[Diagnostic and therapy of lupus nephritis - 2023]

The manuscript summarizes the consensus of the Austrian Society of Nephrology on the diagnosis and therapy of lupusnephritis, which is built on existing studies and literature. We discuss in detail the immunosuppressive treatment in proliferative forms of lupusnephritis (III and IV ± V) and in pure lupusnephritis V with nephrotic-range proteinuria. Furthermore, the supportive medication in lupusnephritis is summarized in the consensus. The figures were designed to provide the reader a guidance through the therapeutical approach in lupusnephritis for the daily practice.

Myocardial infarction with non-obstructive coronary arteries in a patient double-seropositive for anti-glomerular basement membrane and anti-neutrophil cytoplasmic antibodies: A case report

We report a case of a patient double-seropositive for anti-glomerular basement membrane (anti-GBM) and anti-neutrophil cytoplasmic antibodies (ANCA) who reported retrosternal chest pain during a regular hemodialysis session associated with ST-segment depression in electrocardiogram and an increase of serum high-sensitivity troponin T. Urgent coronary angiography excluded obstructive coronary artery disease, suggesting the diagnosis of ischemia with non-obstructive coronary arteries. This case illustrates an unusual presentation of cardiovascular involvement in a patient with double-positive ANCA/anti-GBM disease, emphasizing the possible relevance of coronary microvascular dysfunction and the need for close cardiovascular follow-up in this patient population.

Host and microbiome features of secondary infections in lethal covid-19

Secondary infections contribute significantly to covid-19 mortality but driving factors remain poorly understood. Autopsies of 20 covid-19 cases and 14 controls from the first pandemic wave complemented with microbial cultivation and RNA-seq from lung tissues enabled description of major organ pathologies and specification of secondary infections. Lethal covid-19 segregated into two main death causes with either dominant diffuse alveolar damage (DAD) or secondary pneumonias. The lung microbiome in covid-19 showed a reduced biodiversity and increased prototypical bacterial and fungal pathogens in cases of secondary pneumonias. RNA-seq distinctly mirrored death causes and stratified DAD cases into subgroups with differing cellular compositions identifying myeloid cells, macrophages and complement C1q as strong separating factors suggesting a pathophysiological link. Together with a prominent induction of inhibitory immune-checkpoints our study highlights profound alterations of the lung immunity in covid-19 wherein a reduced antimicrobial defense likely drives development of secondary infections on top of SARS-CoV-2 infection.

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Covid-19 autopsy cohort complemented with microbial cultivation and deep sequencing

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Major death causes stratify into DAD and secondary pneumonias

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Prototypical bacterial and fungal agents are found in secondary pneumonias

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Macrophages and C1q stratify DAD subgroups and indicate immune impairment in lungs

MO223: Contribution of Interstitial CD138 + Plasma Cells on the Renal Outcome in Patients with Anca-Associated Vasculitis

BACKGROUND AND AIMS

Plasma cells (PC) are the most differentiated antibody and cytokine-producing B lineage cells and are thought to contribute to the perpetuation of inflammation in patients with ANCA-associated vasculitis (AAV). Agents targeting PCs are of interest in AAV, however, little is known about the role of interstitial CD138 + PCs in these patients. In this study, we aim to demonstrate the impact of this cell population in the prediction of renal outcomes in patients with AAV.

METHOD

Forty AAV patients with glomerulonephritis, diagnosed between 2014 and 2018 at the Division of Nephrology of the Medical University of Graz were included and followed for 36 months. Histological assessments using the kidney allograft Banff classification were performed to describe the tubulointerstitial (TI) damages. Immunohistochemistry analysis was performed in 29 patients to assess the renal interstitial CD138 + cell expression. More than ten CD138 + cells per high power field were stated as high expression (excluding CD138 staining of renal tubular epithelial cells). Changes in kidney function, the incidence of renal relapses (RR), and end-stage renal disease (ESRD) were analyzed.

RESULTS

In the kidney biopsies, N = 21 (72%) patients had a high expression of CD138 + plasma cells. No significant difference was observed in PR3 and MPO serotypes in the group of patients with high CD138 + cell expression (43% versus 57%, P = .793). In addition, no significant difference was seen in the changes in kidney function and the incidence of RR or ESRD between the groups with high and low expression of CD138 + cells during the follow-up period. However, patients with more severe TI damage had more severe proteinuria {urinary albumin/creatinine ratio: 51 [interquartile range (IQR) 42–123] versus 360 (IQR 202–1112) mg/g Creatinine; P = .016} at 3-year follow-up, and tended to have a higher rate of RR and ESRD [i0/i1: N = 2/18 (11%) versus i2/i3: N = 6/22 (27%), P = .258 and i0/i1: N = 2/18 (11%) versus i2/i3: N = 6/22 (27%), P = .258, respectively].

CONCLUSION

Our data indicate a significant proportion of CD138 + PCs in kidney specimens of patients with AAV. Despite the lack of association between this cell population and our cohort’s renal outcome, these results provide additional insights on the renal B-cell clusters in patients with AAV. In addition, our findings go along with already existing data on the association between extended TI damage and worse renal outcome.

Membranous nephropathy associated with immunoglobulin G4-related disease successfully treated with obinutuzumab

Immunoglobulin G4 (IgG4)-releated disease is typically associated with interstitial nephritis, but rare cases of idiopathic membranous nephropathy as a renal manifestation have been described. Obinutuzumab was successfully used in refractory membranous nephropathy, but evidence for the treatment of IgG4-related disease with obinutuzumab is lacking. We report one patient's case with membranous nephropathy associated with IgG4-related disease who was treated with obinutuzumab following an anaphylactic reaction to rituximab. Obinutuzumab treatment resulted in a sustained complete remission of membranous nephropathy and a decrease of IgG4 to the normal range. This case demonstrates that membranous nephropathy associated with IgG4-related disease can be treated successfully with obinutuzumab.

The conundrum of postpartum thrombotic Microangiopathy: case report and considerations for management

Background

Microangiopathic hemolytic anemias and thrombocytopenias in pregnant or postpartum women constitute an interdisciplinary diagnostic and therapeutic challenge in the evaluation of thrombotic microangiopathies (TMA), where urgent care must be considered.

