Alkali control of high-grade metamorphism and granitization

We review petrologic observations of reaction textures from high-grade rocks that suggest the passage of fluids with variable alkali activities. Development of these reaction textures is accompanied by regular compositional variations in plagioclase, pyroxenes, biotite, amphibole and garnet. The textures are interpreted in terms of exchange and net-transfer reactions controlled by the K and Na activities in the fluids. On the regional scale, these reactions operate in granitized, charnockitized, syenitized etc. shear zones within high-grade complexes. Thermodynamic calculations in simple chemical systems show that changes in mineral assemblages, including the transition from the hydrous to the anhydrous ones, may occur at constant pressure and temperature due only to variations in the H2O and the alkali activities. A simple procedure for estimating the activity of the two major alkali oxides, K2O and Na2O, is imple- mented in the TWQ software. Examples of calculations are presented for well-documented dehydration zones from South Africa, southern India, and Sri Lanka. The calculations have revealed two end-member regimes of alkalis during specific metamorphic processes： rock buffered, which is characteristic for the precursor rocks containing two feldspars, and fluid-buffered for the precursor rocks without K-feldspar. The observed reaction textures and the results of thermodynamic modeling are compared with the results of available experimental studies on the interaction of the alkali chloride and carbonate-bearing fluids with metamorphic rocks at mid-crustal conditions. The experiments show the complex effect of alkali activities in the fluid phase on the mineral assemblages. Both thermodynamic calculations and experiments closely reproduce paragenetic relations theoretically predicted by D.S. Korzhinskii in the 1940s.

High-grade pancreatic intraepithelial neoplasia diagnosed based on changes in magnetic resonance cholangiopancreatography findings:A case report

BACKGROUND High-grade pancreatic intraepithelial neoplasia(PanIN)exhibits no mass and is not detected by any examination modalities.However,it can be diagnosed by pancreatic juice cytology from indirect findings.Most previous cases were diagnosed based on findings of a focal stricture of the main pancreatic duct(MPD)and caudal MPD dilatation and subsequent pancreatic juice cytology using endoscopic retrograde cholangiopancreatography(ERCP).We experienced a case of high-grade PanIN with an unclear MPD over a 20-mm range,but without caudal MPD dilatation on magnetic resonance cholangiopancreatography(MRCP).CASE SUMMARY A 60-year-old female patient underwent computed tomography for a follow-up of uterine cancer post-excision,which revealed pancreatic cysts.MRCP revealed an unclear MPD of the pancreatic body at a 20-mm length without caudal MPD dilatation.Thus,course observation was performed.After 24 mo,MRCP revealed an increased caudal MPD caliber and a larger pancreatic cyst.We performed ERCP and detected atypical cells suspected of adenocarcinoma by serial pancreatic juice aspiration cytology examination.We performed a distal pancreatectomy and obtained a histopathological diagnosis of high-grade PanIN.Pancreatic parenchyma invasion was not observed,and curative resection was achieved.CONCLUSION High-grade Pan-IN may cause MPD narrowing in a long range without caudal MPD dilatation.

Management of retroperitoneal high-grade serous carcinoma of unknown origin:A case report

BACKGROUND Retroperitoneal high-grade serous carcinoma(HGSC)of unknown origin is a sporadic tumor that can originate from ovarian cancer.Herein,we report the case of a woman with retroperitoneal HGSC of unknown origin and describe how she was diagnosed and treated.CASE SUMMARY A 71-year-old female presented with the tumor marker CA125 elevated to 1041.9 U/mL upon a regular health examination.Computed tomography revealed retroperitoneal lymph node enlargement.Subsequently,positron emission tomography scanning revealed lesions with increased F-18 fluorodeoxyglucose uptake at the nodes.As a result,she underwent laparoscopic lymph node resection,and pathology revealed metastatic adenocarcinoma with CK7(+),PAX8(+),WT1(+),PR(-),and p53 mutational loss of expression,indicating that the origin may be from the adnexa.The patient was admitted to our ward and underwent laparoscopic staging;however,the pathological results were negative.Under the suspicion of retroperitoneal HGSC of unknown origin,chemotherapy and targeted therapy were initiated.Tumor marker levels decreased after treatment.CONCLUSION We present a case of HGSC of unknown origin managed using retroperitoneal lymphadenectomy,staging surgery,chemotherapy,and targeted therapy.

