Frequency of metastasis to the gastrointestinal tract determined by endoscopy in a community-based gastroenterology practice.

Metastasis to the gastrointestinal tract is rare. We performed a retrospective analysis to identify patients with metastatic disease to the gastrointestinal tract using two databases containing pathology results from all endoscopic procedures conducted by nearly 200 gastroenterologists in a community setting over a 14-year period. Forty-nine patients were diagnosed with metastasis to the gastrointestinal tract by endoscopy during the study period. Most were women (71%). The most common metastases to the gastrointestinal tract identified by endoscopy were breast cancers (n = 18), followed by melanomas (n = 12), ovarian cancers (n = 7), kidney cancers (n = 5), prostate cancers (n = 2), lung cancer (n = 1), and pancreatic cancer (n = 1). Three patients had unknown primary sites. Among women, the three leading known primary tumor sites were breast, ovary, and melanoma. Among men, the three leading primary tumor sites were melanoma, kidney, and prostate. The stomach was the most common portion of the gastrointestinal tract involved by metastases. Most affected women and were most frequently encountered in the stomach.

Mayo Clinic/Renal Pathology Society Consensus Report on Pathologic Classification, Diagnosis, and Reporting of GN.

Renal pathologists and nephrologists met on February 20, 2015 to establish an etiology/pathogenesis-based system for classification and diagnosis of GN, with a major aim of standardizing the kidney biopsy report of GN. On the basis of etiology/pathogenesis, GN is classified into the following five pathogenic types, each with specific disease entities: immune-complex GN, pauci-immune GN, antiglomerular basement membrane GN, monoclonal Ig GN, and C3 glomerulopathy. The pathogenesis-based classification forms the basis of the kidney biopsy report. To standardize the report, the diagnosis consists of a primary diagnosis and a secondary diagnosis. The primary diagnosis should include the disease entity/pathogenic type (if disease entity is not known) followed in order by pattern of injury (mixed patterns may be present); score/grade/class for disease entities, such as IgA nephropathy, lupus nephritis, and ANCA GN; and additional features as detailed herein. A pattern diagnosis as the sole primary diagnosis is not recommended. Secondary diagnoses should be reported separately and include coexisting lesions that do not form the primary diagnosis. Guidelines for the report format, light microscopy, immunofluorescence microscopy, electron microscopy, and ancillary studies are also provided. In summary, this consensus report emphasizes a pathogenesis-based classification of GN and provides guidelines for the standardized reporting of GN.

Lymphocytic gastritis is not associated with active Helicobacter pylori infection.

BACKGROUND: Lymphocytic gastritis (LG), characterized by marked intra-epithelial lymphocytosis in the gastric mucosa, has been frequently associated with both celiac disease (CD) and H. pylori gastritis. The aim of this study was to review and correlate the morphology of LG with the presence of CD and H. pylori. MATERIALS AND METHODS: Gastric biopsies diagnosed with LG from 1/1/2006 to 8/1/2013 at our institution and corresponding small bowel biopsies, when available, were reviewed for verification of the diagnosis and to assess for the presence of H. pylori and CD. Immunohistochemical (IHC) staining for H. pylori was performed on all gastric biopsies. Demographic, clinical, and laboratory data were obtained from the medical record. RESULTS: Fifty-four of the 56 cases that met inclusion criteria demonstrated significant intra-epithelial lymphocytosis as the predominant histologic abnormality; however, none were associated with H. pylori infection by IHC staining. Two cases that also showed a prominent intra-epithelial and lamina propria neutrophilic infiltrate were both positive for H. pylori and were excluded from further study. Of the 36 small bowel biopsies available, 19 (53%) showed changes in CD. CONCLUSIONS: LG is not a distinct clinicopathologic entity, but a morphologic pattern of gastric injury that can be secondary to a variety of underlying etiologies. When restricted to cases with lymphocytosis alone, LG is strongly associated with CD and not with active H. pylori infection. However, cases that also show significant neutrophilic infiltrate should be regarded as "active chronic gastritis" and are often associated with H. pylori infection. A morphologic diagnosis of LG should prompt clinical and serologic workup to exclude underlying CD.

The optimal number of biopsy fragments to establish a morphologic diagnosis of eosinophilic esophagitis.