Case presentation

We here report the case of a 21-year-old Somali woman, who was delivered by emergency caesarean section at 35 weeks of gestational age with acute dyspnea, placental abruption and gross edema due to severe preeclampsia/HELLP syndrome. After delivery, she developed acute kidney failure and thrombotic microangiopathy as revealed by kidney biopsy. The lack of early response to plasma exchange prompted extensive laboratory workup. Ultimately, the patient completely recovered with negative fluid balance and control of severe hypertension.

Conclusions

This case report emphasizes the importance to differentiate between primary TMA syndromes and microangiopathic hemolytic anemias due to systemic disorders. Delayed recovery from preeclampsia/HELLP syndrome and malignant hypertension can clinically mimic primary TMA syndromes in the postpartum period.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1286-1) contains supplementary material, which is available to authorized users.

Automatic evaluation of tumor budding in immunohistochemically stained colorectal carcinomas and correlation to clinical outcome

Background

Tumor budding, meaning a detachment of tumor cells at the invasion front of colorectal carcinoma (CRC) into single cells or clusters (<=5 tumor cells), has been shown to correlate to an inferior clinical outcome by several independent studies. Therefore, it has been discussed as a complementary prognostic factor to the TNM staging system, and it is already included in national guidelines as an additional prognostic parameter. However, its application by manual evaluation in routine pathology is hampered due to the use of several slightly different assessment systems, a time-consuming manual counting process and a high inter-observer variability. Hence, we established and validated an automatic image processing approach to reliably quantify tumor budding in immunohistochemically (IHC) stained sections of CRC samples.

Methods

This approach combines classical segmentation methods (like morphological operations) and machine learning techniques (k-means and hierarchical clustering, convolutional neural networks) to reliably detect tumor buds in colorectal carcinoma samples immunohistochemically stained for pan-cytokeratin. As a possible application, we tested it on whole-slide images as well as on tissue microarrays (TMA) from a clinically well-annotated CRC cohort.

Results

Our automatic tumor budding evaluation tool detected the absolute number of tumor buds per image with a very good correlation to the manually segmented ground truth (R2 value of 0.86).

Furthermore the automatic evaluation of whole-slide images from 20 CRC-patients, we found that neither the detected number of tumor buds at the invasion front nor the number in hotspots was associated with the nodal status. However, the number of spatial clusters of tumor buds (budding hotspots) significantly correlated to the nodal status (p-value = 0.003 for N0 vs. N1/N2). TMAs were not feasible for tumor budding evaluation, as the spatial relationship of tumor buds (especially hotspots) was not preserved.

Conclusions

Automatic image processing is a feasible and valid assessment tool for tumor budding in CRC on whole-slide images. Interestingly, only the spatial clustering of the tumor buds in hotspots (and especially the number of hotspots) and not the absolute number of tumor buds showed a clinically relevant correlation with patient outcome in our data.

Electronic supplementary material

The online version of this article (10.1186/s13000-018-0739-3) contains supplementary material, which is available to authorized users.

Lysyl oxidase-like protein 2 (LOXL2) modulates barrier function in cholangiocytes in cholestasis

BACKGROUND & AIMS

The lysyl oxidase-like protein 2 (LOXL2) promotes stabilization of the extracellular matrix, chemotaxis, cell growth and cell mobility. We aimed to (i) identify stimuli of LOXL2 in cholangiopathies, (ii) characterize the effects of LOXL2 on biliary epithelial cells' (BECs) barrier function, (iii) compare LOXL2 expression in primary sclerosing cholangitis (PSC), primary biliary cholangitis, and disease controls, and (iv) to determine LOXL2 expression and its cellular sources in four mouse models of cholangiopathies.

METHODS

Cultured murine BECs were challenged with well-known triggers of cellular senescence, hypoxia, phospholipid-deficient Abcb4^-/- mouse bile and chenodeoxycholic acid and investigated for LOXL2, SNAIL1 and E-cadherin expression and transepithelial electrical resistance with and without LOX-inhibition. In vivo, LOXL2 expression was studied in PSC livers, and controls and mouse models. We compared LOXL2 serum levels in patients with PSC, secondary SC, primary biliary cholangitis, and controls.

RESULTS

Cellular senescence, hypoxia, Abcb4^-/- bile and chenodeoxycholic acid induced LOXL2 and SNAIL1 expression, repressed E-cadherin expression, and significantly reduced transepithelial electrical resistance in BECs. Notably, all of the pathological changes could be recovered via pharmacological LOX-inhibition. Mouse models showed induced LOXL2 expression in the portal region and in association with ductular reaction. LOXL2 serum levels were significantly elevated in patients with cholangiopathies. In PSC, LOXL2 expression was located to characteristic periductal onion skin-type fibrosis, ductular reaction, Kupffer cells, and fibrotic septa. Importantly, in PSC, LOXL2 overexpression was paralleled by E-cadherin loss in BECs from medium-sized bile ducts.

CONCLUSIONS

Reactive BECs produce LOXL2, resulting in increased tight junction permeability, which can be ameliorated by pharmacological LOX-inhibition in vitro. Reactive BECs, portal myofibroblasts, and Kupffer cells are the main sources of LOXL2 in cholangiopathies.

LAY SUMMARY

In this study, we investigate the role of lysyl oxidase-like protein 2 (LOXL2), an enzyme pivotal in the development of organ fibrosis, in the pathogenesis of cholangiopathies (diseases of bile ducts), such as primary sclerosing cholangitis. We found LOXL2 to be expressed in association with bile duct epithelial injury and uncovered mechanisms for its upregulation and the subsequent effects in vitro and in vivo. Our findings support testing of anti-LOXL2 treatment strategies for patients with primary sclerosing cholangitis.

Genetic loss of the muscarinic M3 receptor markedly alters bile formation and cholestatic liver injury in mice

AIM

Hepatic innervation represents a potentially underestimated regulator of liver function and regeneration. The muscarinic 3 receptor (M₃ -R) is the primary cholangiocyte receptor for the afferent parasympathetic innervation of bile ducts. We aimed to determine the specific role of the M₃ -R in bile formation and models for cholestatic liver disease in mice.

METHODS

We compared bile flow and composition in M₃ -R knock-out mice (M₃ -R^-/- ) and wild type littermates (WT). Furthermore, we compared liver inury of M₃ -R^-/- and WT mice after 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding, a well-characterized preclinical model of cholestatic liver disease. To analyze the possible role of the M₃ -R as a therapeutic target, we treated 4-week-old Mdr2^-/- mice, a preclinical model for sclerosing cholangitis, with the M₃ -R agonist bethanechol for 4 weeks.

