Neurogenic intermittent claudication caused by vasculitis in the cauda equina: an autopsy case report.

PURPOSE: Intermittent claudication (IC) refers to leg pain that is induced by walking and relieved by rest. Neurogenic IC is usually associated with lumbar canal stenosis (LCS). We present rare findings from an autopsied patient who had neurogenic IC caused by vasculitis in the cauda equina. METHODS: We performed antemortem neurological and electrophysiological assessments, sural nerve biopsy, and post-mortem examination of the spinal cord and brain. RESULTS: A 61-year-old man noted sudden-onset leg pain that was not associated with any traumatic trigger. His leg pain consistently appeared when the patient walked and quickly faded on stopping. Spine surgery and cardiovascular departments both made a diagnosis of IC. However, magnetic resonance imaging (MRI) did not show LCS, and all ankle-brachial pressure indices were normal. He subsequently developed diffuse muscle weakness of the legs a month after disease onset. Myeloperoxidase antineutrophil cytoplasmic autoantibody was seropositive (140 IU/mL), and a sural nerve biopsy revealed axonal injury and angiitis. MRI showed multiple cerebral infarctions. He was diagnosed with microscopic polyangiitis (MPA) and underwent corticosteroid therapy. He died from complications two months after the onset. A post-mortem study revealed vasculitis in the subarachnoid space of the cauda equina, spinal cord, and brain parenchyma. The cauda equina showed a combined loss of small and large axonal fibres. The lumbar cord displayed central chromatolysis of the lower motor neurons. CONCLUSION: MPA is a rare cause of neurogenic IC when the symptom is acute and multimodal. Small-vessel vasculitis affecting the cauda equina may underlie MPA-associated IC.

Clinical features and risk factors for appendiceal diverticulitis: a comparative study with acute appendicitis.

PURPOSE: Despite their similar clinical characteristics, appendiceal diverticulitis (AD) and acute appendicitis (AA) are pathologically distinct. This study compared the clinical features of AD and AA and identified relevant risk factors. METHODS: Patients who underwent appendectomy with a preoperative diagnosis of either AD or AA were categorized based on histopathological findings. The two groups were compared in terms of various clinical factors. RESULTS: Among the 854 patients included in the study, a histopathological evaluation revealed 49 and 805 cases of AD and AA, respectively. A univariate analysis demonstrated that AD was more prevalent than AA among older, taller, and heavier males. A multivariate analysis revealed that male sex, a white blood cell (WBC) count < 13.5 × 103/µL, an eosinophil count ≥ 0.4%, and a mean corpuscular volume (MCV) ≥ 91.6 fL were significant factors differentiating AD from AA. In addition, pathological AD emerged as an independent risk factor for abscess and/or perforation. CONCLUSIONS: AD was associated with an older age, robust physique, and significant risk of abscess and/or perforation despite a low WBC count. In addition to imaging modalities, the preoperative factors of male sex, a WBC count < 13.5 × 103/µL, an eosinophil count ≥ 0.4%, and a MCV ≥ 91.6 fL may be useful for distinguishing AD from AA.

Neurolymphomatosis in follicular lymphoma: an autopsy case report.

