Clinical characteristics and long-term prognosis of type 1 gastric neuroendocrine tumors in a large Japanese national cohort.

OBJECTIVES: Optimal management of type 1 gastric neuroendocrine tumors (T1-GNETs) remains unknown, with few reports on their long-term prognosis. This study investigated the clinical characteristics and long-term prognosis of T1-GNETs. METHODS: We reviewed the medical records of patients diagnosed with T1-GNET during 1991-2019 at 40 institutions in Japan. RESULTS: Among 172 patients, endoscopic resection (ER), endoscopic surveillance, and surgery were performed in 84, 61, and 27, respectively, including 27, 77, and 2 patients with pT1a-M, pT1b-SM, and pT2 tumors, respectively. The median tumor diameter was 5 (range 0.8-55) mm. Four (2.9%) patients had lymph node metastasis (LNM); none had liver metastasis. LNM rates were significantly higher in tumors with lymphovascular invasion (LVI) (15.8%; 3/19) than in those without (1.1%; 1/92) (P = 0.016). For tumors <10 mm, LVI and LNM rates were 18.4% (14/76) and 2.2% (2/90), respectively, which were not significantly different from those of tumors 10-20 mm (LVI 13.3%; 2/15, P = 0.211; and LNM 0%; 0/17, P = 1.0). However, these rates were significantly lower than those of tumors >20 mm (LVI 60%; 3/5, P = 0.021; and LNM 40%; 2/5, P = 0.039). No tumor recurrence or cause-specific death occurred during the median follow-up of 10.1 (1-25) years. The 10-year overall survival rate was 97%. CONCLUSIONS: Type 1 gastric neuroendocrine tumors showed indolent nature and favorable long-term prognoses. LVI could be useful in indicating the need for additional treatments. ER for risk prediction of LNM should be considered for tumors <10 mm and may be feasible for tumors 10-20 mm. TRIAL REGISTRATION: The study protocol was registered in the University Hospital Medical Information Network (UMIN) under the identifier UMIN000029927.

Integrated genetic and epigenetic analysis of cancer-related genes in non-ampullary duodenal adenomas and intramucosal adenocarcinomas.

The molecular and clinical characteristics of non-ampullary duodenal adenomas and intramucosal adenocarcinomas are not fully understood because they are rare. To clarify these characteristics, we performed genetic and epigenetic analysis of cancer-related genes in these lesions. One hundred and seven non-ampullary duodenal adenomas and intramucosal adenocarcinomas, including 100 small intestinal-type tumors (90 adenomas and 10 intramucosal adenocarcinomas) and 7 gastric-type tumors (2 pyloric gland adenomas and 5 intramucosal adenocarcinomas), were investigated. Using bisulfite pyrosequencing, we assessed the methylation status of CpG island methylator phenotype (CIMP) markers and MLH1. Then using next-generation sequencing, we performed targeted exome sequence analysis within 75 cancer-related genes in 102 lesions. There were significant differences in the clinicopathological and molecular variables between small intestinal- and gastric-type tumors, which suggests the presence of at least two separate carcinogenic pathways in non-ampullary duodenal adenocarcinomas. The prevalence of CIMP-positive lesions was higher in intramucosal adenocarcinomas than in adenomas. Thus, concurrent hypermethylation of multiple CpG islands is likely associated with development of non-ampullary duodenal intramucosal adenocarcinomas. Mutation analysis showed that APC was the most frequently mutated gene in these lesions (56/102; 55%), followed by KRAS (13/102; 13%), LRP1B (10/102; 10%), GNAS (8/102; 8%), ERBB3 (7/102; 7%), and RNF43 (6/102; 6%). Additionally, the high prevalence of diffuse or focal nuclear ß-catenin accumulation (87/102; 85%) as well as mutations of WNT pathway components (60/102; 59%) indicates the importance of WNT signaling to the initiation of duodenal adenomas. The higher than previously reported frequency of APC gene mutations in small bowel adenocarcinomas as well as the difference in the APC mutation distributions between small intestinal-type adenomas and intramucosal adenocarcinomas may indicate that the adenoma-carcinoma sequence has only limited involvement in duodenal carcinogenesis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Prognostic significance of tumor budding, poorly differentiated cluster, and desmoplastic reaction in endometrioid endometrial carcinomas.