RESULTS

M₃ -R^-/- mice showed significantly reduced bile flow compared to WT mice, most likely due to decreased biliary HCO₃^- secretion. However, even aged M₃ -R^-/- mice did not spontaneously develop liver injury or cholestasis. Challenging M₃ -R^-/- and WT littermates with DDC feeding showed substantially aggravated liver injury in M₃ -R^-/- mice. After 4 weeks bethanechol treatment, Mdr2^-/- mice showed less liver injury compared to controls.

CONCLUSION

Our experimental findings suggest that M₃ -R-signalling significantly influences bile formation. Loss of the M₃ -R increases susceptibility to cholestatic injury in DDC-fed mice. Since treatment of Mdr2^-/- mice with a M₃ -R agonist decreases liver injury, M3-R signaling may represent a therapeutic target in specific cholangiopathies.

Downgrading of a G3 Neuroendocrine Tumor to a G2 Tumor: Can First-Line Cytotoxic Chemotherapy Change the Tumor Biology?

The antiproliferative treatment options for neuroendocrine tumors (NET)/neuroendocrine carcinomas of the gastrointestinal tract critically depend on the proliferation rate, evaluated by immunohistochemical staining for Ki-67. According to their grading, tumors are treated with somatostatin analogs, mTOR inhibitors, or cytotoxic substances. This case illustrates downgrading of a primarily highly proliferative NET achieved by a variation of cytotoxic chemotherapy regimens, followed by a combination therapy using everolimus together with lanreotide. The latter medication might lead to a good clinical response as far as tumor growth is concerned.

The role of natural killer T cells in a mouse model with spontaneous bile duct inflammation

Natural killer T (NKT) cells are activated by lipid antigens presented by CD1d molecules and represent a major lymphocyte subset of the liver. NODc3c4 mice spontaneously develop biliary inflammation in extra- and intrahepatic bile ducts. We demonstrated by flow cytometry that invariant NKT (iNKT) cells were more abundant in the thymus, spleen, and liver of NODc3c4 mice compared to NOD mice. iNKT cells in NODc3c4 mice displayed an activated phenotype. Further, NOD and NODCd1d^-/- mice were irradiated and injected with NODc3c4 bone marrow, and injection of NODc3c4 bone marrow resulted in biliary infiltrates independently of CD1d expression in recipient mice. Activation or blocking of NKT cells with α-galactosylceramide or anti-CD1d antibody injections did not affect the biliary phenotype of NODc3c4 mice. NODc3c4.Cd1d^-/- mice were generated by crossing NODCd1d^-/- mice onto a NODc3c4 background. NODc3c4.Cd1d^-/- and NODc3c4 mice developed the same extent of biliary disease. This study demonstrates that iNKT cells are more abundant and activated in the NODc3c4 model. The portal inflammation of NODc3c4 mice can be transferred to irradiated recipients, which suggests an immune-driven disease. Our findings imply that NKT cells can potentially participate in the biliary inflammation, but are not the primary drivers of disease in NODc3c4 mice.

NorUrsodeoxycholic acid ameliorates cholemic nephropathy in bile duct ligated mice

BACKGROUND & AIMS

Severe cholestasis may cause cholemic nephropathy that can be modeled in common bile duct ligated (CBDL) mice. We aimed to explore the therapeutic efficacy and mechanisms of norursodeoxycholic acid (norUDCA) in cholemic nephropathy.

METHODS

In 8-week CBDL mice fed with norUDCA (prior or post CBDL) or chow we evaluated serum urea levels, urine cytology and urinary neutrophil gelatinase associated lipocalin (uNGAL), kidney and liver tissue quantification of fibrosis by hydroxyproline content and gene chip expression looking at key genes of inflammation and fibrosis. Moreover, we comprehensively analysed bile acid profiles in liver, kidney, serum and urine samples.

RESULTS

NorUDCA-fed CBDL mice had significantly lower serum urea and uNGAL levels and less severe cholemic nephropathy as demonstrated by normal urine cytology, significantly reduced tubulointerstitial nephritis, and renal fibrosis as compared to controls. NorUDCA underwent extensive metabolism to produce even more hydrophilic compounds that were significantly enriched in kidneys.

CONCLUSION

NorUDCA ameliorates cholemic nephropathy due to the formation of highly hydrophilic metabolites enriched in kidney. Consequently, norUDCA may represent a medical treatment for cholemic nephropathy.

LAY SUMMARY

The term cholemic nephropathy describes renal dysfunction together with characteristic morphological alterations of the kidney in obstructive cholestasis that can be mimicked by ligation of the common bile duct in mice. Feeding the hydrophilic bile acid norUDCA to bile duct ligated mice leads to a significant amelioration of the renal phenotype due to the formation of highly hydrophilic metabolites enriched in the kidney and may therefore represent a medical treatment for cholemic nephropathy.

[Pathology of the R1 classification in visceral cancer surgery]

The completeness of tumor removal is described in the residual tumor classification (R classification). The R category of a surgical specimen reflects the effects of treatment, influences further treatment decisions and is associated with patient survival. Thorough pathological examination of all resection planes, including the circumferential margin, is necessary for accurate classification.

Anal verrucous carcinoma is not related to infection with human papillomaviruses and should be distinguished from giant condyloma (Buschke-Löwenstein tumour)

AIMS

Verrucous carcinoma (VC) is a variant of well-differentiated squamous cell carcinoma and in the anal region is regarded as synonymous with giant condyloma (Buschke-Löwenstein tumour) (BLT). Aetiology, diagnostic criteria and clinical behaviour of both lesions are controversial. Recent studies suggest that VC at other sites is not associated with human papillomaviruses (HPV). We hypothesized that anal VC is also not related to HPV, while BLT is a HPV-induced lesion.

METHODS AND RESULTS

Ten cases of VC and four cases of BLT were included. Several techniques were used for HPV detection: in-situ hybridization for HPV6, 11, 16 and 18, six different polymerase chain reaction (PCR) protocols for detection of at least 89 HPV types from alpha-, beta-, gamma- and mu-PV genera and in-situ hybridization for high-risk HPV E6/E7 mRNA; p16 immunohistochemistry and morphometric analysis were also performed. Alpha-, gamma- and mu-PVs were not found in any case of VC, while HPV6 was detected in all cases of BLT. p16 overexpression was not present in any of the lesions. Among microscopic features, only the absence of koilocytosis and enlarged spinous cells seem to be useful to distinguish VC from BLT.

