid dermatoses, graft versus host disease, connective tissue diseases, and drug reactions, among others. Several entities of interface dermatitides are known to have distinct rare adnexotropic variants whereby the inflammation involves the adnexa of the skin such as the hair follicle or the sweat gland. In lichen planus for example, follicular and syringotropic variants have been classically described. Adnexal involvement can also at times be seen on histopathology of the interface dermatitides that do not have distinct adnexotropic variants. For example, adnexal inflammation can be seen in lichen striatus or in pityriasis lichenoides.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 24 Jun 2021
Submitted by: Stephan Schreml
Definition: The acid-sensing ion channels ASIC1 and ASIC2, as well as the transient receptor potential vanilloid channels TRPV1 and TRPV4, are proton-gated cation channels that can be activated by low extracellular pH (pHe), which is a hallmark of the tumor microenvironment in solid tumors. However, the role of these channels in the development of skin tumors is still unclear.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 23 Jun 2021
Submitted by: Margaret Ottaviano
Definition: As widely acknowledged, 40–50% of all melanoma patients harbour an activating BRAF mutation (mostly BRAF V600E). The identification of the RAS–RAF–MEK–ERK (MAP kinase) signalling pathway and its targeting has represented a valuable milestone for the advanced and, more recently, for the completely resected stage III and IV melanoma therapy management. However, despite progress in BRAF-mutant melanoma treatment, the two different approaches approved so far for metastatic disease, immunotherapy and BRAF+MEK inhibitors, allow a 5-year survival of no more than 60%, and most patients relapse during treatment due to acquired mechanisms of resistance. Deep insight into BRAF gene biology is fundamental to describe the acquired resistance mechanisms (primary and secondary) and to understand the molecular pathways that are now being investigated in preclinical and clinical studies with the aim of improving outcomes in BRAF-mutant patients.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 23 Jun 2021
Submitted by: Ivan Litvinov
Definition: In advanced melanoma, BRAF mutation testing is critical in predicting treatment response with targeted therapy (i.e., BRAF/MEK inhibitors). Certain features were identified in melanomas that harbor BRAF mutations (e.g., primary lesions located on the trunk, diagnosed in patients <50, visibly pigmented tumors and, at times, with ulceration or specific dermatoscopic features). For select advanced melanoma patients, delays in determining mutational status present a significant barrier to the prompt initiation of treatment. This can adversely impact patient outcomes, especially in the metastatic setting due to a rapidly progressive disease. Treatment in these cases needs to start promptly by a medical oncologist. Ordering BRAF testing by preceding members of the treating team will allow medical oncologists to initiate treatment at the first visit. According to poor survival outcomes, we propose that patients with thick tumors (>4.0 mm) or >2 mm tumors with ulceration (i.e., stage ≥IIB) should potentially be considered for systemic therapy, thus justifying reflex BRAF testing.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 10 May 2021
Submitted by: Carmen de Jesús Gil
Definition: Psoriasis is a T cell-mediated skin disease resulting from epithelial and immunological cells’ interactions, which affects around 2% of the population worldwide. Its onset is influenced by genetic and environmental factors, particularly infections among which Streptococcus pyogenes is the best characterized. However, the commensal fungusCandida albicans has been also associated to triggering psoriasis. Here we discuss what it is known about the link betweeen Candida and psoriasis pathogenesis.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 25 May 2021
Submitted by: Dimitri Kasakovski
Definition: Cutaneous Melanoma (CM), arising from pigment-producing melanocytes in the skin, is an aggressive cancer with high metastatic potential. While cutaneous melanoma represents only a fraction of all skin cancers (<5%), it accounts for most skin-cancer-related deaths worldwide. Immune checkpoint inhibition has been the first therapeutic approach to significantly benefit patient survival after treatment. Nevertheless, the immunosuppressive tumor microenvironment and the intrinsic and acquired treatment resistance of melanoma remain crucial challenges. Combining local and systemic treatment offers the potential to augment therapeutic response and overcome resistance, although, complex drug combinations can harbor an increased risk of immune-related adverse events.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 25 Jun 2021