High-grade serous carcinoma of the fallopian tube in a young woman with chromosomal 4q abnormality:A case report

BACKGROUND Few studies have reported an association between an increased risk of acquiring cancers and survival in patients with 4q deletion syndrome.This study presents a rare association between chromosome 4q abnormalities and fallopian tube highgrade serous carcinoma(HGSC)in a young woman.CASE SUMMARY A 35-year-old woman presented with acute dull abdominal pain and a known chromosomal abnormality involving 4q13.3 duplication and 4q23q24 deletion.Upon arrival at the emergency room,her abdomen appeared ovoid and distended with palpable shifting dullness.Ascites were identified through abdominal ultrasound,and computed tomography revealed an omentum cake and an enlarged bilateral adnexa.Blood tests showed elevated CA-125 levels.Paracentesis was conducted,and immunohistochemistry indicated that the cancer cells favored an ovarian origin,making us suspect ovarian cancer.The patient underwent debulking surgery,which led to a diagnosis of stage IIIC HGSC of the fallopian tube.Subsequently,the patient received adjuvant chemotherapy with carboplatin and paclitaxel,resulting in stable current condition.CONCLUSION This study demonstrates a rare correlation between a chromosome 4q abnormality and HGSC.UBE2D3 may affect crucial cancer-related pathways,including P53,BRCA,cyclin D,and tyrosine kinase receptors,thereby possibly contributing to cancer development.In addition,ADH1 and DDIT4 may be potential influencers of both carcinogenic and therapeutic responses.

Transformation of marginal zone lymphoma into high-grade B-cell lymphoma expressing terminal deoxynucleotidyl transferase:A case report

BACKGROUND High-grade B-cell lymphoma(HGBL)is an unusual malignancy that includes myelocytomatosis viral oncogene(MYC),B-cell lymphoma-2(BCL-2),and/or BCL-6 rearrangements,termed double-hit or triple-hit lymphomas,and HGBL-not otherwise specific(HGBL-NOS),which are morphologically characteristic of HGBL but lack MYC,BCL-2,or BCL-6 rearrangements.HGBL is partially transformed by follicular lymphoma and other indolent lymphoma,with few cases of marginal zone lymphoma(MZL)transformation.HGBL often has a poor prognosis and intensive therapy is currently mainly advocated,but there is no good treatment for these patients who cannot tolerate chemotherapy.CASE SUMMARY We reported a case of MZL transformed into HGBL-NOS with TP53 mutation and terminal deoxynucleotidyl transferase expression.Gene analysis revealed the gene expression profile was identical in the pre-and post-transformed tissues,suggesting that the two diseases are homologous,not secondary tumors.The chemotherapy was ineffective and the side effect was severe,so we tried combination therapy including venetoclax and obinutuzumab.The patient tolerated treatment well,and reached partial response.The patient had recurrence of hepatocellular carcinoma and died of multifunctional organ failure.He survived for 12 months after diagnosis.CONCLUSION Venetoclax combined with obinutuzumab might improve the survival in some HGBL patients,who are unsuitable for chemotherapy.

A Problem of High-Grade Polymetamorphism

A problem of evolution of high-grade polymeta- morphic terrain appeared in last decades:in worldwide complexes the identification of true stages of polymetamorphism encounters a problem of zircon zoning(or garnet etc.)that is the function of fluid activity and therefore the newly formed zone can not always be recorded.Structural geology allows discriminating between different stages of metamor-

Comparison of biological behavior of lacrimal gland adenoid cystic carcinoma with high-grade transformation cells

