Neutrophilic dermatosis: disease mechanism and treatment

From the Deep: Overlap of Neutrophilic Dermatoses Disorders Associated With Acute Myeloid Leukemia

We report the case of a man in his 50s with refractory acute myelomonocytic leukaemia (AML) who presented with neck swelling, fever, and elevated levels of C-reactive protein (CPR) after venous punctures. An infected haematoma was presumed, but the patient showed no signs of improvement under broad-range antibiotics, and microbiological results were negative. The subsequent development of a rapidly evolving erythematous-violaceous plaque around a site that had previously punctured on the extensor surface of the right arm prompted us to reconsider the clinical setting as a whole and consider the hypothesis of deep neutrophilic dermatosis (ND) associated with haematologic malignancy. A biopsy of the arm lesion showed an aseptic neutrophilic infiltrate, confirming this diagnosis. The patient was initially treated with high-dose intravenous corticosteroids, resulting in a dramatic improvement of the skin lesions.

Immune-Mediated Cutaneous Paraneoplastic Syndromes Associated With Hematologic Malignancies: Skin as a Mirror of Hematologic Neoplasms

Malignant neoplasms may present as paraneoplastic syndromes with mucocutaneous manifestations, which may or may not be chronologically associated. The pathophysiological mechanism is complex and not completely understood; therefore, definitive diagnosis may be achieved with a precise differential diagnosis based on the morphology of skin lesions, clinical picture, and histological pattern. The complexities, and low frequency, make the therapeutic approach quite challenging; consequently, the cornerstone of therapy is the eradication of the underlying neoplasms. Corticosteroids are the therapy of choice for most of these immune-mediated manifestations, but for the most part, the successful resolution requires the eradication of the underlying malignancy.

Inflammatory and Immune Disorders Associated with Myelodysplastic Syndromes

Systemic auto-inflammatory or autoimmune diseases (SIADs) develop in up to a quarter of patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). With or without the occurrence of SIADs, the distribution of MDS subtypes and the international or CMML-specific prognostic scoring systems have been similar between MDS/CMML patients. Moreover, various SIADs have been described in association with MDS, ranging from limited clinical manifestations to systemic diseases affecting multiple organs. Defined clinical entities including systemic vasculitis, connective tissue diseases, inflammatory arthritis and neutrophilic diseases are frequently reported; however, unclassified or isolated organ impairment can also be seen. Although the presence of SIADs does not impact the overall survival nor disease progression to acute myeloid leukemia, they can help with avoiding steroid dependence and make associated adverse events of immunosuppressive drugs challenging. While therapies using steroids and immunosuppressive treatment remain the backbone of first-line treatment, increasing evidence suggests that MDS specific therapy (hypomethylating agents) and sparing steroids may be effective in treating such complications based on their immunomodulatory effect. The aim of this review was to analyze the epidemiological, pathophysiological, clinical and therapeutic factors of systemic inflammatory and immune disorders associated with MDS.

Inflammatory arthritis-associated pyoderma gangrenosum: a systematic review

INTRODUCTION/OBJECTIVES

Pyoderma gangrenosum (PG) is a rare, rapidly progressive neutrophilic dermatosis commonly associated with systemic inflammatory diseases. We aimed to characterize the association of PG and inflammatory arthritis, as little is known outside of case reports and small cohort studies.

METHOD

We performed a systematic review in PubMed, EMBASE, and Scopus from inception to present using the terms arthritis and pyoderma gangrenosum. Patient demographics, clinical presentation, and treatment outcomes were recorded. Descriptive statistics and stratified analysis were used to compare factors of interest by type of arthritis.

RESULTS

A total of 1399 articles were screened, and 129 patients with inflammatory arthritis and PG were included in the review. The most common types of arthritis were rheumatoid arthritis (RA) (50.4%), inflammatory bowel disease (IBD)-associated arthritis (10.9%), and psoriatic arthritis (8.5%). In the vast majority of cases, joint symptoms preceded PG, by a median of 10 years (inter-quartile range [IQR] 5-16). Corticosteroid monotherapy and biologic therapies, used alone or in combination, resulted in improvement or complete resolution of ulcers 71.4% and 67.3% of the time, respectively. Within the latter, infliximab, adalimumab, and anakinra were most successful in inducing remission overall. RA and non-RA did not differ significantly in treatment success or healing time.