CONCLUSIONS

Our results suggest that anal VC, similarly to VC at other sites, is not associated with HPV infection, and must be distinguished from BLT, which is associated with low-risk HPV. Only with well-set diagnostic criteria will it be possible to ascertain clinical behaviour and optimal treatment for both lesions.

MUC1, MUC2, MUC5AC, and MUC6 in colorectal cancer: expression profiles and clinical significance

Mucin glycoprotein expression can be altered during the carcinogenic process. The impact on the prognosis of patients with colorectal cancer (CRC) is controversial. We analyzed tumors from 381 patients for MUC1, MUC2, MUC5AC, and MUC6 expression by immunohistochemical staining, using tissue microarrays. Progression-free and cancer-specific survival were determined using the Kaplan-Meier method. Expression of intestinal mucin MUC2 was lost in 85 (23 %) CRCs, and patients with MUC6-negative tumors showed shorter progression-free survival (PFS, p = 0.043). Gastric mucins MUC5AC and MUC6 showed high (>50 %) aberrant expression in 28 (8 %) and 9 (2 %) cases, respectively. High expression of MUC5AC was associated with longer PFS (p = 0.055). High expression of MUC6 was associated with 100 % PFS (p = 0.024) and longer cancer-specific survival (CSS, p = 0.043). MUC1 was expressed in 238 (64 %) tumors and had no impact on outcome. When analysis was restricted to stages II and III, loss of MUC2 was associated with adverse outcome. Overexpression of both MUC5AC and MUC6 significantly predicted favorable PFS and CSS. In conclusion, loss of MUC2 expression proved to be a predictor of adverse outcome, while the gain of aberrant expression of MUC5AC and particularly of MUC6 was associated with favorable outcome in CRC, notably in intermediate stages II and III.

Inclusion of cytological features in tumor grading improves prognostic stratification of patients with colorectal cancer

PURPOSE

Tumor grade is a traditional prognostic parameter in colorectal cancer. Remarkably, however, there is still no generally accepted consensus how to perform tumor grading. In this study, we systematically compared the prognostic value of traditional grading based upon histological features, that is, gland formation alone with grading based upon both histological and cytological features, such as nuclear pleomorphism and anaplasia ("alternative grade").

METHODS

Three hundred eighty-one tumors of randomly selected patients were retrospectively reviewed. Traditional and alternative tumor grades were related to various clinicopathological features and to progression-free and cancer-specific survival applying both univariate and multivariate testing.

RESULTS

Traditional and alternative tumor grades were significantly associated with T and N classification, tumor size, lymphovascular invasion, as well as both progression-free and cancer-specific survival. In Cox's proportional hazards regression models, the alternative grade was superior to the traditional tumor grade and was significantly associated with progression-free survival (hazard ratio 1.57, 95% confidence interval 1.04-2.35; p = 0.031), independent of patients' age and gender, T and N classification, and lymphovascular invasion. Likewise, patients with tumors with high alternative grade were more likely to die of disease (hazard ratio 1.30, 95% confidence interval 0.85-2.00), but this difference was not statistically significant (p = 0.22).

CONCLUSIONS

Tumor grade based upon both histological and cytological features was superior to grade based upon histological features alone and proved to be an independent prognostic parameter. Thus, tumor grade based upon both histological and cytological features may help to improve prognostic stratification and may thereby affect clinical decision-making and patient management.

Loss of keratin 19 favours the development of cholestatic liver disease through decreased ductular reaction

Keratins (K) are cytoprotective proteins and keratin mutations predispose to the development of multiple human diseases. K19 represents the most widely used marker of biliary and hepatic progenitor cells as well as a marker of ductular reaction that constitutes the basic regenerative response to chronic liver injury. In the present study, we investigated the role of K19 in biliary and hepatic progenitor cells and its importance for ductular reaction. K19 wild-type (WT) and knockout (KO) mice were fed: (a) 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC); (b) cholic acid (CA); (c) a choline-deficient, ethionine-supplemented (CDE) diet; or (d) were subjected to common bile duct ligation (CBDL). The bile composition, liver damage, bile duct proliferation, oval cell content and biliary fibrosis were analysed. In untreated animals, loss of K19 led to redistribution of the K network in biliary epithelial cells (BECs) but to no obvious biliary phenotype. After DDC feeding, K19 KO mice exhibited (compared to WTs): (a) increased cholestasis; (b) less pronounced ductular reaction with reduced ductular proliferation and fewer oval cells; (c) impaired Notch 2 signalling in BECs; (d) lower biliary fibrosis score and biliary bicarbonate concentration. An attenuated oval cell proliferation in K19 KOs was also found after feeding with the CDE diet. K19 KOs subjected to CBDL displayed lower BEC proliferation, oval cell content and less prominent Notch 2 signal. K19 deficiency did not change the extent of CA- or CBDL-induced liver injury and fibrosis. Our results demonstrate that K19 plays an important role in the ductular reaction and might be of importance in multiple chronic liver disorders that frequently display a ductular reaction.

Grading lymph node metastasis: a feasible approach for prognostication of patients with stage III colorectal cancer

This study aimed to assess the clinicopathological significance of tumour differentiation of metastatic lymph node tissue in patients with American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) stage III colorectal cancer. In a cohort of 145 patients, lymph node grades were G1 in 77 (53.1%), G2 in 41 (28.3%) and G3 in 27 (18.6%) cases, respectively. Despite differences in 77 (53.1%) cases, primary tumour and lymph node grade correlated significantly (Somer's D=0.639; p<0.001). Lymph node grade was significantly associated with N classification (p=0.009), tumour size (p=0.024) and lymphovascular invasion (p=0.004). Patients with lymph node grade G1 had better progression-free survival (p=0.031) and cancer-specific survival (p=0.008). Multivariable analysis identified lymph node grade as independent predictor of cancer-specific survival in this cohort. In conclusion, lymph node grade emerged as a promising novel prognostic variable for patients with AJCC/UICC stage III disease. Additional studies are warranted to validate this new finding.

Vitamin D modulates biliary fibrosis in ABCB4-deficient mice

Purpose

Impaired vitamin D receptor signaling represents an aggravating factor during liver injury, and recent studies suggest that vitamin D might exert a protective role in chronic hepatobiliary diseases. We hypothesized that vitamin D supplementation would ameliorate liver fibrosis in ATP-binding cassette transporter B4 knockout (Abcb4^−/−) mice as a preclinical model of sclerosing cholangitis.