OBJECTIVES: Eosinophilic esophagitis (EoE) is characterized clinically by dysphagia, chest pain, and food impaction, and morphologically by increased numbers of intraepithelial eosinophils and marked basal hyperplasia of the squamous mucosa. The consensus criteria for a diagnosis of EoE include the presence of ≥15 eosinophils/HPF in biopsies from both proximal and distal esophagus in the absence of other causes of esophageal eosinophilia, and the lack of clinical response to proton pump inhibitor therapy. Because of the variability in the distribution of intraepithelial eosinophils among biopsy fragments and the lack of standardized biopsy practices, we sought to determine the optimal number of esophageal biopsies from the mid and distal esophagus needed to reach the minimum morphologic criteria of ≥15 eosinophils/HPF. METHODS: From 5 January 2009 to 26 September 2011, 771 patients were diagnosed with EoE at our institution. From that patient population, 102 sequential cases were chosen for further study, all of whom had biopsies taken from the mid and distal esophagus. Cases with only gastric mucosa present and biopsies taken from patients with a previous diagnosis of EoE were excluded. The original H&E-stained slides were reviewed, and the number of biopsy fragments containing squamous mucosa was recorded. By using a × 40 objective and × 10 oculars (field diameter=0.52 mm, field area=0.21 mm(2)), the number of eosinophils per high power field (EOS/HPF) in up to three HPFs was counted in each biopsy fragment. RESULTS: The EOS/HPF were counted in 1,342 biopsy fragments. The number of biopsy fragments obtained from the mid esophagus ranged from 1 to 20 (mean 7; median 7) and those obtained from the distal esophagus ranged from 1 to 18 (mean 6; median 5). There was no significant difference between the mean number of EOS/HPF from the mid (26) and lower (25) esophagus or between the mean peak number of EOS/HPF from the mid (69.1) and lower (60.4) esophagus. The probability of one, four, five, and six biopsy fragments containing >15 EOS/HPF was 0.63, 0.98, 0.99, and >0.99, respectively. CONCLUSIONS: From these data, at least four biopsy fragments should be submitted from the mid and/or proximal esophagus to optimize the chances of a positive diagnosis of EoE in populations not known to have undergone previous proton pump inhibitor therapy. However, the yield is not increased beyond six biopsy fragments. In order to morphologically exclude a diagnosis of reflux esophagitis as the cause of intraepithelial eosinophilia, distal esophageal biopsies, if obtained, must be accompanied by more proximal biopsies (i.e., mid esophagus or higher).

Incidence of diagnostic change in colorectal polyp specimens after deeper sectioning at 2 different laboratories staffed by the same pathologists.

OBJECTIVES: To calculate the incidence of nondiagnostic (ND) colorectal (CR) polyp cases in which deeper tissue sectioning rendered new diagnostic information--particularly adenomas--in 2 laboratories staffed by the same pathologists. METHODS: After initial diagnosis, 100 ND CR polyps from each laboratory were reexamined with 3 deeper levels to establish rates of diagnostic conversion based on biopsy specimen location and original observation(s). RESULTS: Deeper sectioning rendered new diagnostic information in 43 (21.5%) of 200 biopsy specimens and specifically adenomas in 16 (8.0%) of 200 biopsy specimens. CONCLUSIONS: These results support routine ordering of deeper levels on ND CR polyps to improve adenoma detection rates, especially those cases without any histologic abnormality. If another biopsy in the same case already is adenomatous, examination of deeper levels may not be necessary, as it may not have any significant effect on the clinical management of the patient.

Capillary hemangioma of the testis.

Testicular hemangiomas are benign vascular neoplasms usually occurring in children. Pathologists must be aware of this entity when performing intraoperative frozen sections as, after diagnosis, testicle-sparing surgery is adequate. The authors present a typical case with immunohistochemical studies and a review of the literature.

Dense deposit disease associated with monoclonal gammopathy of undetermined significance.

Dense deposit disease (DDD) is a rare glomerular disease that typically affects children, young adults, and much less commonly, older patients. The pathophysiologic process underlying DDD is uncontrolled activation of the alternative pathway (AP) of complement cascade, most frequently secondary to an autoantibody to C3 convertase called C3 nephritic factor, although mutations in factor H and autoantibodies to this protein can impair its function and also cause DDD. Since 1995, we have diagnosed DDD in 14 patients aged 49 years or older; 10 of these patients (71.4%) carry a concomitant diagnosis of monoclonal gammopathy of undetermined significance (MGUS). In 1 of these 10 patients, the index case described here, we evaluated the AP and showed low serum AP protein levels consistent with complement activity, heterozygosity for the H402 allele of factor H, and low levels of factor H autoantibodies, which can affect the ability of factor H to regulate AP activity. In aggregate, these findings suggest that in some adults with MGUS, DDD may develop as a result of autoantibodies to factor H (or other complement proteins) that on a permissive genetic background (the H402 allele of factor H) lead to dysregulation of the AP with subsequent glomerular damage. Thus, DDD in some older patients may be a distinct clinicopathologic entity that represents an uncommon complication of MGUS.