AIMS: The tumor budding (TB); poorly differentiated cluster (PDC); desmoplastic reaction (DR); and microcystic, elongated, and fragmented (MELF) patterns of invasion are pathological findings at the tumor invasion front associated with epithelial-to-mesenchymal transition. This study aimed to clarify the clinical significance of the TB, PDC, DR, and MELF patterns in endometrioid endometrial carcinomas (EEC). METHODS: Two hundred and eight cases of histologically proven EEC retrieved from the archives of the Department of Pathology, Fukui Prefectural Hospital, and diagnosed between January 2000 and August 2020 were retrospectively analyzed. RESULTS: The TB, PDC, DR, and MELF patterns were identified in 29 (13.9%), 47 (22.6%), 45 (21.6%), and 23 (11.1%) cases, respectively. Kaplan-Meier curve analysis with log-rank test demonstrated that TB, PDC, and DR were associated with a lower progression-free survival (p = 0.010, 0.002, and <0.0001, respectively), whereas the MELF pattern did not show any association (p = 0.668). In multivariate analyses, only DR was significantly associated with lower progression-free survival (p = 0.034). Moreover, only PDC was associated with lower overall survival in univariate analysis (p = 0.018), but the association lost significance in multivariate analysis. CONCLUSIONS: The present study revealed that the histological confirmation of TB, PDC, and DR at the tumor invasive front predicts poor prognosis in EEC. However, the MELF pattern was not a predictor of poor prognosis in EEC.

Risk for lymph node metastasis in Epstein-Barr virus-associated gastric carcinoma with submucosal invasion.

OBJECTIVES: Epstein-Barr virus-associated gastric cancer (EBVGC) has been reported to be associated with a low risk for lymph node metastasis (LNM). However, the curative criteria for endoscopic submucosal dissection (ESD) for submucosal EBVGC (pT1b-EBVGC) remain unclear. Our study aimed to investigate the risk factors for LNM in pT1b-EBVGC. METHODS: This was a retrospective multicenter study at five institutes in Japan. We reviewed medical records and extracted all pT1b-EBVGC cases that met the following criteria: (i) histologically proven submucosal gastric cancer; (ii) surgical or endoscopic resection between January 2000 and December 2016; and (iii) presence of Epstein-Barr virus (EBV) in tumor cells verified by EBV-encoded small RNA in situ hybridization (EBER-ISH). The association between clinicopathological factors and LNM were assessed using multivariable logistic regression analysis. RESULTS: A total of 185 pT1b-EBVGC cases were included in the analysis. LNM was found in nine cases (4.9%). Multivariable logistic regression analysis demonstrated that lymphatic invasion (OR 9.1; 95% CI 2.1-46.1) and submucosal invasion ≥4000 µm (OR 9.2; 95% CI 1.3-110.3) were significant risk factors for LNM. When we focused on pT1b-EBVGC without lymphatic invasion and with submucosal invasion <2000 µm, the rate of LNM was 0% (0/96, 95% CI 0-3.8%). CONCLUSIONS: Our findings indicated that lymphatic invasion and submucosal invasion ≥4000 µm were significant risk factors for LNM. ESD could be an appropriate option for pT1b-EBVGC without lymphatic invasion and with submucosal invasion <2000 µm.

Efficacy of Endoscopic Evaluation of Acute Radiation Esophagitis during Chemoradiotherapy with Proton Beam Therapy Boost for Esophageal Cancer.

BACKGROUND/AIM: To evaluate the utility of endoscopy for assessing radiation esophagitis during chemoradiotherapy (CRT) with proton beam therapy (PBT) boost for esophageal cancer. METHODS: Between December 2012 and December 2016, 38 patients with esophageal cancer were treated with CRT with PBT boost. To evaluate radiation esophagitis, endoscopy was performed after administration of CRT with standard PBT boost (total dose 50-60 Gy relative biological effectiveness [RBE]). Radiation esophagitis was evaluated and classified into 5 newly developed endoscopic grades (Fukui Acute Radiation Esophagitis [FARE] grade). The additional PBT boost was then adjusted and delivered (2-20 Gy [RBE]) to a maximum total dose of 74.4 Gy (RBE) based on the degree of radiation esophagitis, probability of residual tumor, and patient's general condition. To evaluate the utility of endoscopic examination, the incidences of adverse events graded according to National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE, version 4.0) were determined at the time of endoscopic examination after CRT with standard PBT boost (50-60 Gy [RBE]) and at the completion of treatment (60-74.4 Gy [RBE]), as well as during the 90 days from the beginning of treatment. RESULTS: There was a significant correlation between FARE grade and CTCAE esophagitis grade (ρ = 0.48; p = 0.03). Moreover, endoscopy detected severe esophagitis in an asymptomatic patient. Radiation dose escalation was achieved without severe acute adverse events. There was no significant difference between the incidence of acute toxicity at the time of the CRT with standard PBT boost (50-60 Gy [RBE]) and the higher dose at the completion of treatment (60-74.4 Gy [RBE]), which suggests this dose escalation strategy is safe. CONCLUSION: Endoscopic evaluation of radiation esophagitis using FARE grades was safely performed and useful for adjusting added radiation to ensure the safety of escalations in CRT with PBT boost for esophageal cancer.