Neurolymphomatosis is a neurological manifestation of lymphoma that involves the cranial or spinal peripheral nerves, nerve roots, and plexus with direct invasion of neoplastic cells. Neurolymphomatosis is rare among patients with low-grade lymphoma. We report an autopsied case of neurolymphomatosis that arose from follicular lymphoma. A 49-year-old woman who presented with pain of her neck and shoulder and numbness of her chin. Computed tomography revealed enlarged lymph nodes in her whole body, and biopsy from the axillary lymph node revealed grade 2 follicular lymphoma. Although the patient underwent chemotherapy, she gradually developed muscle weakness in the upper limbs and sensory disturbances of the trunk and limbs. 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) revealed increased tracer uptake of the cervical nerve roots. Repeated FDG-PET after additional therapy revealed progression of disease within the nerve roots and brachial plexus, whereas gadolinium-contrast magnetic resonance imaging (MRI) showed weak enhancement of the cervical nerve roots without formation of mass lesions. She died after a total disease duration of 12 months. Postmortem observations revealed invasion of lymphoma cells into the cervical nerve roots, dorsal root ganglia, and subarachnoid spaces of the spinal cord. Neurolymphomatosis was prominent at the segments of C6-Th2. Combined loss of axons and myelin sheaths was observed in the cervical nerve roots and posterior columns. Lymphoma cells also invaded the cranial nerves. The subarachnoid and perivascular spaces of the brain demonstrated focal invasion of the lymphoma. Mass lesions were not observed in the central nervous system. The lymphoma cells did not show histological transformation to higher grades, and the density of the centroblasts remained at grade 2. Our report clarifies that low-grade follicular lymphoma can manifest as neurolymphomatosis and central nervous system invasion in the absence of transformation toward higher histological grades. FDG-PET may be more sensitive to non-mass-forming lesions, including neurolymphomatosis, than gadolinium-contrast MRI.

Chronological Changes in Appendiceal Pathology Among Patients Who Underwent Appendectomy for Suspected Acute Appendicitis.

BACKGROUND: Given recent advances in imaging and the development of diagnostic parameters, the rate of unnecessary appendectomy (i.e., negative appendectomy) has been decreasing. However, the incidence of acute appendicitis (AA) in elderly patients is rising due to the aging of society. We aimed to identify chronological changes in demographics and appendiceal pathology among patients who underwent appendectomy for suspected AA. METHODS: Data from 881 patients who underwent appendectomy for suspected AA between January 2006 and December 2017 were analyzed. The final diagnosis was based on intraoperative findings, pathological reports, and clinical course. Negative appendectomy was defined as the absence of appendiceal diseases including inflammation, fibrosis, and neoplasm. We compared demographics and appendiceal pathology between early (2006-2011) and late study phases (2012-2017). RESULTS: The mean age of patients with pathologically proven AA (n = 761) was significantly greater in the late phase than in the early phase (38.6 ± 19.8 years vs. 44.0 ± 20.3 years, p = 0.0002), and the ratio of patients with AA aged ≧ 75 years was also increased (from 5.6 to 8.6%, p = 0.1120). The incidences of complicated appendicitis (defined as perforated or gangrenous appendicitis) and appendiceal diverticulitis (AD) were increased in the late phase compared to those in the early phase (61.3% vs. 77.2% and 3.7% vs. 6.6%, respectively). The negative appendectomy rate was significantly reduced in the late phase compared to that in the early phase (10.0% vs. 2.5%, p < 0.0001). CONCLUSIONS: During a 12-year period, the mean age of patients with AA and the incidences of complicated appendicitis and AD increased, whereas the negative appendectomy rate decreased.

IgG4 plasma cell myeloma: Clinicopathological characteristics and diagnosis.

Plasma cell myeloma (PCM) is usually associated with the presence of M-protein in the serum and urine of patients, and about half of the PCM cases exhibit the IgG M-protein and increased gamma-globulin fraction on membrane electrophoresis. The IgG4 subclass is located in the beta-2 fraction on membrane electrophoresis. The aim of this study was to develop a method to evaluate IgG4-producing PCM (IgG4-PCM) and its clinicopathological characteristics. We found three cases of IgG4-PCM among 80 cases of IgG-producing PCM by membrane electrophoresis, which were confirmed by IgG4 immunostaining. None of the cases had a clinical history of IgG4-related disease, although they exhibited high levels of serum IgG4. A bone marrow aspiration specimen had an increased number of plasma cells with a relatively mature morphology. No cases exhibited lymphoplasmacytic inflammation, obliterative phlebitis or fibrosis. Immunohistochemistry revealed that tumor cells expressed CD138 and IgG4 and showed monoclonal expression of kappa. We revealed that IgG4-PCM might not be associated with IgG4-related disease and that the detection of M-protein with beta-globulin fraction by electrophoresis may be useful for screening IgG4-PCM.