Significance and implications of capillaritis during acute rejection of kidney allografts.

BACKGROUND.: Anti-human leukocyte antigen antibodies (a-HLA) cause graft injury identified by C4d in peritubular capillaries. We investigated whether a-HLA relate to episodes of C4d negative acute rejection (AR). METHODS.: We analyzed 878 kidney recipients transplanted from January 2000 to December 2006. Pretransplant, 36% of these crossmatch negative recipients had a-HLA measured by solid phase assays. RESULTS.: AR occurred in 154 patients (18%) and 11 of them (9.4%) were C4d+. Forty-six percent of ARs were diagnosed by protocol biopsy. The risk of C4d-AR was increased in patients with a-HLA class I with donor specificity (DSA-I) (hazard ratio=1.519; confidence interval, 1.02-2.26; P=0.039). DSA-II were not associated with an increased risk of C4d-AR. The relationship between DSA-I and C4d-AR was independent of recipient age, BK nephropathy, and HLA mismatches. Compared with DSA-, in DSA+ recipients C4d-AR were most often histologically "borderline." DSA+ was associated with capillaritis in the biopsy (glomerulitis, 6.1% vs. 32%, P=0.003; peritubular capillaritis: 13% vs. 40%, P=0.0009). Compared with no AR, C4d-AR with capillaritis was associated with reduced graft survival (hazard ratio=4.164; confidence interval, 1.763-9.832; P=0.001), independent of other variables. This association was observed even in the cases of borderline AR. CONCLUSIONS.: DSA-I increases the risk of C4d-AR. The presence of DSA-I or II is associated with capillaritis during AR. Capillaritis is associated with reduced graft survival.

Renal failure due to combined cast nephropathy, amyloidosis and light-chain deposition disease.

Renal dysfunction commonly occurs in multiple myeloma (MM) and is caused by deposition of abnormal light chain within various compartments of the kidney. Renal pathologic findings are diverse and include cast nephropathy (CN), amyloidosis and light-chain deposition disease (LCDD). We report a case of renal failure in a patient with MM caused by concurrent CN, amyloidosis and LCDD which has not been previously described.

CCND1 rearrangements and cyclin D1 overexpression in renal oncocytomas: frequency, clinicopathologic features, and utility in differentiation from chromophobe renal cell carcinoma.

SUMMARY: Renal oncocytoma is a benign tumor occurring singly or as multiple synchronous lesions. The histologic features of renal oncocytoma may overlap with those of chromophobe renal cell carcinoma. Chromosomal translocations involving the CCND1 locus at 11q13 and overexpression of cyclin D1 occur in a subset of renal oncocytomas. We evaluated a series of 63 renal oncocytomas and 36 chromophobe renal cell carcinomas and assessed the clinical features, cyclin D1 overexpression by immunohistochemistry, and alterations of the CCND1 gene by fluorescence in situ hybridization. All 36 chromophobe renal cell carcinomas were negative for cyclin D1 overexpression and alterations of CCND1. Of the 63 renal oncocytomas, 21 (33%) showed cyclin D1 overexpression. Of 21 renal oncocytomas with cyclin D1 overexpression, a CCND1 rearrangement was detected in 12 (57%). A CCND1 rearrangement was also identified in 1 (2%) of the 42 renal oncocytomas without cyclin D1 overexpression. Of 42 renal oncocytomas without cyclin D1 overexpression, 16 (38%) were from patients with multiple renal oncocytomas at nephrectomy. Of 21 renal oncocytomas with cyclin D1 overexpression, only 1 (5%) patient had multiple renal oncocytomas (P = .006). Of the 25 patients whose original tumor showed no cyclin D1 overexpression, 8 (32%) developed a subsequent renal oncocytoma. None of 15 patients whose original tumor showed cyclin D1 overexpression had a subsequent renal oncocytoma (P = .016). The findings of this study suggest that renal oncocytomas lacking cyclin D1 overexpression may be associated with the development of multiple renal oncocytomas and that these patients are more likely to develop subsequent renal oncocytomas suggesting the need for more frequent clinical for these patients and little need for follow-up in patients with renal oncocytomas overexpressing cyclin D1. The data also show that cyclin D1 overexpression and CCND1 rearrangements by fluorescence in situ hybridization are absent in chromophobe renal cell carcinoma, suggesting that these are useful when differentiating between renal oncocytoma and chromophobe renal cell carcinoma.