CONCLUSIONS

This study shows that PG is frequently preceded by inflammatory arthritis, most commonly RA. Clinicians used a wide variety of treatment regimens with variable outcomes. While larger studies are needed to standardize the treatment of inflammatory arthritis-associated PG, this study suggests that in addition to systemic corticosteroids, biologic medications can be effective treatment options for these patients.

KEY POINTS

• Inflammatory arthritis, most commonly rheumatoid arthritis, often precedes rather than follows pyoderma gangrenosum. • Other forms of arthritis associated with PG included IBD-associated arthritis and psoriatic arthritis. • Biologic therapies, such as infliximab, adalimumab, and anakinra, were largely successful in treating arthritis-associated pyoderma gangrenosum and may play an important role in corticosteroid-sparing therapy or in a maintenance regimen for this subset of patients. • The type of inflammatory arthritis associated with pyoderma gangrenosum may not be a helpful treatment guide as it was not significantly associated with treatment outcomes or healing time.

Immune-Mediated Dermatoses in Patients with Haematological Malignancies: A Comprehensive Review

Haematological malignancies induce important alterations of the immune system, which account for the high frequency of autoimmune complications observed in patients. Cutaneous immune-mediated diseases associated with haematological malignancies encompass a heterogeneous group of dermatoses, including, among others, neutrophilic and eosinophilic dermatoses, autoantibody-mediated skin diseases, vasculitis and granulomatous dermatoses. Some of these diseases, such as paraneoplastic pemphigus, are associated with an increased risk of death; others, such as eosinophilic dermatoses of haematological malignancies, run a benign clinical course but portend a significant negative impairment on a patient’s quality of life. In rare cases, the skin eruption reflects immunological alterations associated with an unfavourable prognosis of the associated haematological disorder. Therapeutic management of immune-mediated skin diseases in patients with haematological malignancies is often challenging. Systemic corticosteroids and immunosuppressive drugs are considered frontline therapies but may considerably augment the risk of serious infections. Indeed, developing a specific targeted therapeutic approach is of crucial importance for this particularly fragile patient population. This review provides an up-to-date overview on the immune-mediated skin diseases most frequently encountered by patients with onco-haematological disorders, discussing new pathogenic advances and therapeutic options on the horizon.

Subcorneal pustular dermatosis: Comprehensive review and report of a case presenting during pregnancy

Subcorneal pustular dermatosis (SPD), also known as Sneddon-Wilkinson disease, is a rare, relapsing, sterile pustular eruption of unknown etiology that develops most commonly in middle-aged or mature women. This article reviews the presentation, associations, and management of the condition and highlights advances in pathophysiology. Onset of SPD during pregnancy has not been reported. Herein, we report a case of SPD that developed during pregnancy. The patient was treated with dapsone without complications for her or the fetus. An association between T helper (Th) 17 and Th2 environments in the development of SPD has been advocated. Pregnancy is characterized by a predominance of Th2 responses and increased interleukin-17 levels and thus may favor the development of the condition.

Recurrent oral ulceration: Etiology, classification, management, and diagnostic algorithm

Recurrent oral ulcerations are manifestations of a heterogeneous set of both general and more-or-less specific oral diseases due to numerous potential etiologies, including, but not limited to, infections, medications, autoimmune disease, and other systemic disease. This review discusses the pathogenesis, clinical presentation, diagnosis, and management of the common causes of recurrent oral ulceration. The following types/etiologies of recurrent oral ulceration are covered: traumatic ulceration, chemical ulceration, recurrent aphthous stomatitis, medication-related ulceration, infectious ulceration, mucocutaneous disease, and autoimmune/systemic disease. A diagnostic algorithm for recurrent oral ulceration is also presented.