[Classic Hodgkin lymphoma developing early after treatment of follicular lymphoma].

There are few reports of a patient presenting with combined follicular lymphoma (FL) and classical Hodgkin lymphoma (cHL). A 37-year-old Japanese man was diagnosed with FL with generalized lymphadenopathy and treated with R-CHOP. Four months later, he presented with fever, elevated lactic acid dehydrogenase (LDH), and pancytopenia. Consequently, he was diagnosed with cHL in the bone marrow. Identical clonality of FL and cHL tumor cells suggested identical immunoglobulin heavy chain gene rearrangements. He was treated with salvage chemotherapy and high-dose chemotherapy with autologous hematopoietic stem cell transformation (HDT-ASCT), which has led to complete remission and no recurrence for more than two years after transplantation. Our case suggests that HDT-ASCT may be an effective treatment for this rare clinical condition.

Mesenchymal-epithelial transition gene amplification and protein overexpression in stage IV pulmonary adenocarcinoma.

BACKGROUND: In non-small cell lung cancer (NSCLC), MET gene copy number gain, including gene amplification and chromosome 7 polysomy, is reportedly associated with patient prognosis. Although relationship between MET copy number gain and poor prognosis has been suggested in surgically resected non-small cell lung cancer, the clinical significance of MET copy number gain and protein overexpression in patients with advanced unresectable tumor is unclear. METHODS: We assessed MET copy number gain and protein expression using fluorescence in situ hybridization and immunohistochemistry in 88 patients with clinical stage IV pulmonary adenocarcinoma receiving chemotherapy, immunotherapy or palliative care. RESULTS: We found MET amplification, polysomy 7 and high MET protein expression in 10.2, 18.2 and 62.5% of 88 cases, respectively. Gene amplification and high protein expression were not significantly associated. A univariate analysis showed that MET amplification-positive patients had increased overall survival (HR 0.335, 95% CI: 0.119-0.945; P = 0.0388). Although it was not statistically significant in the multivariate analysis of the whole cohort, with the removal of patients who did not receive any treatment other than palliative care, MET amplification independently improved the overall survival (HR 0.178, 95% CI: 0.041-0.770; P = 0.0209). Chromosome 7 polysomy and high MET protein expression did not affect the overall survival. CONCLUSIONS: Although MET amplification-positive tumor is considered aggressive, our results suggest that it has a more favorable prognosis than amplification-negative cases in stage IV pulmonary adenocarcinoma with medical treatment.

Macrophage-mediated complications after stem cell transplantation.

Complications after hematopoietic stem cell transplantation (HSCT) especially graft versus host disease (GVHD) are serious events and the keys to success of HSCT. Pathological diagnosis of complications is critical but sometimes not definite in GVHD diagnosis. In this review, we focus on the role of macrophages in HSCT complications. In the early period after HSCT, residual recipient macrophages have important roles for engraftment and rejection. Hemophagocytosis is the main feature of activated recipient macrophages. Skin lesions after HSCT are usually skin GVHD but mimicking histology of interface dermatitis is hardly differentiated. Macrophages and lymphocytes of these lesions were studied and increased numbers of macrophages were significantly associated with overall survival of HSCT. It could be suggested macrophages were good predictive markers for skin GVHD-like lesions. Intestinal type transplantation-associated microangiopathy (i-TAM) is an independent pathogenesis from GVHD with serious prognosis. Activated macrophages in these lesions are important and key to the pathogenesis of i-TAM. These activated macrophages are predominantly residual recipient tissue-resident macrophages. Cryptogenic organizing pneumonitis is a lung complication around day 100 after HSCT caused by activated alveolar macrophages. They are donor-derived tissue-resident macrophages. Residual recipient and donor-derived macrophages work in different ways in HSCT complications.

Culture-based bacterial evaluation of the appendix lumen in patients with and without acute appendicitis.