Methods

Abcb4^−/− and wild-type mice were fed a regular chow diet (600 IU vitamin D/kg food) or diets with lower (100 IU/kg) and higher (2,400 IU/kg) vitamin D concentrations for 12 weeks. Serum 25-hydroxyvitamin D concentrations were measured by chemiluminescence immunoassays. Liver injury and biliary fibrosis were assessed by liver enzyme activities, histopathology and hepatic collagen contents. Hepatic mRNA expression of markers for fibrosis, vitamin D and bile acid metabolism were analyzed by quantitative PCR.

Results

Different vitamin D concentrations were observed depending on genotype and diet group, with Abcb4^−/− mice on the control diet showing lower vitamin D concentrations compared to wild-type mice. Abcb4^−/− animals on the low vitamin D diet demonstrated the most advanced liver fibrosis and highest hepatic collagen contents. Feeding Abcb4^−/− mice a high vitamin D diet enriched serum vitamin D levels, lowered liver enzyme activities, altered expression levels of profibrogenic genes and ameliorated, in part, liver injury.

Conclusions

This is the first report to demonstrate that fibrogenesis in the established Abcb4^−/− model is influenced by vitamin D supplementation. Since vitamin D modulates sclerosing cholangitis in vivo, we speculate that sufficient vitamin D intake might improve liver damage and induce antifibrotic effects in chronic cholestasis in humans.

Electronic supplementary material

The online version of this article (doi:10.1007/s12072-014-9548-2) contains supplementary material, which is available to authorized users.

Characterization of animal models for primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a chronic cholangiopathy characterized by biliary fibrosis, development of cholestasis and end stage liver disease, high risk of malignancy, and frequent need for liver transplantation. The poor understanding of its pathogenesis is also reflected in the lack of effective medical treatment. Well-characterized animal models are utterly needed to develop novel pathogenetic concepts and study new treatment strategies. Currently there is no consensus on how to evaluate and characterize potential PSC models, which makes direct comparison of experimental results and effective exchange of study material between research groups difficult. The International Primary Sclerosing Cholangitis Study Group (IPSCSG) has therefore summarized these key issues in a position paper proposing standard requirements for the study of animal models of PSC.

Bile acids trigger cholemic nephropathy in common bile-duct-ligated mice

Tubular epithelial injury represents an underestimated but important cause of renal dysfunction in patients with cholestasis and advanced liver disease, but the underlying mechanisms are unclear. To address the hypothesis that accumulation and excessive alternative urinary elimination of potentially toxic bile acids (BAs) may contribute to kidney injury in cholestasis, we established a mouse model for detailed in vivo time course as well as treatment studies. Three-day common bile duct ligation (CBDL) induced renal tubular epithelial injury predominantly at the level of aquaporin 2-positive collecting ducts with tubular epithelial and basement membrane defects. This was followed by progressive interstitial nephritis and tubulointerstitial renal fibrosis in 3-, 6-, and 8-week CBDL mice. Farnesoid X receptor knockout mice (with a hydrophilic BA pool) were completely protected from CBDL-induced renal fibrosis. Prefeeding of hydrophilic norursodeoxycholic acid inhibited renal tubular epithelial injury in CBDL mice. In addition, we provide evidence for renal tubular injury in cholestatic patients with cholemic nephropathy.

CONCLUSION

We characterized a novel in vivo model for cholemic nephropathy, which offers new perspectives to study the complex pathophysiology of this condition. Our findings suggest that urinary-excreted toxic BAs represent a pivotal trigger for renal tubular epithelial injury leading to cholemic nephropathy in CBDL mice.

Chronic cholestatic liver diseases: clues from histopathology for pathogenesis

Chronic cholestatic liver diseases include fibrosing cholangiopathies such as primary biliary cirrhosis or primary sclerosing cholangitis. These and related cholangiopathies clearly display pathologies associated with (auto)immunologic processes. As the cholangiocyte's apical membrane is exposed to the toxic actions of the bile fluid, the interaction of bile with cholangiocytes and the biliary tree in general must be considered to completely understand the pathogenesis of cholangiopathies. While the molecular processes involved in the hepatocellular formation of bile are well understood in both normal and pathophysiologic conditions, those in the bile ducts of normal liver and in livers with cholangiopathies lag behind. This survey highlights key mechanisms known to date that are important for the formation of bile by hepatocytes and its modification by the biliary tree. It also delineates the clinical pathophysiologic findings for cholangiopathies and puts them in perspective with current experimental models to reveal the pathogenesis of cholangiopathies and develop novel therapeutic approaches.

Differential effects of norUDCA and UDCA in obstructive cholestasis in mice

BACKGROUND & AIMS

The quest for effective drugs to treat cholangiopathies led to the development of norUDCA previously shown to have potent choleretic effects and to heal cholangiopathy in Abcb4 knockout (Abcb4(-/-)) mice. Its mother compound UDCA had detrimental effects in common bile duct ligated (CBDL) mice, presumably related to its choleretic effects. norUDCA choleretic effects may therefore raise safety concerns when used in cholangiopathies with biliary obstruction. We therefore aimed at comparing the effects of UDCA and norUDCA in clear-cut obstructive cholestasis.

METHODS

0.5% UDCA- or norUDCA-fed wild type and Abcb4(-/-) mice were subjected to CBDL or selective bile duct ligation (SBDL) and compared to controls with regard to liver injury. Bile flow, bile composition, and biliary manometry were compared in UDCA-fed, norUDCA-fed and control mice. Toxicity of UDCA and norUDCA was compared in vitro.

RESULTS

Compared to UDCA, liver injury in CBDL mice was significantly lower in almost all norUDCA groups. In SBDL mice, only UDCA induced bile infarcts in the ligated lobes, whereas norUDCA even ameliorated liver injury. In vitro, UDCA induced cellular ATP depletion and was significantly more toxic than norUDCA in HepG2 cells, mouse bile duct epithelial cells, and primary human hepatocytes.

CONCLUSIONS

Compared to norUDCA, UDCA is significantly more toxic in CBDL mice. norUDCA, in contrast to UDCA, significantly ameliorates liver injury in SBDL mice. Our findings uncover profound differences in metabolism and therapeutic mechanisms of both bile acids with important clinical consequences.