Leukemia Cutis in Chronic Neutrophilic Leukemia Associated with Colony Stimulating Factor 3 Receptor Mutation: Clinical Severity Paralleled with Hematologic Abnormality

Cutaneous lesions of leukemia cutis (LC) by chronic neutrophilic leukemia (CNL) have been merely reported due to the rare occurrences of CNL. Furthermore cutaneous lesions in relation to clinical severity have been far less studied. A 70-year-old man presented with multiple violaceous papules and excoriations on both lower extremities. The diagnosis was LC based on histologic and laboratory evaluation and the origin was elaborated as CNL with the confirmation of colony stimulating factor 3 receptor (CSF3R) mutation. Interestingly, the patient presented clinical severity in a parallel manner to the hematologic abnormality. To the best of our knowledge, there has been no reported case of CSF3R confirmed LC in CNL featuring explicit skin eruption in relation to laboratory findings.

The role of mixed Mycoplasma and Herpesvirus infections in case of skin lesions in children

Numerous literature data show the role of mycoplasma infection in the development of non-respiratory lesions of various organs and systems, including the skin. Herpesvirus and mycoplasma infections can trigger the development of immune-mediated inflammatory reactions of the skin and mucous membranes — erythema multiforme exudative, Stevens-Johnson syndrome, vesicular pustular dermatosis — Sneddon-Wilkinson syndrome, etc.

In order to study the frequency and nature of skin lesions with mycoplasmosis combined with herpesvirus infection, 45 patients aged 3 to 15 years of life were observed. A comprehensive clinical and laboratory study revealed skin lesions in 27 patients associated with current mycoplasma and herpesvirus infections. Thus, multiforme exudative erythema in the small form variant was diagnosed in 13 patients, skin vasculitis in 4, hemorrhagic purpura in 3, urticaria rash in 3, erythema nodosum in 2, mucositis in 2 children. In 18 children, a combined mycoplasma and herpesvirus infection was established. In 9 children, a mono infection was detected (in 5 — herpes virus and in 4 — mycoplasma).

All observed patients showed antibodies to smooth muscle antigens in titers from 1:80 to 1:160 (normal 1:40) and in the vast majority (in 24 patients) — antibodies to vascular endothelial antigens in titers from 1:80 to 1:320 (with the norm of 1:40). Compaction of the intima-media complex was detected in 6 patients with monoinfection and in 16 patients with co-infection, according to ultrasound duplex scanning of the vessels of the brachiocephalic department.

Thus, for various immuno-inflammatory, allergic skin diseases, screening for infections, in particular, mycoplasma and herpesvirus, is necessary to optimize treatment.

Neutrophilic Dermatoses Associated with Myeloid Malignancies

Neutrophilic dermatoses (ND) are a group of conditions characterized by an aseptic accumulation of polymorphonuclear leukocytes in the skin. Occurrence of ND in association with myeloid malignancies, mainly myelodysplastic syndrome and myelogenous acute leukemia, is not rare and is often associated with a poor prognosis. Recent findings have improved understanding of the pathophysiology of myeloid malignancy-associated ND. We review the clinical spectrum of myeloid malignancy-associated ND with an emphasis on recently identified mechanisms. Myeloid leukemia cells retain the potential for terminal differentiation into polymorphonuclear leukocytes in the skin. Many studies suggest a clonal link between myeloid malignancies and ND. Activation of autoinflammatory pathways (NOD-like receptor family pyrin domain-containing-3, Familial Mediterranean Fever Gene) in the clonal cells of myeloid disorders may also be involved in this setting.