PURPOSE: Controversy exists over whether bacterial flora within the appendix differs between patients with and without appendicitis. To examine these potential differences, we cultured the appendiceal luminal microbiota of patients with and without acute appendicitis, and identified the bacterial species therein. METHODS: Fifty-seven patients with acute appendicitis and 37 patients without acute appendicitis who underwent curative resection of colorectal cancer and prophylactic appendectomies (control group) were included. Appendicitis patients were classified into the phlegmonous group or the gangrenous appendicitis group histopathologically. There was no patient with perforated appendicitis. Aerobic isolates were identified using standard identification schemata, and anaerobic isolates were identified according to the Japanese guidelines. RESULTS: There were no significant differences among the three groups in the median number aerobe species present per patient. However, the median number anaerobe species in the gangrenous appendicitis group was significantly higher than that of the control group and the phlegmonous appendicitis group. In addition, the incidence of patients with Bacillus species, Fusobacterium nucleatum, and Bilophila wadsworthia increased as the disease progressed from phlegmonous to gangrenous appendicitis. CONCLUSION: The present results suggest that increased diversity of anaerobes and the translocation of Bacillus species, F. nucleatum, and B. wadsworthia are associated with the progression of acute appendicitis.

A case of undifferentiated carcinoma of the pancreas mimicking main-duct intraductal papillary mucinous neoplasm (IPMN).

We report here a rare case of undifferentiated carcinoma of the pancreas mimicking main-duct intraductal papillary mucinous neoplasm. In an 80-year-old woman, an approximately 8-mm papillary mass was incidentally detected at the downstream edge of a dilatated main pancreatic duct lumen on CT and MRI. Main pancreatic duct dilatation in the pancreatic body and tail and parenchymal atrophy were observed in the upstream of the mass. Histopathologically, the tumor protruded into the downstream edge of the dilatated main pancreatic duct lumen in the pancreatic body. The tumor cells had highly atypical nuclei and abundant polymorphic structures, and showed positive staining for granulocyte colony-stimulating factor, which led to the diagnosis of undifferentiated carcinoma. A total of 13 cases of undifferentiated carcinoma with intraductal tumor growth have been reported to date. The case report by Bergmann et al. has been the smallest in histopathological specimen, and the present case is the smallest in size detected by radiological images. Since early undifferentiated carcinoma of the pancreas can resemble those of main-duct intraductal papillary mucinous neoplasm in cross-sectional images, we have to consider undifferentiated carcinoma in the differential diagnosis of the solitary and papillary mass with low contrast enhancement in early phase in the main pancreatic duct.

Pulmonary inflammatory myofibroblastic tumor harboring EML4-ALK fusion gene.

Inflammatory myofibroblastic tumor is a rare tumor deriving from mesenchymal tissue. Approximately 50% of inflammatory myofibroblastic tumors harbor an anaplastic lymphoma kinase fusion gene. Pulmonary inflammatory myofibroblastic tumors harboring tropomyosin3-anaplastic lymphoma kinase or protein tyrosine phosphatase receptor-type F polypeptide-interacting protein-binding protein 1-anaplastic lymphoma kinase have been reported previously. However, it has not been reported that inflammatory myofibroblastic tumors harbor echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion gene which is considered to be very specific to lung cancers. A few tumors harboring echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion gene other than lung cancers have been reported and the tumors were all carcinomas. A 67-year-old man had been followed up for a benign tumor for approximately 3 years before the tumor demonstrated malignant transformation. Lobectomy and autopsy revealed that an inflammatory myofibroblastic tumor harboring echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion gene had transformed into an undifferentiated sarcoma. This case suggests that echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase fusion is an oncogenic event in not only carcinomas but also sarcomas originating from stromal cells.

ß-catenin mutation in ovarian solid pseudopapillary neoplasm.

