IgG4-related kidney disease: Clinicopathologic features, differential diagnosis, and mimics.

IgG4-related kidney disease (IgG4-RKD) encompasses all forms of kidney disease that are part of IgG4-related disease (IgG4-RD). First recognized as IgG4-related tubulointerstitial nephritis (IgG4-TIN), and then IgG4-related membranous glomerulonephritis (IgG4-MGN), we now recognize additional patterns of interstitial nephritis, glomerular disease, and vascular disease that can be seen as part of IgG4-RKD. The clinical presentation is variable and can include acute or chronic kidney injury, proteinuria or nephrotic syndrome, mass lesion(s), and obstruction. While usually associated with other organ involvement by IgG4-RD, kidney-alone involvement is present in approximately 20 % of IgG4-RKD. Compared to IgG4-RD overall, patients with IgG4-RKD are more likely to show increased serum IgG4 or IgG, and more likely to have hypocomplementemia. In this review, we extensively cover other types of autoimmune and plasma cell-rich interstitial nephritis, mass forming inflammatory diseases of the kidney, and other mimics of IgG4-TIN, in particular ANCA-associated disease.

An Unexpected Diagnosis Uncovered by Quantitative Molecular Findings: A Case Report.

A 74-year-old male presented with rectal pain; workup uncovered an anal mass, and a diagnosis of melanoma was rendered via histologic examination and immunohistochemical (IHC) studies. Droplet digital PCR (ddPCR)-based BRAF testing was performed and revealed the presence of BRAF V600E, which is a common targetable genetic alteration in melanoma. Interestingly, the ratio of mutant to wild-type copy number was low (0.3%), whereas tumor cell percentage on tissue slides was 90%. With additional workup, BRAF V600E IHC confirmed a very small subset of BRAF V600E-positive cells, and a next-generation sequencing (NGS) panel revealed a pathogenic KIT variant, p.L576P, with an allele frequency of 63%. It was initially hypothesized that the main driver of the melanoma was the KIT alteration, whereas a small subclone (not detected by NGS, which has a 5% limit of detection) was driven by the BRAF V600E detected by ddPCR. To determine whether there were morphologic differences between the 2 clones, a careful review of the histology was performed and revealed distinct morphology of the BRAF V600E-positive cells, including pale cytoplasm, nuclear grooves, and infiltrating eosinophils. Additional IHC workup of the BRAF V600E-positive cells showed coexpression of CD1a, Langerin, and S100, diagnostic of Langerhans cell histiocytosis (LCH). This diagnosis was unexpected and would have been missed without highly sensitive molecular testing; yet it is of clinical importance for the patient. This case raises interesting biology questions regarding the relationship between melanoma and LCH; moreover, it highlights the importance of integrating quantitative information in molecular data interpretation.

Clinical Utility Validation of an Automated Ultrarapid Gene Fusion Assay for NSCLC.

Introduction: Gene rearrangements are frequent oncologic drivers in NSCLC, and many are suitable for treatment with Food and Drug Administration-approved or experimental targeted therapies. We evaluated the accuracy, specimen acceptance profile, and limits of detection of a rapid fusion assay (Idylla GeneFusion Assay), a commercially available ultrarapid molecular assay, for its clinical utility. Methods: A collection of 97 specimens which had previously undergone next-generation sequencing testing were analyzed using the rapid fusion assay. Accuracy was evaluated by sensitivity and specificity compared with the next-generation sequencing results. The performance characteristics were tested by using a variety of different clinically relevant specimen types. Limits of detection were assessed by evaluating different input of tumor percentage and material amount. Results: The rapid fusion assay was found to have 100% sensitivity in detecting fusions of ALK, ROS1, RET, NTRK1, and MET exon 14 skipping and 83% sensitivity for NTRK2/3 fusions. There were 100% specificity in detecting fusions of ROS1, RET, NTRK2/3, and MET exon 14 skipping and 98% specificity for ALK. Testing was successful with formalin-fixed paraffin-embedded biopsy and surgical tissues, cell blocks from fine-needle aspiration and pleural fluid (down to 5% tumor content, 18 mm2 tissue scraped), cytology smears (≥300 cells), and previously extracted RNA (minimal 20 ng). Conclusions: The rapid fusion assay is quick, accurate, and versatile, allowing reliable detection of ALK, ROS1, RET fusions, and MET exon 14 skipping in NSCLC, and NTRK fusions. Rapid molecular testing may expedite treatment with appropriate targeted therapies.