Skin and Systemic Inflammation in Schnitzler's Syndrome Are Associated With Neutrophil Extracellular Trap Formation

Schnitzler's syndrome is a rare autoinflammatory disorder characterized by interleukin-1ß-mediated and neutrophil-dominated inflammation. Neutrophil extracellular traps (NETs) are web-like structures of decondensed chromatin, histones, and antimicrobial peptides released by neutrophils. NETs were initially described in the context of pathogen defense but are also involved in autoimmune-mediated skin diseases. Here, we assessed the role of neutrophil extracellular trap formation (NETosis) in Schnitzler's syndrome. Immunofluorescence co-staining of myeloperoxidase and subnucleosomal complex was performed on lesional skin samples from patients with Schnitzler's syndrome, other neutrophilic dermatoses (cryopyrin-associated periodic syndrome, Sweet syndrome, and pyoderma gangrenosum), urticarial vasculitis and chronic spontaneous urticaria as well as healthy control skin. Blood neutrophils from patients with Schnitzler's syndrome and controls were isolated, and NETosis was induced by phorbol 12-myristate 13-acetate (PMA). Also, NETosis of control neutrophils induced by symptomatic Schnitzler's syndrome sera, cytokines and sub-threshold PMA doses was studied. Immunofluorescence co-staining revealed widespread and substantial NET formation in lesional skin of Schnitzler's syndrome patients but absence of NETs in chronic spontaneous urticaria and control skin. Neutrophils undergoing NETosis were observed in the skin of other neutrophilic diseases too. Correspondingly, blood neutrophils from Schnitzler's syndrome patients showed significantly elevated NETosis rates compared to control neutrophils following stimulation with PMA. Increased NETosis correlated well with high levels of C-reactive protein (CRP). SchS patients with the lowest NETosis rates had persistent joint and bone pain despite IL-1 blockade. Stimulation of control neutrophils and sub-threshold PMA with sera of symptomatic Schnitzler's syndrome patients disclosed enhanced NETosis as compared to control sera. Our results suggest that the induction of NET formation by neutrophils contributes to skin and systemic inflammation and may support the resolution of local inflammation in Schnitzler's syndrome.

Neutrophilic dermatoses: Kids are not just little people

Neutrophilic dermatoses are a group of inflammatory skin disorders characterized by an overactive innate immune system with dysregulation of neutrophils without underlying infectious etiology. The major representative conditions discussed are Sweet syndrome; pyoderma gangrenosum; neutrophilic eccrine hidradenitis; palmoplantar eccrine hidradenitis; subcorneal pustular dermatoses; bowel-associated dermatosis arthritis syndrome; and synovitis, acne, pustulosis, hyperostosis, and osteitis. We will also discuss other neutrophilic conditions present almost exclusively in the pediatric population, including congenital erosive and vesicular dermatosis with reticulated supple scarring and the recently described group of autoinflammatory diseases. The clinical characteristics, diagnostic approach, and treatment management in the pediatric and adult population are discussed.

Tumor Necrosis Factor-α and IL-17A Activation Induces Pericyte-Mediated Basement Membrane Remodeling in Human Neutrophilic Dermatoses

Sweet syndrome (SS) is a prototypical neutrophilic dermatosis, a class of inflammatory diseases marked by elevated levels of tumor necrosis factor (TNF)-α and IL-17A, pathologic neutrophil recruitment, and microvascular remodeling. Histologic analyses of four matrix proteins-collagen I and IV, laminin, and fibronectin-in skin biopsies of patients with SS reveal that the basement membrane of dermal postcapillary venules undergoes changes in structure and composition. Increased neutrophil recruitment in vivo was associated with increases in collagen IV, decreases in laminin, and varied changes in fibronectin. In vitro studies using TNF-α and IL-17A were conducted to dissect basement membrane remodeling. Prolonged dual activation of cultured human pericytes with TNF-α and IL-17A augmented collagen IV production, similar to in vivo remodeling. Co-activation of pericytes with TNF-α and IL-17A also elevated fibronectin levels with little direct effect on laminin. However, the expression of fibronectin- and laminin-specific matrix metalloproteinases (MMPs), particularly MMP-3, was significantly up-regulated. Interactions between pericytes and neutrophils in culture yielded even higher levels of active MMPs, facilitating fibronectin and laminin degradation, and likely contributing to the varied levels of detectable fibronectin and the decreases in laminin observed in vivo. These data indicate that pericyte-neutrophil interactions play a role in mediating microvascular changes in SS and suggest that targeting MMP-3 may be effective in protecting vascular wall integrity.