[Neoadjuvant Proton Beam Chemoradiotherapy for Locally Advanced Gall Bladder Cancer-A Case Report].

A 67-year-old man visited our hospital due to progressing appetite loss and fever. He presented with a fist-sized palpable mass in his right hypochondrium. Abdominal CT showed a 10 cm diameter tumor that originated from the gall bladder infiltrating the abdominal wall, liver, duodenum, and colon. Blood tests revealed leukocytosis, elevated C-reactive protein level, and severe malnutrition. FDG-PET showed markedly high uptake in the tumor and diffuse uptake in the spine. Owing to the inability of oral intake, he underwent laparoscopic gastrojejunostomy and intraoperative tumor biopsy, which demonstrated pathologically G-CSF-producing carcinoma in the gall bladder. For the rapidly progressive tumor, he underwent proton beam chemoradiotherapy as preoperative treatment. The tumor markedly shrunk with dramatic improvement of his inflammatory and nutritional status. Consequently, R0 resection could be performed by combination surgeries of right hemi-colectomy, pancreatoduodenectomy, and partial liver resection. He received adjuvant chemotherapy and was alive without recurrence 12 months after tumor resection. To our knowledge, this is the first report of the use of neoadjuvant proton beam chemoradiotherapy in biliary cancer.

[A Case of Pathological Complete Response Following Neoadjuvant Chemotherapy with Gemcitabine plus Nab-Paclitaxel in Borderline Resectable Pancreatic Cancer].

We report a resected case with a pathological complete response(pCR)after neoadjuvant chemotherapy for borderline resectable pancreatic cancer(BRPC). A 67-year-old woman who had been treated for type 2 diabetes mellitus in our hospital presented with an exacerbation of diabetes. An abdominal CT scan confirmed a hypovascular mass in the pancreas body consistent with BRPC. After 3 courses of chemotherapy with gemcitabine plus nab-paclitaxel(GnP), her elevated DUPAN-2 level normalized. A follow up CT scan revealed that the tumor had decreased in size, and no distant metastasis was detected. Distal pancreatectomy with en-bloc celiac axis resection was performed. Histopathological examination of the resected specimens showed no evidence of residual cancer cells(pCR). The patient remains disease-free 8 months after surgery. Neoadjuvant GnP chemotherapy may be useful for BRPC.

A case of Trousseau syndrome associated with a mucosa-associated lymphoid tissue lymphoma disseminated to the mesenteric adipose tissue.

A 66-year-old man with recurrent stroke within a short period of time was referred to our department from the neurology department to rule out any malignancy. An endoscopic examination revealed a white depressed lesion in the body of the stomach, and computed tomography revealed a high-density area in the mesentery around the stomach. A mucosa-associated lymphoid tissue (MALT) lymphoma was detected from both the stomach biopsy and resected mesenteric specimen. Systemic chemotherapy was administered for the MALT lymphoma (Lugano classification stage IV). Cerebral infarction did not occur after the treatment. We concluded that Trousseau syndrome associated with the MALT lymphoma disseminated to the mesenteric adipose tissue. A MALT lymphoma has a small probability of occurring in Trousseau syndrome.

Intrathoracic vagus nerve tumor: case report and review of the literature.

We present the case of a 23-year-old female with benign intrathoracic vagal neurofibroma associated with von Recklinghausen's disease. We reviewed 87 other neurogenic tumors of the intrathoracic vagus nerve and discuss the incidence rate of complications, especially the relationship between tumor location, tumor size, and preservation of the nerve in this case report.

Management and clinical outcomes of type I gastric carcinoid patients: retrospective, multicenter study in Japan.