Primaly solid pseudopapillary neoplasm (SPN) of the ovary is a rare tumor; recently 6 cases have been reported. Its pathogenesis, however, remains largely unclear. We report an additional case of primary ovarian SPN of an 18-year-old girl. The aim of this study is to define the difference between pancreatic and ovarian SPN by histological and molecular examination. Microscopically the tumor predominantly showed a solid pattern and focally a pseudopapillary pattern. The tumor cells showed two patterns of abundant eosinophilic cytoplasm and intracytoplasmic vacuoles. Immunohistochemistry of the tumor was positive for ß-catenin (nuclear and cytoplasmic reactivity), α1-antitrypsin, vimentin, CD56, synaptophysin (focal weak), CD10. Mutation analyses revealed a point mutation, c.110C >T, in exon 3 of the the ß-catenin gene (CTNNB1), which causes the replacement of serine with phenylalanine at codon 37. A Ser37 point mutation is known to be one of the oncogenic somatic mutations in pancreatic SPN and the major oncogenic ß-catenin mutation. Ovarian SPN of our case was similar to pancreatic SPN histologicaly and had the same genomic characteristics. We expected that both ovarian and pancreatic SPNs shared the same oncogenesis related to Wnt/ß-catenin pathway for tumorgenesis.

[Granulosa cell tumor of the ovary - analysis of 15 cases in a single institution].

The best treatment for recurrent granulosa cell tumor(GCT)is considered to be surgical resection, because the effects of chemotherapy or radiation on GCT are obscure. The common site of recurrence is the pelvic cavity, including the surface of the liver and intestine as tumor-dissemination-patterns. Between June 1988 and June 2011, we treated 15 patients with GCT at our hospital. The median follow-up time was 56(22-286)months. Ten patients were stage I, 3 were stage II, and 2 were stage III. No patients had residual lesions at the primary surgery area. Six patients have recurred, and the median disease free survival(DFS)was 85(15-128)months. Six patients had relapses in the pelvic cavity, 2 in the retroperitneal lymph nodes, and 1 in the upper abdomen. Two patients relapsed more than twice; however, the rapid detection of recurrence and surgical resection have kept all patients alive. Thirteen patients have no evidence of disease(NED), 2 are alive with disease(AWD), and no one has died of the disease(DOD). We suggest that maximal debulking surgery to achieve complete cytoreduction of recurrent GCT is the most important treatment for prolonging survival.

Comprehensive circulating microRNA profile as a supersensitive biomarker for early-stage lung cancer screening.

PURPOSE:  Less-invasive early diagnosis of lung cancer is essential for improving patient survival rates. The purpose of this study is to demonstrate that serum comprehensive miRNA profile is high sensitive biomarker to early-stage lung cancer in direct comparison to the conventional blood biomarker using next-generation sequencing (NGS) technology combined with automated machine learning (AutoML). METHODS: We first evaluated the reproducibility of our measurement system using Pearson's correlation coefficients between samples derived from a single pooled RNA sample. To generate comprehensive miRNA profile, we performed NGS analysis of miRNAs in 262 serum samples. Among the discovery set (57 patients with lung cancer and 57 healthy controls), 1123 miRNA-based diagnostic models for lung cancer detection were constructed and screened using AutoML technology. The diagnostic faculty of the best performance model was evaluated by inspecting the validation samples (74 patients with lung cancer and 74 healthy controls). RESULTS: The Pearson's correlation coefficients between samples derived from the pooled RNA sample ≥ 0.98. In the validation analysis, the best model showed a high AUC score (0.98) and a high sensitivity for early stage lung cancer (85.7%, n = 28). Furthermore, in comparison to carcinoembryonic antigen (CEA), a conventional blood biomarker for adenocarcinoma, the miRNA-based model showed higher sensitivity for early-stage lung adenocarcinoma (CEA, 27.8%, n = 18; miRNA-based model, 77.8%, n = 18). CONCLUSION: The miRNA-based diagnostic model showed a high sensitivity for lung cancer, including early-stage disease. Our study provides the experimental evidence that serum comprehensive miRNA profile can be a highly sensitive blood biomarker for early-stage lung cancer.

Plasmablastic lymphoma of the stomach in an HIV-negative patient.

