Successful pharmacological intervention at different levels of the complement system in an in vitro complement fixation model for bullous pemphigoid.

Bullous pemphigoid (BP) is characterized by deposition of immunoglobulins and complement along the epidermal basement membrane (BM). In humans, there is a lack of functional studies targeting the complement system (CS). This study investigates activation of all complement pathways in BP skin biopsies. Moreover, pharmacological inhibition at different levels of the CS was investigated using anti-complement compounds in a complement fixation BP assay. In this retrospective study, 21 frozen biopsies from BP patients were stained by direct immunofluorescence for C1q, MBL, ficolin-2, C4d, properdin, C3c and C5b-9. Sera from 10 patients were analysed in a complement fixation assay in the presence of C1 inhibitor, anti-factor B monoclonal antibody (mAb), anti-C3 mAb and anti-C5 mAb and compared with dexamethasone. The two readouts were the quantity of complement deposited along the BM and the release of sC5b-9 in the supernatant. Our results show classical and alternative complement pathway activation in BP skin biopsies, but could not demonstrate significant lectin pathway activation. In contrast to dexamethasone, complement deposition along the BM could be selectively inhibited by anti-C1 and anti- factor B. More downstream, selective intervention at the level of C3 and C5 could effectively reduce complement deposition along the BM and the release of sC5b-9 in the supernatant. This study shows that selective intervention in either the classical, alternative or terminal pathway prevented deposition of complement along the BM in an in vitro BP model. The results of our study greatly encourage the clinical development of complement inhibitors for the treatment of BP.

Reflectance confocal microscopy as a non-invasive imaging tool in vulvar high-grade squamous intraepithelial lesions and lichen sclerosus: A descriptive morphological study in patients and healthy volunteers.

Incorrect and delayed diagnosis of vulvar high-grade squamous intraepithelial neoplasia (vHSIL) and lichen sclerosus (LS) increases malignant progression risks and negatively impacts prognosis and quality of life. There is a need to improve diagnosis and monitoring. Reflectance confocal microscopy is a non-invasive imaging tool that visualizes skin structures at cellular resolution. The objectives were to explore feasibility and patient acceptability of vulvar RCM imaging and to identify RCM characteristics that are discriminative for vulvar HSIL and LS. This was a prospective, cross-sectional, observational clinical trial in patients with vHSIL and LS compared to healthy volunteers. RCM images and vulvar tissue samples were obtained. Five (5) patients with vHSIL, 10 patients with LS and 10 healthy volunteers were enrolled. In total, 100 image series of vulvar skin were obtained, including lesional and nonlesional sites. The RCM technique was considered acceptable for application by patients and healthy controls. Healthy vulvar skin was characterized by a homogenous, normal honeycomb patterned epidermis and a clear epidermal-dermal junctions. Vulvar HSIL and LS displayed an atypical honeycomb pattern of the epidermis and lymphocytic influx with presence of melanophages. Distinct features specifically observed in LS included the presence of hyalinised vessels and sclerotic areas in the dermis. RCM is a non-invasive imaging technique that is feasible and clinically acceptable to apply on vulvar skin, both in patients with premalignant lesions and healthy controls. Recognition and validation of disease-specific characteristics could make reflectance confocal microscopy a clinical tool to non-invasively aid identification of vulvar premalignancies.

A multimodal, comprehensive characterization of a cutaneous wound model in healthy volunteers.