Methylated DNA Markers of Esophageal Squamous Cancer and Dysplasia: An International Study.

BACKGROUND: Discovery of methylated DNA markers (MDM) of esophageal squamous cell carcinoma (ESCC) has sparked interest in assessing these markers in tissue. We evaluated MDMs in ESCC from three geographically and ethnically distinct populations, and explored the feasibility of assaying MDMs from DNA obtained by swallowed balloon devices. METHODS: MDMs were assayed in ESCC and normal tissues obtained from the populations of United States, Iran, and China, and from exfoliative cytology specimens obtained by balloons in a Chinese population. Areas under the receiver operating curve (AUC) of MDMs discriminating ESCC from normal tissues were calculated. Random forest prediction models were built, trained on U.S. cases and controls, and calibrated to U.S.-only controls (model 1) and three-country controls (model 2). Statistical tests were used to assess the relationship between dysplasia and MDM levels in balloons. RESULTS: Extracted DNA from 333 ESCC and 322 normal tissues was analyzed, in addition to archival DNA from 98 balloons. For ESCC, model 1 validated in Iranian and Chinese tissues with AUCs of 0.90 and 0.87, and model 2 yielded AUCs of 0.99, 0.96, and 0.94 in tissues from the United States, Iran, and China, respectively. In Chinese balloons, MDMs showed a statistically significant trend of increasing levels with increasing grades of dysplasia (P < 0.004). CONCLUSIONS: MDMs accurately discriminate ESCC from normal esophagus in tissues obtained from high- and low-incidence countries. Preliminary data suggest that levels of MDMs assayed in DNA from swallowed balloon devices increase with dysplasia grade. Larger studies are needed to validate these results. IMPACT: MDMs coupled with minimally invasive collection methods have the potential for worldwide application in ESCC screening.

De novo pauci-immune glomerulonephritis in renal allografts.

Pauci-immune glomerulonephritis in the native kidney presents with renal insufficiency, proteinuria, and hematuria, and is usually due to anti-neutrophil cytoplasmic antibodies. Rarely, kidney transplants can show this pattern as de novo disease. We performed a retrospective analysis in 10 cases of de novo pauci-immune glomerulonephritis. The mean time from transplant to diagnostic biopsy was 32 months (range, 4-96). All biopsies showed focal necrotizing or crescentic glomerulonephritis (mean 16% glomeruli, range 2-36%). Immunofluorescence and electron microscopy showed a pauci-immune pattern. No patients had evidence of systemic vasculitis. Anti-neutrophil cytoplasmic antibody results were available for 7 patients and were negative in all but one. Most patients had functioning grafts at one year after diagnosis. Two patients had repeat biopsies that showed continued active glomerulonephritis. We report the first clinicopathologic series of de novo pauci-immune glomerulonephritis which appears to be a unique pathologic entity that may occur early or late post-transplant and in our cohort is not associated with systemic vasculitis and usually not associated with anti-neutrophil cytoplasmic antibodies. The degree of crescent formation and renal impairment are milder than those of pauci-immune crescentic glomerulonephritis in the native kidney.

Immunohistochemical and Ultrastructural Features of Hepatocellular Cytoplasmic Globules in Venous Outflow Impairment.