Absence of adipose triglyceride lipase protects from hepatic endoplasmic reticulum stress in mice

Nonalcoholic fatty liver disease (NAFLD) is characterized by triglyceride (TG) accumulation and endoplasmic reticulum (ER) stress. Because fatty acids (FAs) may trigger ER stress, we hypothesized that the absence of adipose triglyceride lipase (ATGL/PNPLA2)-the main enzyme for intracellular lipolysis, releasing FAs, and closest homolog to adiponutrin (PNPLA3) recently implicated in the pathogenesis of NAFLD-protects against hepatic ER stress. Wild-type (WT) and ATGL knockout (KO) mice were challenged with tunicamycin (TM) to induce ER stress. Serum biochemistry, hepatic TG and FA profiles, liver histology, and gene expression for markers of hepatic lipid metabolism, ER stress, and inflammation were explored. Moreover, cell-culture experiments were performed in Hepa1.6 cells after the knockdown of ATGL before FA and TM treatment. TM increased hepatic TG accumulation in ATGL KO, but not in WT, mice. Lipogenesis and β-oxidation were repressed at the gene-expression level (sterol regulatory element-binding transcription factor 1c, fatty acid synthase, acetyl coenzyme A carboxylase 2, and carnitine palmitoyltransferase 1 alpha) in both WT and ATGL KO mice. Genes for very-low-density lipoprotein (VLDL) synthesis (microsomal triglyceride transfer protein and apolipoprotein B) were down-regulated by TM in WT and even more in ATGL KO mice, which displayed strongly reduced serum VLDL cholesterol levels. Notably, ER stress markers glucose-regulated protein, C/EBP homolog protein, spliced X-box-binding protein, endoplasmic-reticulum-localized DnaJ homolog 4, and inflammatory markers Tnfα and iNos were induced exclusively in TM-treated WT, but not ATGL KO, mice. Total hepatic FA profiling revealed a higher palmitic acid/oleic acid (PA/OA) ratio in WT mice, compared to ATGL KO mice, at baseline. Phosphoinositide-3-kinase inhibitor-known to be involved in FA-derived ER stress and blocked by OA-was increased in TM-treated WT mice only. In line with this, in vitro OA protected hepatocytes from TM-induced ER stress.

CONCLUSIONS

Lack of ATGL may protect from hepatic ER stress through alterations in FA composition. ATGL could constitute a new therapeutic strategy to target ER stress in NAFLD.

Tumor budding is an independent predictor of outcome in AJCC/UICC stage II colorectal cancer

BACKGROUND

In colorectal cancer, the morphology of the invasive tumor margin may reflect aggressiveness of tumor growth, thus providing important prognostic information. The tumor growth pattern according to Jass and the extent of tumor budding were analyzed in patients with American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) stage II disease.

METHODS

Tumors of 120 randomly selected patients with AJCC/UICC stage II disease were retrospectively reviewed for tumor growth pattern (expanding vs. infiltrating) and the extent of tumor budding, with high-grade budding reflecting presence of 10 or more budding foci scattered at the invasive tumor margin. Progression-free and cancer-specific survivals were determined by the Kaplan-Meier method. For multivariable analysis, Cox's proportional hazards regression models were performed.

RESULTS

The infiltrating growth pattern was significantly associated with histological subtype and lymphovascular invasion, while high-grade budding was significantly associated with tumor grade and lymphovascular invasion. High-grade budding, but not the infiltrating growth pattern, was significantly associated with outcome in univariable analysis. Cox's proportional hazards regression models proved tumor budding to be an independent predictor of disease progression (hazard ratio 3.91, 95 % confidence interval 1.3-11.77; P = 0.02) and cancer-related death (hazard ratio 5.90, 95 % confidence interval 1.62-21.51; P = 0.007). The combination of infiltrating growth pattern and high-grade budding did not have a stronger prognostic significance than tumor budding alone.

CONCLUSIONS

Tumor budding independently predicted patient outcome in patients with AJCC/UICC stage II colorectal cancer and may therefore be used for accurate prognostication, patient counseling, and design of clinical trials by using integrated multimodal therapy.

Is there a rationale to record lymphatic invasion in node-positive colorectal cancer?

This study aimed to evaluate the prognostic significance of lymphatic invasion in colorectal cancers that have already spread to regional lymph nodes. 168 patients with node-positive tumours (colon, n=98; rectum, n=70) were retrospectively evaluated. Lymphatic invasion was assessed on H&E stained slides and univariable and multivariable analyses were applied. Lymphatic invasion was detected in 95 (57%) cases and was significantly associated with tumour and node classification and tumour differentiation. Patients with tumours showing lymphatic invasion had decreased progression-free survival (p=0.025) and cancer-specific survival (p=0.082). Stratified by location, lymphatic invasion was significantly associated with decreased progression-free (p=0.010) and cancer-specific (p=0.023) survival in colon cancers, yet not in rectal cancers. Multivariable analysis proved T4 (HR 2.18, 95% CI 1.40 to 3.39; p<0.001) and N2 (HR 1.68, 95% CI 1.07 to 2.66; p=0.03) as independent predictors of progression-free survival and T4 (HR 1.90, 95% CI 1.17 to 3.07; p=0.009), N2 (HR 2.27, 95% CI 1.38 to 3.73; p=0.001) and poor tumour differentiation (HR 2.18, 95% CI 1.39 to 3.43; p<0.001) as independent predictors of cancer-specific survival, while for lymphatic invasion no influence on outcome was noted. In conclusion, only tumour and node classification, and tumour differentiation proved to be independent prognostic variables in node-positive colorectal cancer and merit special attention in clinical decision-making.

Keratin 20 - a diagnostic and prognostic marker in colorectal cancer?

Colorectal cancer cells characteristically show strong expression of keratin 20 (K20) and lack expression of keratin 7 (K7). The biological significance of reduced K20 expression, however, is unclear. 381 colorectal cancers with 148 corresponding metastases were evaluated for K20 and K7 expression by immunohistochemistry using a tissue microarray technique. K20 immunoreactivity was assessed semiquantitatively as either negative, low (<50% of cancer cells) or high (≥50% of cancer cells). Progression-free and cancer-specific survivals were determined using the Kaplan-Meier method. Expression of K20 was observed in 348 out of 372 (94%) evaluable primary tumors, with 135 (36%) cases showing low K20 and 213 (57%) cases high K20 expression, while 24 (6%) tumors completely lacked K20 immunoreactivity. Reduced K20 expression (lack of staining or low expression) was significantly associated with poor differentiation, large tumor size and mismatch repair deficiency, but did not significantly affect patients' outcome. Immunoreactivity of K20 and K7 in metastatic tissues matched well with that of corresponding primary tumors, with high concordance for lymph node (p<0.001) and distant metastases (p<0.001), respectively. In conclusion, our data illustrate the value of keratin subtyping in carcinoma of unknown primary (CUP) syndrome: K20 expression is common in colorectal cancer and the K20 high / K7 negative immunoprofile represents the predominant phenotype. Reduced K20 expression may, however, lead to false-negative assessment of metastatic deposits if only small amounts of tissue are obtained (e.g. in needle biopsies), particularly in poorly differentiated cancers. Reduced expression of K20 may be used to select tumors for microsatellite instability testing.