Plasmablastic lymphoma (PBL) is a rare B-cell neoplasm with an aggressive clinical behavior that predominantly occurs in the oral cavity of human immunodeficiency virus (HIV)-positive patients. However, it has recently been recognized that PBLs can also affect individuals without HIV infection, and suggested that these neoplasms show different clinicopathological characteristics between HIV-positive and -negative patients. Herein we describe a case of gastric PBL in a female HIV-negative patient. The tumor was composed of a diffuse and cohesive proliferation of large neoplastic cells, which resembled immunoblasts or plasmablasts with a starry sky appearance. Immunophenotypically, the neoplastic cells were diffusely positive for CD138, MUM1, IgM, and BOB-1, and negative for CK, LCA, CD3, CD20, CD79a, Pax5, kappa, lambda, CD30, ALK, S-100, HMB-45, MPO, and HHV-8. The MIB-1 index was nearly 100%. Epstein-Barr virus-encoded RNA in situ hybridization was negative. A monoclonal immunoglobulin heavy chain gene rearrangement was detected in polymerase chain reaction (PCR) and heteroduplex analyses. A combination of PCR-based analysis of immunoglobulin gene rearrangement and immunohistochemistry can be useful to substantiate the diagnosis by utilizing routine paraffin-embedded tissue sections, because PBL in the setting of extra-oral localization and immunocompetence is a diagnostic challenge, given its rarity, morphology, and absence of CD20 expression.

SMARCA4-deficient rectal carcinoma with a sarcomatoid component: a case report.

A new classification of SMARCA4-deficient tumors was proposed recently for thoracic malignancies, and the tumors have some histopathological characteristics similar to those of carcinosarcoma. We encountered a case of SMARCA4-deficient rectal carcinoma with a sarcomatoid component. A 46-year-old man presented to our hospital with a prolapsing anal mass. Colonoscopy revealed an irregular, nodular, and elevated lesion in the rectum, and the biopsy revealed a moderately differentiated adenocarcinoma. Abdominoperineal resection of the rectum was performed. A macroscopic image of the resected specimen showed a complex tumor 3.5 cm × 3 cm in size with a papillary protrusion and an irregular ulcerative lesion. Histopathological examination revealed that the tumor was composed of moderately/poorly differentiated adenocarcinoma and atypical spindle cells. The adenocarcinoma component was positive for epithelial markers (AE1/AE3 and carcinoembryonic antigen) and showed deletion of SMARCA2 and SMARCA4, while the spindle cells expressed mesenchymal markers (α-smooth muscle actin and vimentin). The pathological diagnosis was poorly differentiated adenocarcinoma with a sarcomatoid component, pT3N2bM0, stage IIIc. Although our case had histological characteristics of carcinosarcoma, immunostaining revealed a deficiency of SMARCA4. This case presented a SMARCA4-deficient colorectal carcinoma with a sarcomatoid component, which was histopathologically similar to carcinosarcoma.

Portal vein leiomyosarcoma invading the pancreatic head.

We encountered a rare case of a pancreatic head tumor protruding into the portal vein, later diagnosed histopathologically as primary leiomyosarcoma of the portal vein. A 59-year-old woman visited our hospital because of an elevated amylase level during a medical checkup. Computed tomography showed a moderately contrasted, well-defined mass of 35-mm diameter in the pancreatic head with protrusion into the portal vein. Endoscopic ultrasonography revealed a well-defined and hypoechoic mass. Fluorodeoxyglucose-positron emission tomography showed a high accumulation of fluorodeoxyglucose in the pancreas head. We performed a subtotal stomach-preserving pancreaticoduodenectomy with portal vein resection. Gross findings of the fixed specimen showed a white solid, multinodular mass in the pancreatic parenchyma with protrusion into the portal vein. Histopathological examination showed proliferation of spindle-shaped eosinophilic cells with intricate bundle-like growth, indicating leiomyosarcoma. Examining the tumor location and invasion suggested portal vein as the origin. Although portal vein primary leiomyosarcoma is rare, leiomyosarcoma should be considered as a differential diagnosis in pancreatic head tumors with protrusion into the portal vein. Precise macroscopic and histopathological examinations can help determine the definitive diagnosis and origin of leiomyosarcoma.