Development of pharmacological interventions for wound treatment is challenging due to both poorly understood wound healing mechanisms and heterogeneous patient populations. A standardized and well-characterized wound healing model in healthy volunteers is needed to aid in-depth pharmacodynamic and efficacy assessments of novel compounds. The current study aims to objectively and comprehensively characterize skin punch biopsy-induced wounds in healthy volunteers with an integrated, multimodal test battery. Eighteen (18) healthy male and female volunteers received three biopsies on the lower back, which were left to heal without intervention. The wound healing process was characterized using a battery of multimodal, non-invasive methods as well as histology and qPCR analysis in re-excised skin punch biopsies. Biophysical and clinical imaging read-outs returned to baseline values in 28 days. Optical coherence tomography detected cutaneous differences throughout the wound healing progression. qPCR analysis showed involvement of proteins, quantified as mRNA fold increase, in one or more healing phases. All modalities used in the study were able to detect differences over time. Using multidimensional data visualization, we were able to create a distinction between wound healing phases. Clinical and histopathological scoring were concordant with non-invasive imaging read-outs. This well-characterized wound healing model in healthy volunteers will be a valuable tool for the standardized testing of novel wound healing treatments.

Hedgehog pathway mutations are involved in the pathogenesis of plaque-type "trichoblastoma": A report of two cases.

We present two cases of plaque-type trichoblastoma with atypical foci. A rare variant of trichoblastoma is the plaque variant, which is characterized by poor circumscription and locally infiltrative growth pattern. These lesions mostly require multiple stages of Mohs micrographic surgery. Debate still exists whether this variant should be considered as a benign entity or as "low-grade" malignant counterpart of trichoblastoma. In this report we describe two cases of plaque-type trichoblastoma with atypical foci, which harbored somatic mutations in the Hedgehog pathway, thus should be acknowledged as intermediate malignancies. In addition, extensive molecular workup of both the trichoblastic and atypical component in sequential lesions in the same patient was performed.

Long-term consequences of juvenile vulvar lichen sclerosus: A cohort study of adults with a histologically confirmed diagnosis in childhood or adolescence.

INTRODUCTION: Vulvar lichen sclerosus (VLS) occurs in at least one in 900 girls. There is limited knowledge as to what extent the disease persists in adulthood and what the repercussions in adulthood may be. The aim of this study is to evaluate the long-term consequences of VLS diagnosed in childhood or adolescence. MATERIAL AND METHODS: The population of females histologically diagnosed with VLS in childhood or adolescence in the Netherlands between 1991 and 2015 was identified through the national pathology database. Histological specimens were retrieved and re-evaluated. Potential participants for whom the diagnosis was reconfirmed and who are now adults, were then traced and surveyed. Descriptive statistics were calculated and compared with the literature. Main outcome measures are the demographics of the cohort, their scores on standardized quality of life (QoL) and sexuality questionnaires and answers to additional questions regarding patients' experience with the disease. The questionnaires used were the Dermatology Life Quality Index (DLQI), the Skindex-29, the Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale-Revised (FSDS-R). Secondary outcome measures include obstetric history and histological features found in the original tissue specimens. RESULTS: A total of 81 women participated, median age 29.0 years, median follow-up from childhood diagnosis 19.5 years. Both QoL and sexuality were somewhat affected in 51.9% of cases. Less than half (45%) reported having regular check-ups. Forty-five (56%) reported symptoms within the past year; of those with symptoms, 14 (31%) were not under surveillance. Cesarean section rate (14.5%) was comparable to the general population, and there were more high-grade obstetric anal sphincter injuries with vaginal deliveries than expected. Sixteen respondents (20%) were not aware of the childhood diagnosis prior to this study. CONCLUSIONS: Symptoms due to VLS are reported by most adults diagnosed as juveniles. QoL and sexuality are affected and correlate to recent symptoms. VLS as a juvenile does not preclude a vaginal delivery. Women diagnosed with VLS in childhood or adolescence are often lost to follow-up.

Cutaneous Lesions of Mastocytosis: Mast Cell Count, Morphology, and Immunomolecular Phenotype.