Mucinous differentiation in colorectal cancer--indicator of poor prognosis?

AIMS

  To analyse the prognostic impact of mucinous differentiation in colorectal mucinous adenocarcinomas and adenocarcinomas with a mucinous component.

METHODS AND RESULTS

  A total of 381 tumours were reviewed for mucinous differentiation by two independent pathologists. Mismatch repair status was assessed by immunohistochemistry. Prognostic significance was assessed by univariate and multivariate analyses. Eighty-one (21%) tumours were Union Internationale Contre le Cancer (UICC) Stage I, 120 (31%) Stage II, 126 (33%) Stage III and 54 (14%) Stage IV. Mucinous adenocarcinomas accounted for 12% and adenocarcinomas with a mucinous component for 19% of tumours. Mucinous differentiation was associated significantly with mismatch repair protein deficiency. The presence of extracellular mucin, regardless of extent, did not affect patients' outcome, while tumour grade, vascular and perineural invasion, tumour border configuration and budding were associated significantly with outcome. Cox analysis proved venous invasion to be an independent predictor of outcome in mucinous adenocarcinomas and both venous invasion and tumour budding as independent predictors of outcome in adenocarcinomas with any amount of mucin.

CONCLUSIONS

  Mucinous adenocarcinomas and/or adenocarcinomas with mucinous component do not differ from conventional adenocarcinomas with respect to prognosis and histological predictors of outcome. Hence, recording of mucinous differentiation may be used as an indicator of mismatch repair deficiency, but not for prognostic stratification.

Keratin 7 expression in colorectal cancer--freak of nature or significant finding?

AIMS

 To assess the prevalence of keratin 7 (K7) expression in colorectal cancer and to correlate findings with clinicopathological parameters and patients' outcome.

METHOD AND RESULTS

A total of 370 patients were evaluated for K7 expression by immunohistochemistry using a tissue microarray technique. K7 expression was scored semiquantitatively as either focal (<10%), moderate (10-50%) or extensive (>50%). In all, 32 (9%) tumours were immunoreactive for K7, with five cases showing extensive, four moderate and 23 focal expression, respectively. K7 expression was associated with poor tumour differentiation (P = 0.005) and the extent of tumour budding (P = 0.02). In whole sections, K7 immunoreactivity prevailed in single cells and small clusters of cells at the invasion front. Analysis of serial sections showed that K7-positive cells colocalized with keratin 20, whereas they lacked immunoreactivity for E-cadherin, MUC2 and MIB-1. Disease progression occurred in 52% of patients with K7-positive tumours and 41% with K7-negative tumours (P = 0.19); 48% of patients with K7-positive tumours but only 33% with K7-negative tumours died of disease (P = 0.06).

CONCLUSIONS

Aberrant expression of K7 in budding cancer cells represents a modification of the epithelial phenotype ('epithelial-epithelial transition': EET) which may be linked to gains in motility and invasive potential.

Pathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) represents a chronic cholestatic liver disease with fibroobliterative sclerosis of intra- and/or extrahepatic bile ducts, eventually leading to biliary cirrhosis. The association with human leukocyte antigen (HLA) and non-HLA haplotypes and the presence of autoantibodies in sera of PSC patients support a crucial role for immune-mediated mechanisms in the initiation and progression of PSC. The strong clinical association between PSC and inflammatory bowel diseases led to intriguing pathogenetic concepts, in which the inflamed gut with translocation of bacterial products and homing of gut-primed memory T lymphocytes via aberrantly expressed adhesion molecules plays a fundamental role. Genetically or chemically modified bile composition was shown to induce sclerosing cholangitis and liver fibrosis in a number of animal models ("toxic bile concept"). The potential role of vascular injury with ischemia of bile duct epithelium cells in the development of sclerosing cholangitis is supported by animal models of endothelial cell injury showing close morphological similarities with human PSC.

Will we ever model PSC? - "it's hard to be a PSC model!"

Cholangiopathies such as primary sclerosing cholangitis (PSC) represent an important group of liver diseases of the intra- and extrahepatic bile ducts frequently causing end-stage liver disease with significant morbidity and mortality due to limited treatment options. The relatively low incidence of PSC and the difficult accessibility of the human bile duct system for longitudinal studies may represent some of the critical reasons for the lack of profound knowledge in regard to PSC pathophysiology. Therefore, there is an urgent need for reliable, well-defined and easily reproducible animal models to learn more about the pathophysiology of PSC and to test novel treatment modalities. In an ideal world, immunogenetically predisposed animals would develop fibrous-obliterative cholangitis of the intra- and extrahepatic bile ducts in association with inflammation of the gut (especially colitis) in a highly reproducible manner allowing to test new drugs. To date, however, no such animal model is available. We aimed to provide a systematic overview of current available rodent models for sclerosing cholangitis and biliary fibrosis and therefore critically analyzed the characteristics of models for chemically-induced cholangitis, knock-out mouse models with cholangitis, cholangitis induced by infectious agents, models of experimental biliary obstruction, models involving enteric bacterial cell-wall components or colitis, and models of primary biliary epithelial and endothelial cell injury.

Intramural and extramural vascular invasion in colorectal cancer: prognostic significance and quality of pathology reporting

BACKGROUND

Blood vessel invasion has been associated with poor outcome in colorectal cancer (CRC), whereas the prognostic impact of lymphatic invasion is less clear. The authors of this report evaluated venous and lymphatic invasion as potential prognostic indicators in patients with CRC focusing on lymph node-negative patients and compared routine and review pathology diagnoses.

METHODS

In total, 381 tumors from randomly selected patients were retrospectively reviewed. The presence of vascular invasion was related to disease-free and cancer-specific survival using the Kaplan-Meier method. For multivariable analysis, Cox proportional hazards regression models were performed.