Long-term outcome of kidney transplantation in patients with fibrillary glomerulonephritis or monoclonal gammopathy with fibrillary deposits.

To determine the outcome of kidney transplantation in patients with fibrillary glomerulonephritis (FGN), a rare glomerular disease, we followed 12 patients, 5 with FGN and 7 patients with monoclonal gammopathy and fibrillary deposits (MGFD), who underwent 15 kidney transplants since 1988 with a median follow-up of 52 months. Recurrent disease did not arise in any of the patients with FGN but developed in 5 patients with MGFD. Seven allografts failed: 1 in the FGN group and 6 in the MGFD group. Median allograft survival for patients with MGFD was 37 months but had not been reached in FGN patients. One patient with FGN had primary allograft failure secondary to graft thromboembolism. Three patients with MGFD were re-transplanted and one lost the second allograft to recurrent disease, but the other two died from hematological malignancy. Another patient was diagnosed with MPGN type III and did not have detectable fibrillary material 22 months after transplantation. One patient with MGFD had stable allograft function 6 months post-transplant but another, with recurrent disease, underwent peripheral blood stem cell transplantation and regained stable allograft function. Our study shows that kidney transplantation appears safe in patients with FGN with little risk of recurrence. However, patients with MGFD have a significant risk for disease recurrence. Whether the development of hematological malignancies following transplantation in this group is related to their original disease or was coincidental requires further studies.

Induction of heme oxygenase-1 and ferritin in the kidney in warm antibody hemolytic anemia.

Warm antibody autoimmune hemolytic anemia usually is associated with extravascular hemolysis. We report a case of a 42-year-old man with sustained and moderately severe warm antibody autoimmune hemolytic anemia, hemoglobinuria, hemosiderinuria, and acute kidney injury. We show marked induction of heme oxygenase-1 and increased ferritin expression in renal tubules, along with increased iron deposition in renal proximal tubules. These findings in this clinical case thus recapitulate those observed in experimental models of heme protein-induced kidney injury in which a coupled induction of heme oxygenase-1 and ferritin occurs in the kidney. We discuss the pathobiological significance of these findings and suggest that this linked response confers cytoprotection to the kidney exposed to hemoglobin and mitigates the severity of acute kidney injury that may otherwise occur. Finally, this case report documents that nephrotic-range proteinuria can occur in patients with autoimmune hemolytic anemia complicated by hemoglobinuria.

Bleeding complications after transcutaneous kidney biopsy in patients with systemic amyloidosis: single-center experience in 101 patients.

BACKGROUND: Bleeding is one of the most common complications after kidney biopsy. Amyloidosis is thought to be 1 of the risk factors, but this has not been confirmed in a large study. We performed this study to assess the risk of bleeding after kidney biopsy in patients with amyloidosis. STUDY DESIGN: Retrospective study. SETTINGS & PARTICIPANTS: 101 patients with and 188 patients without amyloidosis undergoing outpatient percutaneous kidney biopsy at a major medical center in the absence of abnormal partial thromboplastin time, prothrombin time international normalized ratio, or platelet count and/or uncontrolled hypertension. PREDICTOR: Clinical diagnosis of amyloidosis. OUTCOMES & MEASUREMENTS: Post-kidney biopsy bleeding confirmed by means of imaging. Bleeding was defined as major if it required blood transfusion, hospital admission, or other invasive procedures and minor if none of these interventions were needed. RESULTS: Post-kidney biopsy bleeding was observed in 9.9% of patients with amyloidosis and 10.6% of controls (P = 0.8). Bleeding was major in 4% of patients with amyloidosis and 2.1% of controls (P = 0.4). Three patients from each group required blood transfusions and selective renal angiography. All except 1 patient from the control group underwent embolization. LIMITATIONS: Retrospective data analysis and overall low event rate did not allow for independent risk-factor analysis. CONCLUSIONS: The present study suggests that in the absence of a hematostatic disorder and/or uncontrolled hypertension, bleeding risk during kidney biopsy is not increased in patients with systemic amyloidosis. Kidney biopsy can be performed safely using the same screening criteria as for patients without amyloidosis.