BACKGROUND AND AIM: Type I gastric carcinoids (TIGC) are associated with chronic atrophic gastritis (CAG) with hypergastrinemia and hyperplasia of enterochromaffin-like cells. Several treatment options are currently available for these tumors including total gastrectomy, partial resection, antrectomy, endoscopic resection and endoscopic surveillance. The present study evaluated different treatment approaches and clinical outcomes of patients with TIGC in Japan. METHODS: Between 1991 and 2011, 82 patients with TIGC were identified at multicenter institutions in Japan. Patient demographics, tumor size, depth of invasion, vessel involvement, treatment approach, Helicobacter pylori infection, serum gastrin level, recurrence-free survival (RFS) and disease-specific survival (DSS) were analyzed. RESULTS: Median age of all patients at the time of diagnosis was 56 years (range, 24-79 years). There were 44 males and 38 females. Patients underwent endoscopic surveillance (n=25), endoscopic resection (n=41) or surgical resection (n=16). Intramucosal invasion was found in 19 patients, submucosal invasion in 44 patients and muscularis propria invasion in one patient. Tumor diameter was ≤ 10 mm in 71 patients, 11-20mm in five patients and ≥ 21 mm in five patients. None of the patients showed rapidly growing tumors, local recurrence or metastasis. The median (range) follow-up period was 7(0-20) years. RFS was 97.6% and DSS was 100% in all the patients. CONCLUSION: The prognosis of TIGC patients treated by different modalities in Japan is favorable regardless of the generational change of management for TIGC.

[Case of acute necrotizing esophagitis associated with AA amyloidosis secondary to bronchiectasis].

An 82-year-old woman with a history of bronchiectasis for 20 years was admitted to our hospital with anorexia and diarrhea. Sigmoidoscopy showed multiple mucosal erythematous areas and erosions. Histologic examination with Congo red stain revealed massive amyloid deposition around the submucosal vessels as well as in the parenchyma of the mucosa and submucosa. With immunohistochemistry, the diagnosis of secondary/reactive AA amyloidosis was confirmed. Esophagogastroduodenoscopy demonstrated diffuse dark brown mucosa, establishing the diagnosis of acute necrotizing esophagitis. Ischemia associated with amyloid deposition of the vessels in the esophagus was considered to be a possible etiology of acute necrotizing esophagitis. Additionally, gastric outlet obstruction and gastroesophageal reflux associated with gastroduodenal erosions caused by amyloid deposition were supposed to be another factor. Amyloid deposition in the esophageal mucosa may cause a reduction in mucosal defense that is responsible for the pathogenesis. We report the first case of acute necrotizing esophagitis associated with amyloidosis.

Treatment of a Desmoid Tumor That Enlarged During Pregnancy: A Case Report and Literature Review.

Desmoid tumors are rare soft-tissue tumors that exhibit locoregional aggressiveness and a high local recurrence rate following initial resection. No fixed recommendations have been established with regard to the timing and method of treatment for desmoid tumors that enlarge during pregnancy. Desmoid tumors tend to enlarge during pregnancy, and most do not regress spontaneously postpartum. Thus, surgery may be required even during pregnancy. We report a case of an abdominal wall desmoid tumor that grew to 90 mm during pregnancy and was resected at 17 weeks of gestation. Marginal resection was performed, and the surgical margin was microscopically positive. The postoperative course and the pregnancy were uneventful, and no recurrence was observed at the 15-month follow-up visit.

A case of focal nodular hyperplasia-like lesion presenting unusual signal intensity on the hepatobiliary phase of gadoxetic acid-enhanced magnetic resonance image.

Focal nodular hyperplasia (FNH) or FNH-like lesions of the liver are benign lesions that can be mostly diagnosed by hepatobiliary phase gadoxetic acid-enhanced magnetic resonance imaging (MRI). Accurate imaging diagnosis is based on the fact that most FNHs or FNH-like lesions show characteristic hyper- or isointensity on hepatobiliary phase images. We report a case of an FNH-like lesion in a 73-year-old woman that mimicked a malignant tumor. Dynamic contrast-enhanced computed tomography (CT) and MRI using gadoxetic-acid revealed an ill-defined nodule showing early enhancement in the arterial phase and gradual and prolonged enhancement in the portal and equilibrium/transitional phases. Hepatobiliary phase imaging revealed inhomogeneous hypointensity, accompanied by a slightly isointense area compared to the background liver. Angiography-assisted CT showed a portal perfusion defect of the nodule, inhomogeneous arterial blood supply in the early phase, and less internal enhancement in the late phase, accompanied by irregularly shaped peritumoral enhancement. No central stellate scar was identified in any of the images. Imaging findings could not exclude the possibility of hepatocellular carcinoma, but the nodule was pathologically diagnosed as an FNH-like lesion by partial hepatectomy. In the present case, an unusual inhomogeneous hypointensity on hepatobiliary phase imaging made it difficult to diagnose the FNH-like lesions.