ABSTRACT: Mastocytosis is a condition characterized by accumulation of clonal mast cells (MCs) that often involves the skin. Pathologists are often challenged with skin biopsies with a question of cutaneous lesions of mastocytosis (CLM) including cutaneous mastocytosis, mastocytosis in the skin, or systemic mastocytosis. The histopathological criteria for CLM remain poorly defined due to heterogeneity of the published literature and the lack of comparative prospective studies. MC count is greatly influenced by detection and counting techniques, criteria for viable MCs used, anatomical location biopsied, and the dermal level that is analyzed. Although MC numbers in CLM can be significantly higher compared with healthy controls and a patient with other inflammatory skin diseases, in some instances, considerable overlap exists. Based on the largest studies published, it is suggested that a number of MCs between 75 and 250 MCs/mm 2 are a range in which CLM should be considered and, above 250 MC/mm 2 , a diagnosis of CLM can be made. A recent study showed a high specificity of >95% of a MC count >139 MC/mm 2 compared with patients with other inflammatory skin diseases. Noteworthy, the total number and percentage of MCs is significantly higher in children compared with adults, particularly in polymorphic maculopapular cutaneous mastocytosis. In difficult cases, ancillary techniques such as D816V mutation analysis on formalin-fixed paraffin-embedded tissue have a high sensitivity and specificity. There is no enough evidence that immunohistochemistry of CD25, CD2, or CD30 has any additional value in the diagnosis, subtyping, or clinical course of mastocytosis.

Dermatoscopy and Optical Coherence Tomography in Vulvar High-Grade Squamous Intraepithelial Lesions and Lichen Sclerosus: A Prospective Observational Trial.

OBJECTIVE: This study aimed to examine potential discriminatory characteristics of dermatoscopy and dynamic optical coherence tomography (D-OCT) on vulvar high-grade squamous intraepithelial lesions (vHSIL) and lichen sclerosus (LS) compared with healthy vulvar skin. METHODS: A prospective observational clinical trial was performed in 10 healthy volunteers, 5 vHSIL and 10 LS patients. Noninvasive imaging measurements using dermatoscopy and D-OCT were obtained at several time points, including lesional and nonlesional vulvar skin. Morphologic features of vHSIL and LS were compared with healthy controls. Epidermal thickness and blood flow were determined using D-OCT. Patients reported tolerability of each study procedure, including reference vulvar biopsies. The main outcome measures were feasibility and tolerability of imaging modalities, dermatoscopy and OCT characteristics, OCT epidermal thickness and D-OCT dermal blood flow. RESULTS: The application of dermatoscopy and D-OCT is feasible and tolerable. In vHSIL, dermatoscopic warty structures were present. In LS, sclerotic areas and arborizing vessels were observed. Structural OCT in the vulvar area aligned with histology for hyperkeratosis and dermal-epidermal junction visualization. Currently, the OCT algorithm is unable to calculate the epidermal thickness of the uneven vulvar area. Dynamic optical coherence tomography showed statistically significant increased blood flow in LS patients (mean ± SD, 0.053 ± 0.029) to healthy controls (0.040 ± 0.012; p = .0024). CONCLUSIONS: The application of dermatoscopy and D-OCT is feasible and tolerable in vHSIL and LS patients. Using dermatoscopy and D-OCT, the authors describe potential characteristics to aid differentiation of diseased from healthy vulvar skin, which could complement clinical assessments.

An interleukin 6-based genetic risk score strengthened with interleukin 10 polymorphisms associated with long-term kidney allograft outcomes.

Of all kidney transplants, half are still lost in the first decade after transplantation. Here, using genetics, we probed whether interleukin 6 (IL-6) could be a target in kidney transplantation to improve graft survival. Additionally, we investigated if a genetic risk score (GRS) based on IL6 and IL10 variants could improve prognostication of graft loss. In a prospective cohort study, DNA of 1271 donor-recipient kidney transplant pairs was analyzed for the presence of IL6, IL6R, IL10, IL10RA, and IL10RB variants. These polymorphisms and their GRS were then associated with 15-year death-censored allograft survival. The C|C-genotype of the IL6 polymorphism in donor kidneys and the combined C|C-genotype in donor-recipient pairs were both associated with a reduced risk of graft loss (p = .043 and p = .042, respectively). Additionally, the GRS based on IL6, IL6R, IL10, IL10RA, and IL10RB variants was independently associated with the risk of graft loss (HR 1.53, 95%-CI [1.32-1.84]; p < .001). Notably, the GRS improved risk stratification and prediction of graft loss beyond the level of contemporary clinical markers. Our findings reveal the merits of a polygenic IL-6-based risk score strengthened with IL-10- polymorphisms for the prognostication and risk stratification of late graft failure in kidney transplantation.