RESULTS

Lymphatic invasion and venous invasion were observed in 126 patients (33%) and 87 patients (23%), respectively, and were associated significantly with tumor classification, lymph node status, American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) disease stage, tumor differentiation, pattern of invasion, and extent of tumor budding. The detection of vascular invasion was related to the number of examined tissue blocks. Venous and lymphatic invasion proved to be significant prognostic variables in univariable and multivariable analyses. Extramural vascular involvement was of particular significance. When the analysis was restricted to patients with (AJCC/UICC) stage II disease, venous invasion, but not lymphatic invasion, was identified as an independent prognostic variable. Review pathology diagnoses differed significantly from routine diagnoses with respect to prognostic impact.

CONCLUSIONS

Venous and lymphatic invasion proved to be significant prognostic variables in patients with CRC. The detection of vascular invasion and, consequently, risk stratification of affected patients were related to the quality of pathology workup, ie, the number of examined tissue blocks. Observed differences between review and routine pathology diagnoses illustrated the need for high-quality pathology reporting and also for standardized quality control.

Gastric cancer and concomitant renal cancer: a systematic immunohistochemical and molecular analysis

The frequency of gastric cancer in patients with renal cell carcinoma (RCC) is exceptionally high in our region suggesting a common molecular basis. Our study aimed to characterize tumors and to analyze possible underlying molecular features in 12 patients with gastric cancer and concomitant RCC. We performed an immunohistochemical analysis including p53 protein expression, proliferative activity (MIB-1), mismatch repair status (hMLH1, hMSH2, hMSH6, PMS2) and E-cadherin expression in gastric cancers, which were additionally analyzed for Epstein-Barr-Encoded-RNA (EBER) by in situ hybridization. Microsatellite instability was analyzed with a PCR multiplex system and capillary electrophoresis. KRAS mutations in codons 12 and 13 were tested by pyrosequencing. All patients had clear cell RCCs, 10 of which were well differentiated and diagnosed in an early stage, while the gastric cancers of these patients were generally poorly or undifferentiated and diagnosed in an advanced stage. Gastric cancers showed reduced E‑cadherin staining in 10 out of 12 cases. Two gastric cancers demonstrated loss of hMLH1 and PMS2, which was confirmed by molecular analysis showing a high degree of microsatellite instability. All RCCs were microsatellite stable. KRAS mutation was detected in one of the two instable gastric cancers, while none of the RCCs had KRAS mutations. Another gastric cancer was positive for EBV. In conclusion, a coherent cause for gastric cancer and concomitant RCC, such as Lynch syndrome, a prominent role of KRAS mutation or EBV infection, was not found in our series. Other factors leading to a higher susceptibility for cancer must be explored to explain why individuals with RCC have a higher risk of developing gastric cancer in our region.

Clinical significance of pT sub-classification in surgical pathology of colorectal cancer

PURPOSE

Tumour stage is the strongest prognostic parameter in colorectal cancer. The study aimed to evaluate the prognostic impact of pT2, pT3, and pT4 sub-classification.

METHODS

Three hundred eighty-one surgical colorectal cancer specimens were retrospectively re-evaluated. pT2 tumours were sub-classified according to infiltration of the inner circumferential (pT2a) or outer longitudinal (pT2b) layer of the muscularis propria. pT3 tumours were sub-classified by measuring the maximal tumour invasion beyond the outer border of the muscularis propria (pT3a <or= 1 mm, pT3b > 1-5 mm, pT3c > 5-15 mm, and pT3d > 15 mm). pT4 tumours were sub-classified according to invasion of other organs or structures (pT4a) or perforation of the visceral peritoneum (pT4b). Data were correlated with other pathological parameters and patient outcome.

RESULTS

Seventy pT2 tumours were re-classified as 37 pT2a and 33 pT2b tumours. There was no significant association with tumour grade, angioinvasion, or lymph node involvement and no significant impact on prognosis. Two hundred eighteen pT3 tumours were re-classified as 49 pT3a, 83 pT3b, 53 pT3c, and 33 pT3d tumours. pT3 sub-classification was significantly associated with tumour grade, angioinvasion, and lymph node involvement and proved to be an independent prognostic variable with respect to progression-free and cancer-specific survival. A cut-off level of 5 mm is recommended. Sixty-five pT4 tumours were re-classified as 15 pT4a and 50 pT4b tumours. There was no significant association with tumour grade, angioinvasion, or lymph node involvement and no significant impact on prognosis.

CONCLUSIONS

pT3 sub-classification was significantly associated with patient outcome. In contrast, pT2 and pT4 sub-classification did not show clinical significance.

Ileocecal intussusception caused by lung cancer metastasis

Intussusception is a rare clinical finding in adults. Most cases occur in the distal small bowel or large intestine. We report the case of a 65-year-old woman with known non-small-cell lung cancer (NSCLC) who presented with acute abdomen and ileus-like symptoms. Abdominal computed tomography suggested ileocecal intussusception. The patient underwent right hemicolectomy and the histopathological workup showed ileal NSCLC metastasis as the lead lesion of intussusception. The classic triad of cramping abdominal pain, bloody diarrhea and a palpable tender mass, which is present in the majority of pediatric patients, is only infrequently observed in adults. Thus, symptoms are often nonspecific and the clinical presentation may be inconspicuous. Because of the large proportion of structural anomalies, adult intussusception requires definitive treatment, of which surgical resection is the treatment of choice. In patients with colocolonic or ileocolonic intussusception, malignancy should be considered and therefore en bloc resection rather than reduction is the recommended surgical technique, whereas cases of enteric intussusceptions may be reduced by limited resection of the small intestine.

Merkel cell carcinoma metastasizing to the kidney mimicking primary neuroendocrine renal cancer

A 56-year-old male with a history of cutaneous neuroendocrine (Merkel cell) carcinoma presented with a solid mass of the left kidney, measuring 10 cm in largest diameter. On histology, the tumour was composed of loosely packed uniform cells with round-to-oval nuclei and scant cytoplasm. Immunohistochemically, the tumour cells diffusely expressed pancytokeratin and neuroendocrine markers, such as chromogranin A, synaptophysin and CD56 (NCAM). Distinct paranuclear dot-like expression of cytokeratin 20 showed the lesion to be metastatic Merkel cell carcinoma. This is the first reported case of Merkel cell carcinoma metastatic to the kidney mimicking primary neuroendocrine renal cancer. We discuss the differential diagnosis of the tumour and perform a systematic literature review, including potential indications for renal tumour biopsy in patients with a history of nonrenal malignancy.