Sweet syndrome presenting as a febrile rash in a returning traveller

Sweet syndrome was discovered in 1964 and is now well described in the dermatology literature. Knowledge of this unique febrile and painful dermatosis is important for the emergency physician because the syndrome can be readily identified and is extremely responsive to oral steroid therapy. Early diagnosis can greatly improve patient satisfaction and avoid days of ineffective treatment. An accurate and timely diagnosis of Sweet syndrome is also important to guide investigation into a number of associated diseases.

Subcorneal Pustular Dermatosis: A Review of 30 Years of Progress

Subcorneal pustular dermatosis (SPD), also known as Sneddon-Wilkinson disease, is a rare, benign yet relapsing pustular dermatosis. Its incidence and prevalence have not been well studied. It characteristically presents as hypopyon pustules on the trunk and intertriginous areas of the body. SPD is similar to two other disease entities. Both SPD-type immunoglobulin (Ig)-A pemphigus and annular pustular psoriasis clinically and histologically present similarly to SPD. Immunologic studies separate SPD-type IgA pemphigus from SPD and pustular psoriasis. However, there is still an unclear designation as to whether SPD is its own entity distinct from pustular psoriasis, as the once thought characteristic histologic picture of psoriasis does not hold true for pustular psoriasis. SPD has been reported to occur in association with several neoplastic, immunologic, and inflammatory conditions. Dapsone remains the first-line treatment for SPD, although dapsone-resistant cases have been increasingly reported. Other therapies have been used singly or as adjunctive therapy with success, such as corticosteroids, immunosuppressive agents, tumor necrosis factor inhibitors, and ultraviolet light therapy. This article provides a review of the last 30 years of available literature, with a focus on successful treatment options and a suggestion for reappraisal of the classification of SPD.

The Role of Interleukin-1 in Inflammatory and Malignant Human Skin Diseases and the Rationale for Targeting Interleukin-1 Alpha

Inflammation plays a major role in the induction and progression of several skin diseases. Overexpression of the major epidermal proinflammatory cytokines interleukin (IL) 1 alpha (IL-1α) and 1 beta (IL-1β) is positively correlated with symptom exacerbation and disease progression in psoriasis, atopic dermatitis, neutrophilic dermatoses, skin phototoxicity, and skin cancer. IL-1β and the interleukin-1 receptor I (IL-1RI) have been used as a therapeutic target for some autoinflammatory skin diseases; yet, their system-wide effects limit their clinical usage. Based on the local effects of extracellular IL-1α and its precursor, pro-IL-1α, we hypothesize that this isoform is a promising drug target for the treatment and prevention of many skin diseases. This review provides an overview on IL-1α and IL-β functions, and their contribution to inflammatory and malignant skin diseases. We also discuss the current treatment regimens, and ongoing clinical trials, demonstrating the potential of targeting IL-1α, and not IL-1β, as a more effective strategy to prevent or treat the onset and progression of various skin diseases.

Neutrophils in animal models of autoimmune disease

Neutrophils have traditionally been thought to play only a peripheral role in the genesis of many autoimmune and inflammatory diseases. However, recent studies in a variety of animal models suggest that these cells are central to the initiation and propagation of autoimmunity. The use of mouse models, which allow either deletion of neutrophils or the targeting of specific neutrophil functions, has revealed the many complex ways these cells contribute to autoimmune/inflammatory processes. This includes generation of self antigens through the process of NETosis, regulation of T-cell and dendritic cell activation, production of cytokines such as BAFF that stimulate self-reactive B-cells, as well as indirect effects on epithelial cell stability. In comparing the many different autoimmune models in which neutrophils have been examined, a number of common underlying themes emerge - such as a role for neutrophils in stimulating vascular permeability in arthritis, encephalitis and colitis. The use of animal models has also stimulated the development of new therapeutics that target neutrophil functions, such as NETosis, that may prove beneficial in human disease. This review will summarize neutrophil contributions in a number of murine autoimmune/inflammatory disease models.