Intradermal lipopolysaccharide challenge as an acute in vivo inflammatory model in healthy volunteers.

AIMS: Whereas intravenous administration of Toll-like receptor 4 ligand lipopolysaccharide (LPS) to human volunteers is frequently used in clinical pharmacology studies, systemic use of LPS has practical limitations. We aimed to characterize the intradermal LPS response in healthy volunteers, and as such qualify the method as local inflammation model for clinical pharmacology studies. METHODS: Eighteen healthy male volunteers received 2 or 4 intradermal 5 ng LPS injections and 1 saline injection on the forearms. The LPS response was evaluated by noninvasive (perfusion, skin temperature and erythema) and invasive assessments (cellular and cytokine responses) in skin biopsy and blister exudate. RESULTS: LPS elicited a visible response and returned to baseline at 48 hours. Erythema, perfusion and temperature were statistically significant (P < .0001) over a 24-hour time course compared to saline. The protein response was dominated by an acute interleukin (IL)-6, IL-8 and tumour necrosis factor response followed by IL-1ß, IL-10 and interferon-γ. The cellular response consisted of an acute neutrophil influx followed by different monocyte subsets and dendritic cells. DISCUSSION: Intradermal LPS administration in humans causes an acute, localized and transient inflammatory reaction that is well-tolerated by healthy volunteers. This may be a valuable inflammation model for evaluating the pharmacological activity of anti-inflammatory investigational compounds in proof of pharmacology studies.

Histopathological characteristics are instrumental to distinguish monomorphic from polymorphic maculopapular cutaneous mastocytosis in children.

BACKGROUND: Mastocytosis is characterized by the accumulation of mast cells (MCs) in the skin or other organs, and can manifest at any age. A significant number of paediatric mastocytosis cases persist after puberty. In particular, monomorphic maculopapular cutaneous mastocytosis (mMPCM) is often persistent and associated with systemic mastocytosis. However, clinical differentiation of MPCM from polymorphic (p)MPCM can be difficult. AIM: To identify histopathological features that can help to distinguish mMPCM from other subtypes of paediatric mastocytosis. METHODS: This was a retrospective study using skin biopsies from patients with any subtype of mastocytosis. The localization and density of the MC infiltrate, MC morphology and expression of aberrant markers were evaluated and correlated with clinical characteristics. RESULTS: In total, 33 biopsies were available for evaluation from 26 children [(10 with mMPCM, 5 with mastocytoma, 3 with diffuse cutaneous mastocytosis (DCM), 8 with pMPCM)] and 7 adults with MPCM. The MC number was increased in all patients, but was higher in children than adults (P < 0.01). The presence of mMPCM was associated with sparing of the papillary dermis from MC infiltration, whereas MC density in the papillary dermis was highest in pMPCM and DCM (P < 0.01). The positive predictive value of the presence of a reticular MC infiltrate for mMPCM was 72.7% (95% CI 51.4-87.0), and the negative predictive value was 83.3% (95% CI 42.2-97.2). There were no relevant differences in the expression of CD2, CD25 or CD30 between the different subtypes. CONCLUSION: Skin histopathology might enhance the phenotypical differentiation of mMPCM from other subtypes in children, thereby increasing the accuracy of one's prognosis.

Trichoblastic carcinosarcoma with panfollicular differentiation (panfollicular carcinosarcoma) and CTNNB1 (beta-catenin) mutation.