OBJECTIVES: To examine the immunohistochemical and ultrastructural features of hepatocellular cytoplasmic globules in venous outflow impairment (VOI). METHODS: Sixty-four liver core biopsies were screened. Patients with α-1 antitrypsin (AAT) deficiency were excluded. All biopsies were stained with H&E, Masson trichrome, periodic acid-Schiff with diastase digestion (PAS-D), phosphotungstic acid hematoxylin (PTAH), complement protein 4d (C4d) immunostain, and AAT immunostain. Electron microscopy was also performed. RESULTS: Hepatocellular globules were identified in 8% of in-house cases. Causes of VOI included heart failure and Budd-Chiari syndrome. The hepatocellular cytoplasmic globules showed size variability, random distribution, and positivity for PAS-D, PTAH, and AAT. C4d was inconsistently positive. Electron microscopy showed that the globules were lysosome-bound inclusions containing microfibrillar material and fibrinogen. CONCLUSIONS: PAS-D-positive hepatocellular globules occur in VOI. They cross-react with AAT but have different appearance, localization, and ultrastructural composition from globules in AAT deficiency.

New Pharmacological Strategies to Increase cGMP.

The intracellular nucleotide cyclic guanosine monophosphate (cGMP) is found in many human organ tissues. Its concentration increases in response to the activation of receptor enzymes called guanylyl cyclases (GCs). Different ligands bind GCs, generating the second messenger cGMP, which in turn leads to a variety of biological actions. A deficit or dysfunction of this pathway at the cardiac, vascular, and renal levels manifests in cardiovascular diseases such as heart failure, arterial hypertension, and pulmonary arterial hypertension. An impairment of the cGMP pathway also may be involved in the pathogenesis of obesity as well as dementia. Therefore, agents enhancing the generation of cGMP for the treatment of these conditions have been intensively studied. Some have already been approved, and others are currently under investigation. This review discusses the potential of novel drugs directly or indirectly targeting cGMP as well as the progress of research to date.

Microalbuminuria and left ventricular mass in overweight and obese hypertensive patients: role of the metabolic syndrome.

BACKGROUND: Left ventricular hypertrophy (LVH) and microalbuminuria are common in hypertensive patients and are often associated with metabolic syndrome (MetS). However, it is not clear whether MetS could modify the association between cardiac and renal damage. OBJECTIVE: The aim of this study was to assess if the relationship of albumin/creatinine ratio (ACR) and left ventricular mass (LVM) could be independent from MetS in hypertensive overweight/obese patients. METHODS: 180 essential hypertensive and overweight/obese (body mass index [BMI] ≥25 kg/m(2)) patients referred to our Hypertension Centre from January 2006 to April 2009 because of blood pressure (BP) control-related problems were studied. Exclusion criteria were scarce adherence to antihypertensive drug therapy as investigated by the Morisky Medical Adherence Scale (MMAS), heart failure (New York Heart Association III or IV or left ventricular ejection fraction [LVEF] <50%), liver failure, cancer or other systemic severe diseases. MetS was defined according to the National Cholesterol Education Program (USA) Adult Treatment Panel III classification as modified by the American Heart Association. ACR was obtained from first morning urine specimens. Left ventricular dimensions, mass and ejection fraction, were measured by echocardiography following the American Society of Echocardiography recommendations. RESULTS: Patients with microalbuminuria had a 6-fold higher risk for LVH/h(2.7) and 2-fold higher risk for LVH/body surface area (BSA). Univariate linear regression analysis showed a positive relationship between ACR and LVM, expressed both as LVM/h(2.7) or LVM/BSA, as well as a direct correlation between logACR and interventricular diameters and ejection fraction. Regression models including logACR, estimated glomerular filtration rate, BMI, age, hypertension duration, smoking and MetS (as a single variable as well as each single component), showed that only logACR, BMI, hypertension duration and systolic blood pressure (SBP) were independently associated with LVM/h(2.7). CONCLUSION: Along with BP and BMI, albuminuria measured in a morning urine sample as ACR is a valuable low-cost index of cardiac organ damage and increased cardiovascular risk in hypertensive patients independently by MetS. On the other hand, MetS is not an independent risk factor for cardiac damage because it does not seem to add anything more than the sum of each of its components (especially SBP and adiposity indexed by BMI) to the relationship between cardiac and renal subclinical organ damage.