Histiocytoid Sweet's syndrome in a patient with myelodsyplastic syndrome: report and review of the literature

The neutrophilic dermatoses are a group of disorders characterized by skin lesions for which histological examination reveals intense epidermal and/or dermal inflammatory infiltrates composed primarily of neutrophils without evidence of infection. The myelodysplastic syndromes consist of a heterogeneous group of malignant hematopoietic stem cell disorders characterized by dysplastic and inadequate blood cell production with a variable risk of transformation to acute leukemia. Rarely, histiocytoid Sweet's syndrome occurring in patients with myelodysplastic syndrome has been described. We present a case of a 66-year-old woman with a history of myelodysplastic syndrome who developed histiocytoid Sweet's syndrome. We also review the literature and characterize patients with myelodysplastic syndrome who have developed histiocytoid Sweet's syndrome.

Behçet's: A Disease or a Syndrome? Answer from an Expression Profiling Study

Behçet's disease (BD) is a chronic, relapsing, multisystemic inflammatory disorder with unanswered questions regarding its etiology/pathogenesis and classification. Distinct manifestation based subsets, pronounced geographical variations in expression, and discrepant immunological abnormalities raised the question whether Behçet's is "a disease or a syndrome". To answer the preceding question we aimed to display and compare the molecular mechanisms underlying distinct subsets of BD. For this purpose, the expression data of the gene expression profiling and association study on BD by Xavier et al (2013) was retrieved from GEO database and reanalysed by gene expression data analysis/visualization and bioinformatics enrichment tools. There were 15 BD patients (B) and 14 controls (C). Three subsets of BD patients were generated: MB (isolated mucocutaneous manifestations, n = 7), OB (ocular involvement, n = 4), and VB (large vein thrombosis, n = 4). Class comparison analyses yielded the following numbers of differentially expressed genes (DEGs); B vs C: 4, MB vs C: 5, OB vs C: 151, VB vs C: 274, MB vs OB: 215, MB vs VB: 760, OB vs VB: 984. Venn diagram analysis showed that there were no common DEGs in the intersection "MB vs C" ∩ "OB vs C" ∩ "VB vs C". Cluster analyses successfully clustered distinct expressions of BD. During gene ontology term enrichment analyses, categories with relevance to IL-8 production (MB vs C) and immune response to microorganisms (OB vs C) were differentially enriched. Distinct subsets of BD display distinct expression profiles and different disease associated pathways. Based on these clear discrepancies, the designation as "Behçet's syndrome" (BS) should be encouraged and future research should take into consideration the immunogenetic heterogeneity of BS subsets. Four gene groups, namely, negative regulators of inflammation (CD69, CLEC12A, CLEC12B, TNFAIP3), neutrophil granule proteins (LTF, OLFM4, AZU1, MMP8, DEFA4, CAMP), antigen processing and presentation proteins (CTSS, ERAP1), and regulators of immune response (LGALS2, BCL10, ITCH, CEACAM8, CD36, IL8, CCL4, EREG, NFKBIZ, CCR2, CD180, KLRC4, NFAT5) appear to be instrumental in BS immunopathogenesis.

Sweet's syndrome complicating ulcerative colitis: a rare association

Sweet's syndrome (SS) is a neutrophilic dermatosis disorder of unknown aetiology, characterised by acute fever, neutrophilia, painful erythematous papules, nodules and plaques, and an infiltrate consisting predominantly of mature neutrophils in the upper dermis. Classical SS is a rare extra-intestinal manifestation of inflammatory bowel disease (IBD). It is more common in Crohn's disease than in ulcerative colitis (UC). There is a predilection for women, and for patients with colonic disease and active IBD. We report the case of a 39-year-old woman with a flare of moderate severity UC treated with mesalazine who presented with a 5-day history of acute fever, painful papules and plaques on forearms and legs, episcleritis and cervical pain. Skin biopsies showed papillary dermis inflammatory cell infiltration composed mainly of neutrophils, without evidence of leukocytoclastic vasculitis or panniculitis, compatible with SS. The patient had an excellent response to systemic corticosteroids. Symptoms promptly improved and skin lesions resolved after 7 weeks.