[A case of advanced gastric cancer with tumor embolus in the portal vein successfully treated with S-1 and CDDP therapy].

A 50-year-old man with advanced gastric cancer and a tumor embolus in the portal vein was referred to our hospital. We diagnosed the tumor as cStage III B (cT3, cN2, cH0, P0, M0) gastric cancer, and selected neoadjuvant S-1 (80 mg/m2) and CDDP (60 mg/m2) therapy for him. After 2 courses of chemotherapy, the embolus in the portal vein disappeared. After additional chemotherapy, the primary tumor and regional lymph node revealed a partial response (PR), and judging from the results from the barium meal study, upper GI endoscopic findings and CT scan, a total gastrectomy with lymph node dissection was performed.

[Type 4 advanced gastric cancer responding to histological complete response after neoadjuvant S-1 combined with CDDP therapy-report of a case].

A 75-year-old man with type 4 advanced gastric cancer was referred to our hospital. We diagnosed the tumor as cStage III B(cT4a, cN2, cM0)gastric cancer. We selected neoadjuvant S-1 combined with CDDP therapy for him. After 2 courses of chemotherapy, the extension of the gastric wall improved. After an additional 2 courses of chemotherapy, the primary tumor revealed a partial response(PR), judged from a barium meal study and upper GI endoscopic findings, and a total gastrectomy with lymph node dissection was performed. The pathological specimens showed no cancer cells in the gastric wall and lymph nodes, so the histological effect was judged as Grade 3.

Pearls and pitfalls of imaging features of pancreatic cystic lesions: a case-based approach with imaging-pathologic correlation.

A variety of neoplastic and non-neoplastic lesions of the pancreas can present with a predominantly cystic architecture. These lesions are increasingly being detected as incidental findings on routine cross-sectional imaging following technological advances in these techniques and their widespread use. The different histopathological behaviors show various common and uncommon imaging findings, and some cases show similar appearance in spite of different histopathology. Each lesion requires specific management because of the differing risk of progression to malignancy, and an accurate imaging diagnosis is crucial. The typical imaging characteristics that differentiate pancreatic cystic lesions have been well described and fully summarized. However, in addition to a small percentage of cases that shows uncommon imaging findings, a substantial percentage of cystic lesions shows overlapping imaging findings that can lead to radiological misdiagnosis. For appropriate diagnosis and optimal treatment strategy, it is important to know the uncommon and overlapping imaging findings of these lesions, in addition to familiarity with the typical aspects. In this article, we reconfirm the well-known characteristic imaging features of pancreatic cystic lesions and present several diagnostically challenging cases, focusing on the uncommon and overlapping imaging findings.

Significance of gene mutations in the Wnt signaling pathway in traditional serrated adenomas of the colon and rectum.

Recent studies have shown that colorectal serrated lesions, which include sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs), are precursors of colorectal cancer. However, the molecular mechanisms underlying the carcinogenesis, particularly in TSAs, remain largely uncharacterized. To clarify their molecular and clinicopathological characteristics, we performed mutation and methylation analyses of cancer-associated genes in 78 serrated lesions, including TSAs, SSAs and microvesicular hyperplastic polyps. Target exon sequence analysis was performed with 39 genes, including genes known to be frequently mutated in colorectal cancers and/or serrated lesions. We also used bisulfite pyrosequencing to assess the methylation status of various cancer-associated genes and marker genes of the CpG island methylator phenotype (CIMP). The prevalence of mutations in genes associated with Wnt signaling was significantly higher in TSAs than SSAs (65% vs. 28%, p < 0.01). Among those, RNF43 mutations were observed in 38% of TSAs and 17% of SSAs. In immunohistochemical studies of 39 serrated lesions, the prevalence of abnormal nuclear ß-catenin accumulation was significantly higher in TSAs (57%) than SSAs (8%) (P = 0.01). SMOC1 methylation was detected in 54% of TSAs but in no SSAs (p < 0.01). Additionally, SMOC1 methylation was more prevalent among TSAs with KRAS mutation (82%) than with BRAF mutation (38%, p = 0.03). Lesions with CIMP-high or RNF43 mutations were detected only in TSAs with BRAF mutation, suggesting two distinct carcinogenic pathways in TSAs. Mutations in genes associated with Wnt signaling play a greater role in the carcinogenesis of TSAs than SSAs.