Submitted by: Philippe Grange
Definition: Cutibacterium acnes is a member of the skin microbiota found predominantly in regions rich in sebaceous glands. It is involved in maintaining healthy skin and has long been considered a commensal bacterium. Its involvement in various infections has led to its emergence as an opportunist pathogen. Interactions between C. acnes and the human host, including the human skin microbiota, promote the selection of C. acnes strains capable of producing several virulence factors that increase inflammatory capability. This pathogenic property may be related to many infectious mechanisms, such as an ability to form biofilms and the expression of putative virulence factors capable of triggering host immune responses or enabling C. acnes to adapt to its environment. During the past decade, many studies have identified and characterized several putative virulence factors potentially involved in the pathogenicity of this bacterium. These virulence factors are involved in bacterial attachment to target cells, polysaccharide-based biofilm synthesis, molecular structures mediating inflammation, and the enzymatic degradation of host tissues. C. acnes, like other skin-associated bacteria, can colonize various ecological niches other than skin. It produces several proteins or glycoproteins that could be considered to be active virulence factors, enabling the bacterium to adapt to the lipophilic environment of the pilosebaceous unit of the skin, but also to the various organs it colonizes.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 17 Mar 2021
Submitted by: Woong Mo Yang
Definition: Atopic dermatitis (AD) is a chronic cutaneous disorder that is characterized by severe eczematous inflammation, swelling, and lichenification. Activation of T helper (Th)-22 cells by allergens leads to epidermal hyperplasia with hyperkeratosis at the chronic phase of AD. Derma-Hc is composed of five natural herbs with anti-AD effects, such as Astragalus membranaceus BUNGE, Schizonepeta tenuifolia Briq., Cryptotympana pustulata Fabr., Angelica sinensis Diels, Arctium lappa L. In this study, the ameliorative effect of Derma-Hc on cutaneous lichenification in 2,4-dinitrochlorobenzne (DNCB)-induced AD was investigated. The dorsal skin of mice was sensitized with DNCB to induce AD-like skin lesions. The dermatitis score and frequency of scratching were evaluated. Thickness of epidermis and dermis was measured by staining with H&E. In addition, infiltration of the mast cell was observed by staining with toluidine blue. Then, desmosomal cadherin, DSC1 was examined by immunofluorescence. Pathological mechanisms involved in lichenification were analyzed in AD-like skin lesions and TNF-α + IFN-γ-treated with human keratinocytes including keratinocyte differentiation genes and JAK1-STAT3 signaling pathway with IL-22 by RT-PCR and western blotting. Topical treatment of Derma-Hc improved AD-like symptoms such as dryness, edema and lichenefication and decreased the number of scratches. Histopathological analysis demonstrated that Derma-Hc significantly inhibited epidermal hyperplasia, hyperkeratosis, and mast cells infiltration.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 19 May 2021
Submitted by: Roberto Cuomo
Definition: BIA-ALCL is a rare T-cell lymphoma, CD30 positive, ALK-negative usually discovered after the diagnosis of spontaneous periprosthetic seroma or intracapsular mass around the breast implant.
Entry Collection : Skin Pathologies
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Topic review
Updated time: 14 Jul 2021
Submitted by: Alina Kurylowicz
Definition: Skin aging is associated with the accumulation of senescent cells and is related to many pathological changes, including decreased protection against pathogens, increased susceptibility to irritation, delayed wound healing, and increased cancer susceptibility. Senescent cells secrete a specific set of pro-inflammatory mediators, referred to as a senescence-associated secretory phenotype (SASP), which can cause profound changes in tissue structure and function. Thus, drugs that selectively eliminate senescent cells (senolytics) or neutralize SASP (senostatics) represent an attractive therapeutic strategy for age-associated skin deterioration. There is growing evidence that plant-derived compounds (flavonoids) can slow down or even prevent aging-associated deterioration of skin appearance and function by targeting cellular pathways crucial for regulating cellular senescence and SASP. This review summarizes the senostatic and senolytic potential of flavonoids in the context of preventing skin aging.
Entry Collection : Skin Pathologies
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