We present a case of trichoblastic carcinosarcoma with panfollicular differentiation. An 80-year-old man presented with a lesion on the left ear, which had been present for several months. Histopathology revealed a well-demarcated neoplasm in the dermis composed of intimately intermingled malignant epithelial and mesenchymal cells. The epithelial component showed multilineage follicular differentiation toward all of the elements of a normal hair follicle. Molecular analysis revealed identical molecular aberrations in both epithelial and mesenchymal components including CTNNB1 and SUFU mutations. To the best of our knowledge, this is the first report of panfollicular carcinosarcoma and of the presence of a CTNNB1 mutation in trichoblastic carcinosarcoma.

Diagnostic Utility of C4d by Direct Immunofluorescence in Bullous Pemphigoid.

ABSTRACT: Bullous pemphigoid (BP) is an autoimmune blistering disease that commonly affects elderly patients. Direct immunofluorescence (DIF) for immunoglobulin G (IgG) and C3c on frozen skin biopsies is the gold standard for the diagnosis of BP. In a minority of cases, IgG and/or C3c are found negative, and in these situations, there is a need for a more stable diagnostic marker of BP. C4d is biologically inactive, but has a long half-life, rendering it a long-lived marker for antibody-mediated complement activation. Previous studies already demonstrated that C4d was diagnostically useful in formalin-fixed paraffin-embedded skin biopsies of patients with BP. We hypothesized that C4d detected by DIF could also be a promising diagnostic marker for BP, particularly in IgG and/or C3c DIF-negative cases. In this single-center retrospective study, 69 cases of BP were analyzed for linear deposition of C4d; of the 69 cases, n = 26 were IgG+/C3c-, n = 10 IgG+/C3c+, and n = 33 IgG-/C3c-. Results were compared with n = 39 negative controls. Seven of the 26 (27%) IgG+/C3c- and 3 of the 33 (9%) IgG-/C3c- BP cases were positive for C4d. All 10 IgG+/C3c+ cases were also C4d positive. In the negative control group, 2 of the 39 (5%) were found positive for C4d. In conclusion, the current study shows that C4d is a more sensitive but not a 100% specific marker of BP. We conclude that C4d by DIF could be an interesting diagnostic adjunct for BP, particularly in IgG-/C3c- double negative cases.

Dermal C4d Deposition and Neutrophil Alignment Along the Dermal-Epidermal Junction as a Diagnostic Adjunct for Hypocomplementemic Urticarial Vasculitis (Anti-C1q Vasculitis) and Underlying Systemic Disease.

Urticarial vasculitis (UV) is a clinicopathologic entity characterized by persistent urticarial lesions with biopsy features of vasculitis. Currently, only certain clinical features such as arthralgia and serum complement concentrations are used to identify UV patients at risk for an underlying systemic disease. Hypocomplementemic urticarial vasculitis (HUV) is in contrast to normocomplementemic urticarial vasculitis (NUV), strongly associated with underlying systemic disease, especially systemic lupus erythematosus (SLE). The aim of this study was to find specific histopathological features associated with HUV and underlying systemic disease in UV. In addition, the use of complement C4d deposition in skin biopsies was evaluated as a diagnostic adjunct for HUV- and UV-associated systemic disease. In this retrospective study, the clinical, histopathological, and immunohistological (C4d) features of 43 patients with UV were compared between HUV and NUV and analyzed for association with UV-associated systemic disease. Eight of 43 patients with UV (19%) had hypocomplementemia. Patients with HUV showed a significantly higher number of perivascular neutrophils and lower number of eosinophils compared to NUV. Of all histopathological features, alignment of neutrophils along the dermal-epidermal junction (DEJ) and dermal granular C4d deposition were found to be strongly associated with HUV and underlying SLE. This study shows that both the alignment of neutrophils along the DEJ and dermal C4d deposition are strongly associated with HUV and SLE. Therefore, these (immuno)histopathological features can be used as an easy diagnostic adjunct for early detection of underlying systemic disease in UV.

Genome-Wide Association Scan of Serum Urea in European Populations Identifies Two Novel Loci.