Real-time PCR-based method for the rapid detection of extended RAS mutations using bridged nucleic acids in colorectal cancer.

Mutations in RAS and BRAF are predictors of the efficacy of anti-epidermal growth factor receptor (EGFR) therapy in patients with metastatic colorectal cancer (mCRC). Therefore, simple, rapid, cost-effective methods to detect these mutations in the clinical setting are greatly needed. In the present study, we evaluated BNA Real-time PCR Mutation Detection Kit Extended RAS (BNA Real-time PCR), a real-time PCR method that uses bridged nucleic acid clamping technology to rapidly detect mutations in RAS exons 2-4 and BRAF exon 15. Genomic DNA was extracted from 54 formalin-fixed paraffin-embedded (FFPE) tissue samples obtained from mCRC patients. Among the 54 FFPE samples, BNA Real-time PCR detected 21 RAS mutations (38.9%) and 5 BRAF mutations (9.3%), and the reference assay (KRAS Mutation Detection Kit and MEBGEN™ RASKET KIT) detected 22 RAS mutations (40.7%). The concordance rate of detected RAS mutations between the BNA Real-time PCR assay and the reference assays was 98.2% (53/54). The BNA Real-time PCR assay proved to be a more simple, rapid, and cost-effective method for detecting KRAS and RAS mutations compared with existing assays. These findings suggest that BNA Real-time PCR is a valuable tool for predicting the efficacy of early anti-EGFR therapy in mCRC patients.

Decreased death from gastric cancer by endoscopic screening: association with a population-based cancer registry.

OBJECTIVE: To determine death rates from gastric cancer when using endoscopic screening. MATERIAL AND METHODS: In this historical cohort study comprising 11,763 participants aged from 40 to 75 years without gastric disorders between 1990 and 1992, 2192 were examined by gastric endoscopy while 9571 were not examined by endoscopy or X-ray. The relative risk of gastric cancer death was compared between the two groups. RESULTS: When screened with endoscopy, 41 patients were diagnosed with gastric cancer and the ratio of early cancer was 78%. On matching the population-based cancer registry (the Fukui Cancer Registry), 63 patients in the examined group were diagnosed with gastric cancer within 10 years after the initial screening including the above 41 patients. In the non-examined group, 147 patients were diagnosed with gastric cancer in the same period. In the examined and non-examined groups, 5 and 63 patients, respectively, died from gastric cancer. The relative risk for gastric cancer death in the examined group was 0.3465 (95% CI: 0.1396-0.8605) when compared with the non-examined group. For male patients, the relative risk was 0.2174 (95% CI: 0.0676-0.6992). CONCLUSIONS: The death rate from gastric cancer decreased when endoscopic screening was used. Endoscopy is recommended as a population-based screening method for gastric cancer in regions or countries where mortality from this disease is high.

IgG4-related inflammatory abdominal aortic aneurysm associated with autoimmune pancreatitis.

An association between autoimmune pancreatitis (AIP) and inflammatory abdominal aortic aneurysm (AAA) has never been reported. Reported herein is a case of IgG4-related inflammatory AAA accompanying metachronous AIP. A 77-year-old man presented with malaise and intermittent lower abdominal pain. Radiological examination showed inflammatory AAA and right hydronephrosis caused by retroperitoneal fibrosis. Surgical correction of the AAA was performed, but high levels of systemic inflammatory markers persisted. Four months after surgery, the patient presented with epigastric pain, backache, and jaundice. His serum IgG4 concentration was high (571 mg/mL), and he was diagnosed with AIP, based on clinical and radiological findings. Corticosteroid therapy resulted in improvement of the clinical findings and lowered his serum IgG4 levels. Subsequent histological examination of a specimen from the aortic wall showed irregular proliferation of fibroblastic and myofibroblastic cells, severe lymphoplasmacytic infiltration, and obliterative phlebitis in the adventitia. Furthermore, on immunohistochemistry many plasma cells within the lesion were found to be positive for IgG4. These findings suggest that inflammatory AAA has a pathological process similar to that of AIP, and that some cases of inflammatory AAA and retroperitoneal fibrosis may be aortic and periaortic lesions of an IgG4-related sclerosing disease.