Long-term survivor who underwent surgical resections of repeated peritoneal oligometastases from colon cancer : a rare case report.

A 74-year-old woman underwent right hemicolectomy and partial ileal resection for ascending colon cancer with synchronous peritoneal metastasis. Histopathological examination showed moderately differentiated adenocarcinoma with mucinous component, pT4b N3 M1, and Stage IV. Postoperative chemotherapy comprising 36 courses of mFOLFOX6 with bevacizumab was administered. Twenty-two months after the surgery, computed tomography (CT) revealed a 20 mm nodular lesion adjacent to the gastric wall, and laparoscopic resection of the nodule was performed. Thirty-nine months after the second surgery, CT showed a 24 mm nodular lesion involving the liver parenchyma, and partial hepatectomy involving the nodule was performed. Histopathological examination of the nodules resected by the second and third surgeries showed the same features as the primary ascending colon cancer. The nodules were diagnosed as metachronous peritoneal metastases. The patient followed up without chemotherapy after the second and third surgery, showed no recurrence for 26 months after the third surgery. Fortunately, more than 7 years have passed since the primary tumor resection. Hence, surgical resection for synchronous and repeated metachronous peritoneal oligometastases from colon cancer can offer long-term survival. J. Med. Invest. 69 : 302-307, August, 2022.

Diagnosis and clinical implication of collision gastric adenocarcinomas: a case report.

BACKGROUND: Collision tumors are a subtype of simultaneous tumors wherein two unrelated tumors collide or infiltrate each other. Collision gastric adenocarcinomas (CGA) are rare and difficult to diagnose, and their clinical implications remain unclear. Herein, we aimed to reveal diagnostic methods for CGA and provide insight into its implications. CASE PRESENTATION: Among 1041 cases of gastric cancers (GCs) resected between 2008 and 2018, we included cases of confirmed CGA. Patients' backgrounds, preoperative endoscopy findings, macroscopic imaging findings, and histopathology findings [including immunostaining for CK 7, MUC2, and mismatch repair (MMR) proteins] were investigated. The incidence of CGA was 0.5%: 5 of 81 cases having simultaneous multiple GCs. Tumors were mainly in the distal stomach. The CGA in two cases was between early cancers, in two cases was between early and advanced cancers, and in one case was between advanced cancers. There were three cases of collision between differentiated and undifferentiated types and two cases between differentiated types. Immunostaining with CK7 and MUC2 was useful for diagnosing collision tumor when the histology was similar to each other. Among ten GCs comprising CGA, nine tumors (90%) exhibited deficient MMR proteins, suggesting high microsatellite instability (MSI). CONCLUSIONS: CGA is rare and usually found in the distal stomach. Close observation of shape, optimal dissection, and detailed pathological examination, including immunostaining, facilitated diagnosis. CGAs may have high MSI potential.

Superficial spreading type of early gastric cancer with diagnostic difficulty and positive surgical margin: a case report.

An 83-year-old man visited our hospital because of difficulty swallowing. Gastroscopy revealed multiple ulcers and a reddish depression in the lesser curvature of the middle stomach. The initial biopsy showed regenerative atypia, so a gastroscopy was repeated every 3 months thereafter because of suspected malignancy. A biopsy performed 12 months after the initial gastroscopy revealed a well-differentiated adenocarcinoma. After determination of the planned oral resection line by two negative biopsies, laparoscopic distal gastrectomy was performed. The resected specimen showed a 0 - IIa + IIc lesion composed of well-to-moderately differentiated tubular adenocarcinoma, including hand-shaking-type gastric cancer. The oral resection margin was positive due to widespread mucosal extension; therefore, an additional total gastrectomy was needed. Cases of well-differentiated adenocarcinoma and its superficial extension may be difficult to diagnose via endoscopy and biopsy.