BACKGROUND: Serum urea level is a heritable trait, commonly used as a diagnostic marker for kidney function. Genome-wide association studies (GWAS) in East-Asian populations identified a number of genetic loci related to serum urea, however there is a paucity of data for European populations. METHODS: We performed a two-stage meta-analysis of GWASs on serum urea in 13,312 participants, with independent replication in 7,379 participants of European ancestry. RESULTS: We identified 6 genome-wide significant single nucleotide polymorphisms (SNPs) in or near 6 loci, of which 2 were novel (POU2AF1 and ADAMTS9-AS2). Replication of East-Asian and Scottish data provided evidence for an additional 8 loci. SNPs tag regions previously associated with anthropometric traits, serum magnesium, and urinary albumin-to-creatinine ratio, as well as expression quantitative trait loci for genes preferentially expressed in kidney and gastro-intestinal tissues. CONCLUSIONS: Our findings provide insights into the genetic underpinnings of urea metabolism, with potential relevance to kidney function.

Treatment with intravenous immunoglobulins and methylprednisolone may significantly decrease loss of renal function in chronic-active antibody-mediated rejection.

BACKGROUND: Chronic-active antibody mediated rejection (c-aABMR) is a major contributor to long-term kidney allograft loss. We conducted a retrospective analysis to establish the efficacy of treatment with intravenous immunoglobulins (IVIG) and pulse methylprednisolone (MP) of patients with c-aABMR. METHODS: Sixty-nine patients, in the period 2005-2017, with the diagnosis (suspicious for) c-aABMR that were treated with IVIG and MP were included. Patients were administered three doses of 1 g intravenous MP combined with a single dose of IVIG (1 g/kg body weight). Primary outcome was the decline in allograft function one year post treatment. Responders to IVIG-MP therapy were defined by an eGFR one year after treatment which was at least 25% above the projected allograft function. RESULTS: Patients showed an average decline in eGFR of 9.8 ml/min/1.73m2 the year prior to treatment. Following treatment, a significant reduction (p < 0.001) in eGFR decline was observed (6.3 ml/min/1.73m2). Furthermore, a significant improvement in proteinuria was observed upon treatment (p < 0.001). Sixty-two percent (n = 43) of the patients were considered a responder and showed considerable slowing of graft function deterioration in the year after treatment (p < 0.001). Three and 5-year graft survival was significantly superior in responders. CONCLUSIONS: More than 60% of patients with c-aABMR with a progressive decline in eGFR respond favorably to treatment with IVIG-MP resulting in a significant improvement of graft survival (Sablik, Am J Transplant 18, 2018).

Diagnostic accuracy of immunofluorescence versus immunoperoxidase staining to distinguish immune complex-mediated glomerulonephritis and C3 dominant glomerulopathy.

AIMS: The technique used for classification of membranoproliferative glomerulonephritis (MPGN) has been changed from an electron microscopy-based to an immunofluorescence (IF)-based semiquantitative technique with immunoperoxidase (IP) staining as a backup option when IF is not possible. Since data on that matter is lacking, our aims were to study the interobserver variability, the correlation and the reclassification of MPGN based on these two techniques. METHODS AND RESULTS: We retrospectively analysed cases of type 1 MPGN. We repeated IF staining and performed IP staining for IgG, kappa, lambda, C3c and C4d in 35 renal biopsies, among which 19 biopsies had matched IP and IF samples. We observed substantial to near-perfect agreement among the seven observers for both IF and IP (W coefficients from 0.66 for IF lambda to 0.89 for IF C4d). Of the 19 cases with matched IP and IF samples, five (26%) turned out to have different diagnoses on IF and on IP. Also, the ability of C4d to discriminate immune complex-mediated glomerulonephritis (ICGN) from C3 glomerulopathy (C3G) was poor, with areas under the curve of 0.44 [95% confidence interval (CI) 0.24-0.63] and 0.66 (95% CI 0.50-0.81) for the receiver operating characteristic curves of IF and IP respectively. Limitations include the fact that no clinical data regarding complement activation were available. CONCLUSION: The diagnosis of ICGN versus C3GN depends on the immunochemical technique used. Also, the use of C4d failed to discriminate ICGN from C3G in our study. Further validation studies are required to avoid misdiagnosis based on kidney biopsy.

Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia-reperfusion injury.

The complement system, and specifically C5a, is involved in renal ischemia-reperfusion (IR) injury. The 2 receptors for complement anaphylatoxin C5a (C5aR1 and C5aR2) are expressed on leukocytes as well as on renal epithelium. Extensive evidence shows that C5aR1 inhibition protects kidneys from IR injury; however, the role of C5aR2 in IR injury is less clear as initial studies proposed the hypothesis that C5aR2 functions as a decoy receptor. By Using wild-type, C5aR1-/-, and C5aR2-/- mice in a model of renal IR injury, we found that a deficiency of either of these receptors protected mice from renal IR injury. Surprisingly, C5aR2-/- mice were most protected and had lower creatinine levels and reduced acute tubular necrosis. Next, an in vivo migration study demonstrated that leukocyte chemotaxis was unaffected in C5aR2-/- mice, whereas neutrophil activation was reduced by C5aR2 deficiency. To further investigate the contribution of renal cell-expressed C5aR2 vs leukocyte-expressed C5aR2 to renal IR injury, bone marrow chimeras were created. Our data show that both renal cell-expressed C5aR2 and leukocyte-expressed C5aR2 mediate IR-induced renal dysfunction. These studies reveal the importance of C5aR2 in renal IR injury. They further show that C5aR2 is a functional receptor, rather than a decoy receptor, and may provide a new target for intervention.-Poppelaars, F., van Werkhoven, M. B., Kotimaa, J., Veldhuis, Z. J., Ausema, A., Broeren, S. G. M., Damman, J., Hempel, J. C., Leuvenink, H. G. D., Daha, M. R., van Son, W. J., van Kooten, C., van Os, R. P., Hillebrands, J.-L., Seelen, M. A. Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia-reperfusion injury.

Chronic-active antibody-mediated rejection with or without donor-specific antibodies has similar histomorphology and clinical outcome - a retrospective study.

Chronic-active antibody-mediated rejection (c-aABMR) is defined as histological evidence of chronic endothelial injury (cg), also known as transplant glomerulopathy, and either microvascular inflammation (MVI) or positivity for C4d. Importantly, the presence of donor-specific antibodies (DSA) is currently still mandatory for the diagnosis of c-aABMR. This retrospective study of 41 c-aABMR patients investigates whether cases suspicious for c-aABMR (DSA negative, n = 24) differ from cases of c-aABMR (DSA positive, n = 17) with respect to renal histology, allograft function and long-term graft survival. All included patients had progressive loss of allograft function and were diagnosed by for cause biopsy and scored according to the Banff '15 criteria. In all DSApos cases, DSA were de novo and the majority was directed against HLA-II being mostly anti-HLA-DQ antibodies. There were no statistically significant differences in clinical characteristics, decline in allograft function and renal allograft survival in cases with or without DSAs. All cases showed chronic histomorphological damage and inflammation, irrespective of the presence of DSA. Renal histology and clinical outcome of patients suspicious for c-aABMR (DSAneg) do not significantly differ from patients with a diagnosis of c-aABMR (DSApos). We believe that our study adds to the ongoing debate regarding the need for DSAs to be present for the diagnosis of c-aABMR.

Fibrous Papule: A Histopathologic Review.

Fibrous papule (FP) is a common benign lesion located primarily in the nose. Although its histogenesis has been marred with controversies in the past, the dermal dendrocyte is now largely accepted to be the putative cell of origin. Histopathologic diagnosis of an FP is straightforward in most cases, which shows characteristics of an angiofibroma. Several histologic variants have been described, recognition of which is important to avoid a misdiagnosis and inappropriate treatment. This review presents a historical perspective into the histogenesis, discusses the histopathologic features and potential diagnostic pitfalls of classic FP, and lists the various histologic variants and their differential diagnoses.