Vitamin D Signaling Modulators in Cancer Therapy

The antiproliferative and pro-apoptotic effects of 1α,25-dihydroxycholecalciferol (1,25(OH)2D3, 1,25D3, calcitriol) have been demonstrated in various tumor model systems in vitro and in vivo. However, limited antitumor effects of 1,25D3 have been observed in clinical trials. This may be attributed to a variety of factors including overexpression of the primary 1,25D3 degrading enzyme, CYP24A1, in tumors, which would lead to rapid local inactivation of 1,25D3. An alternative strategy for improving the antitumor activity of 1,25D3 involves the combination with a selective CYP24A1 inhibitor. The validity of this approach is supported by numerous preclinical investigations, which demonstrate that CYP24A1 inhibitors suppress 1,25D3 catabolism in tumor cells and increase the effects of 1,25D3 on gene expression and cell growth. Studies are now required to determine whether selective CYP24A1 inhibitors+1,25D3 can be used safely and effectively in patients. CYP24A1 inhibitors plus 1,25D3 can cause dose-limiting toxicity of vitamin D (hypercalcemia) in some patients. Dexamethasone significantly reduces 1,25D3-mediated hypercalcemia and enhances the antitumor activity of 1,25D3, increases VDR-ligand binding, and increases VDR protein expression. Efforts to dissect the mechanisms responsible for CYP24A1 overexpression and combinational effect of 1,25D3/dexamethasone in tumors are underway. Understanding the cross talk between vitamin D receptor (VDR) and glucocorticoid receptor (GR) signaling axes is of crucial importance to the design of new therapies that include 1,25D3 and dexamethasone. Insights gained from these studies are expected to yield novel strategies to improve the efficacy of 1,25D3 treatment.

Acral vesicles and bullae in a patient with severe rheumatoid arthritis

We present the case of a 56-year-old black woman with rheumatoid arthritis who developed worsening fatigue, fever, weight loss, and a vesiculobullous skin eruption while being treated with certolizumab pegol for her arthritis. Microscopic findings confirmed the diagnosis of a neutrophilic dermatosis.

C-type lectin domain family 12, member A: A common denominator in Behçet's syndrome and acute gouty arthritis

C-type lectin domain family 12, member A (CLEC12A) is a C-type lectin-like pattern recognition receptor capable of recognizing monosodium urate crystals. Monosodium urate crystals, the causative agents of gout are also among the danger-associated molecular patterns reflecting cellular injury/cell death. In response to monosodium urate crystals, CLEC12A effectively inhibits granulocyte and monocyte/macrophage functions and hence acts as a negative regulator of inflammation. Behçet's syndrome and gout are autoinflammatory disorders sharing certain pathological (neutrophilic inflammation), clinical (exaggerated response to monosodium urate crystals) and therapeutic (colchicine) features. We propose the hypothesis that decreased expression of CLEC12A is a common denominator in the hyperinflammatory responses observed in Behçet's syndrome and gout. Major lines of evidence supporting this hypothesis are: (1) Downregulation/deficiency of CLEC12A is associated with hyperinflammatory responses. (2) CLEC12A polymorphisms with functional and clinical implications have been documented in other inflammatory diseases. (3) Colchicine, a fundamental therapeutic agent used both in Behçet's syndrome and gout is shown to oppose the downregulation of CLEC12A. (4) Behçet's syndrome and gout are characterized by a hyperinflammatory response to monosodium urate crystals and other than gout, Behçet's syndrome is the only inflammatory condition exhibiting this exaggerated response. (5) Genomewide linkage and association studies of Behçet's syndrome collectively point to 12p12-13, the chromosomal region harboring CLEC12A. (6) Patients with severe forms of Behçet's syndrome underexpress CLEC12A with respect to patients with mild forms of the disease. If supported by well-designed, rigorous experiments, the forementioned hypothesis pertinent to CLEC12A will carry important implications for therapy, designing experimental models, and uncovering immunopathogenic mechanisms in Behçet's syndrome and gout.