BK virus-associated nephropathy in a patient with AIDS.

The BK virus is a ubiquitous member of the group of human polyoma viruses that commonly is reactivated in the setting of immunosuppression related to renal transplantation, which results in tubulointerstitial nephritis and allograft dysfunction. BK virus-associated nephropathy occurring in association with human immunodeficiency virus infection and acquired immunodeficiency syndrome (AIDS) was reported only rarely. We describe the case of a 43-year-old man with AIDS presenting with nonoliguric renal failure. The renal biopsy specimen showed tubulointerstitial nephritis and renal tubular cell changes consistent with BK viral inclusions. Results of in situ hybridization for BK viral DNA were positive and showed tubular cell intranuclear inclusions. To our knowledge, this represents the third case of AIDS-associated BK virus-associated nephropathy diagnosed by means of biopsy.

Malignant mixed epithelial and stromal tumor of the kidney with rhabdoid features: report of a case including immunohistochemical, molecular genetic studies and comparison to morphologically similar renal tumors.

Mixed epithelial stromal tumor of the kidney (MEST)/adult cystic nephroma (CN) is a lesion characterized by epithelial lined tubular or cystic structures interspersed within a variably prominent, distinctive spindle-cell stroma. Although typically benign, cases with malignant features have been reported. Herein, we report a MEST/CN with malignant stromal features and rhabdoid differentiation arising in the left kidney of an 84-year-old woman. Histologically, the tumor displayed multiple tubules and variably sized cystic structures lined by benign epithelium with an intervening malignant-appearing spindle-cell stroma. The malignant stroma displayed condensation in the regions surrounding the epithelial component consistent with the ovarian-like stroma typically observed in MEST/CN. In addition, the stromal cells displayed extensive rhabdoid differentiation. Immunohistochemical analysis revealed strong expression of cytokeratin 7, CAM 5.2, AE1/AE3, wide-spectrum keratin, and epithelial membrane antigen by the epithelial component. The stromal component displayed strong immunohistochemical expression of WT-1, CD-99, CD-56, INI1, and estrogen receptor; focal actin positivity; and was negative for desmin, myogenin, and progesterone receptor. Analysis by reverse transcriptase polymerase chain reaction failed to identify the SYT-SSX1 or SYT-SSX2 fusion transcripts characteristic of synovial sarcoma. To our knowledge, this represents the first report in the literature of malignant MEST with rhabdoid features and suggests that this entity should be considered in the diagnosis of renal stromal malignancies with prominent rhabdoid features.

Molecular diagnostics of Meckel-Gruber syndrome highlights phenotypic differences between MKS1 and MKS3.

Meckel-Gruber syndrome (MKS) is a recessively inherited, lethal disorder characterized by renal cystic dysplasia, occipital encephalocele, polydactyly and biliary dysgenesis. MKS is genetically heterogeneous with three loci mapped and two identified; MKS1 (17q23) and MKS3 (8q22.1). MKS1 is part of the Finnish disease heritage, while MKS3 has been described exclusively in consanguineous Asian families. Here we aimed to establish molecular diagnostics for MKS, determine the importance of MKS1 and MKS3 in non-consanguineous populations, and study genotype/phenotype correlations. The coding regions of MKS1 and MKS3 were screened for mutations by direct sequencing in 17 families clinically diagnosed with MKS in the US or The Netherlands. The clinical phenotype was compared to genic and allelic effects. Both mutations were identified in ten families; five MKS1 and five MKS3. All but two were compound heterozygotes, consistent with their non-consanguineous nature. The MKS1-Fin(major) mutation accounted for 7/10 MKS1 mutations; two novel changes were additionally detected. Seven novel mutations were found in MKS3, including three missense changes. We concluded that MKS1 and MKS3 account for the majority of MKS in non-consanguineous populations of European origin. Polydactyly is usually found in MKS1 but rare in MKS3. Cases with no, or milder, CNS phenotypes were only found in MKS3; hypomorphic missense mutations may be associated with less severe CNS outcomes. This study is consistent with further genetic heterogeneity of MKS, but underlines the value of molecular diagnostics of the known genes to aid family planning decisions.

Fabry disease: a morphologic study of 11 cases.

Fabry disease is a metabolic disorder caused by the genetic deficiency of alpha-galactosidase A. Deposition of glycosphingolipids in podocytes, endothelial cells, and other cell types leads to formation of myelin-like inclusions, which are the hallmark of the disease. In most untreated males, the disorder progresses to end-stage kidney disease. Fabry disease is rare, and no renal biopsy series focusing on pathologic findings has been published in the past 25 years. We retrieved kidney biopsies diagnosed with Fabry disease from our files, and reviewed clinical data as well as the light and electron microscopy. In total, 11 patients were identified: six male subjects aged 17-43 years and five female subjects aged 30-73 years. On average, male patients presented more than 10 years earlier then female patients. A total of 10 patients had proteinuria, two with the nephrotic syndrome. Four male and three female patients had decreased renal function. Light microscopy showed vacuolization of the podocyte cytoplasm and variable glomerular sclerosis. Older patients and males had more advanced glomerular and interstitial sclerosis, but three of the five female patients also had advanced renal disease. Electron microscopy showed the characteristic myelin-like inclusions most prominently in the podocyte cytoplasm. Seven patients also had podocyte foot process effacement. A second type of deposit, unexpected and conspicuous, was identified in three males, and found to be associated with glomerular basement membrane duplications. These deposits were composed of layered membrane-like material, and therefore morphologically distinct from myelin-like inclusions. They probably represent remnants of damaged endothelial cells.

Collapsing and non-collapsing focal segmental glomerulosclerosis in kidney transplants.

BACKGROUND: The aetiological and clinical associations of collapsing focal segmental glomerulosclerosis (cFSGS) following kidney transplantation (KTx) are poorly described. In this study, post-transplant cFSGS and non-collapsing FSGS (ncFSGS) were compared in recent KTx recipients. Evidence for intragraft viral infection was sought. METHODS: Twenty-nine cases of post-KTx FSGS were identified and classified as cFSGS (n = 10) or ncFSGS (n = 19). Biopsies were scored using Banff '97 criteria and subjected to in situ hybridization (ISH) for parvovirus B19 (pvB19), simian virus 40 (SV40) and BK virus (BKV). RESULTS: cFSGS and ncFSGS patients were comparable for age, gender, weight, delayed function, human leucocyte antigen (HLA) matching, acute rejection and median time to diagnosis. Deceased donor source was more common among cFSGS cases (70 vs 32%, P = 0.05). FSGS was recurrent in 2/10 cFSGS cases compared with 8/19 ncFSGS (P = NS). cFSGS was associated with more proteinuria (11.9 vs 7.2 g/day, P = 0.05) and higher serum creatinine (4.2 vs 1.9 mg/dl, P = 0.0001) at diagnosis. Plasmapheresis was used in two out of 10 cFSGS and seven out of 19 ncFSGS cases with treatment response in 0 of two and three of seven, respectively. Graft loss was more rapid with cFSGS compared with ncFSGS (P = 0.02). Histologically, cFSGS was associated with more severe chronic vascular abnormalities. All biopsies were negative for pvB19, SV40 and BKV by ISH. CONCLUSIONS: cFSGS following KTx presents with higher proteinuria, diminished renal function, more severe vascular disease and higher rate of graft loss compared with the non-collapsing form. There was no evidence for infection by pvB19 or polyomaviruses.

Anti-glomerular basement membrane glomerulonephritis: a morphologic study of 80 cases.

Anti-glomerular basement membrane (anti-GBM) glomerulonephritis is a rare disease caused by IgG autoantibodies against the glomerular basement membrane. We describe clinical and pathologic findings in a series of renal biopsy specimens from 80 patients. The patients ranged in age from 16 to 87 years. The age distribution was bimodal, with one peak at a young age predominated by males and a second peak in the sixth to eighth decades with females predominating. Most patients (70 [88%]) had severe necrotizing glomerulonephritis with crescents in more that 50% of glomeruli. The fraction of crescentic glomeruli in biopsy specimens correlated well with serum creatinine levels but not with serologic titers for anti-GBM antibodies. Interstitial fibrosis was uncommon and, when present, minimal to mild. Linear IgG deposition defines this entity, but immunofluorescent costaining for other immunoglobulins and complement is found frequently. To our knowledge, this is the largest series of renal biopsy specimens with anti-GBM glomerulonephritis studied to date.