AIM:To evaluate the differences between human lacrimal gland adenoid cystic carcinoma with high-grade transformation(LACC-HGT)primar y cells cultured by high-grade transformation tissue and non-high-grade transformation(non-HGT)primary cells cultured by non-highgrade transformation tissue in proliferation,metastasis,drug susceptibility,and genes.METHODS:LACC-HGT primary cells were established by tissue block culture,and the 4^(th)to 10^(th)generation primary cells were selected as research objects.The cells were preliminarily identified by immunofluorescent staining.The differences between non-HGT and LACC-HGT primary cells in terms of proliferation,metastasis,and drug susceptibility were compared by cell counting kit-8(CCK-8)assay,wound healing,and drug sensitivity experiments.Differentially expressed genes were screened using mRNA array.Gene expression was analyzed using real-time quantitative polymerase chain reaction(RT-qPCR).RESULTS:LACC-HGT primary cells were successfully cultured by tissue block culture.Immunofluorescence staining results showed that cytokeratin(CK)and CK7 expression levels were positive in LACC-HGT primary cells.CCK-8 results showed that the proliferation ability of LACCHGT cells was significantly higher than that of non-HGT cells.Wound healing experiment showed that the migration ability of LACC-HGT cells was significantly higher than that of non-HGT cells.LACC-HGT cells were also less sensitive to cisplatin and paclitaxel than non-HGT cells.Compared with non-HGT cells,9566 differentially expressed genes were found in LACC-HGT primary cells,of which 5162 were upregulated and 4404 were down-regulated.The expression of N-acetylneuraminate pyruvate lyase(NPL),MARVEL domain containing 3(MARVELD3),syntabulin(SYBU),and allograft inflammatory factor 1(AIF1)was higher in LACCHGT cells than in non-HGT cells,whereas that of periostin(POSTN)was lower.CONCLUSION:LACC-HGT primary cells have faster proliferation,stronger migration ability,and poorer sensitivity to chemotherapy drugs than non-HGT primary cells.The expression of mRNAs in non-HGT and LACC-HGT primary cells are significantly different.These features are speculated to be the reasons why high-grade transformation tissues exhibit higher malignant degree and poorer prognosis than their counterparts.

Application of convolutional neural network-based endoscopic imaging in esophageal cancer or high-grade dysplasia: A systematic review and meta-analysis

BACKGROUND Esophageal cancer is the seventh-most common cancer type worldwide,accounting for 5%of death from malignancy.Development of novel diagnostic techniques has facilitated screening,early detection,and improved prognosis.Convolutional neural network(CNN)-based image analysis promises great potential for diagnosing and determining the prognosis of esophageal cancer,enabling even early detection of dysplasia.METHODS PubMed,EMBASE,Web of Science and Cochrane Library databases were searched for articles published up to November 30,2022.We evaluated the diagnostic accuracy of using the CNN model with still image-based analysis and with video-based analysis for esophageal cancer or HGD,as well as for the invasion depth of esophageal cancer.The pooled sensitivity,pooled specificity,positive likelihood ratio(PLR),negative likelihood ratio(NLR),diagnostic odds ratio(DOR)and area under the curve(AUC)were estimated,together with the 95%confidence intervals(CI).A bivariate method and hierarchical summary receiver operating characteristic method were used to calculate the diagnostic test accuracy of the CNN model.Meta-regression and subgroup analyses were used to identify sources of hetero-geneity.RESULTS A total of 28 studies were included in this systematic review and meta-analysis.Using still image-based analysis for the diagnosis of esophageal cancer or HGD provided a pooled sensitivity of 0.95(95%CI:0.92-0.97),pooled specificity of 0.92(0.89-0.94),PLR of 11.5(8.3-16.0),NLR of 0.06(0.04-0.09),DOR of 205(115-365),and AUC of 0.98(0.96-0.99).When video-based analysis was used,a pooled sensitivity of 0.85(0.77-0.91),pooled specificity of 0.73(0.59-0.83),PLR of 3.1(1.9-5.0),NLR of 0.20(0.12-0.34),DOR of 15(6-38)and AUC of 0.87(0.84-0.90)were found.Prediction of invasion depth resulted in a pooled sensitivity of 0.90(0.87-0.92),pooled specificity of 0.83(95%CI:0.76-0.88),PLR of 7.8(1.9-32.0),NLR of 0.10(0.41-0.25),DOR of 118(11-1305),and AUC of 0.95(0.92-0.96).CONCLUSION CNN-based image analysis in diagnosing esophageal cancer and HGD is an excellent diagnostic method with high sensitivity and specificity that merits further investigation in large,multicenter clinical trials.

Metabasic Dyke Swarms in a High-Grade Metamorphic Terrane——A Case Study in the Taipingzhai-Jinchangyu Area,Eastern Hebei Province

Geological and petrological studies indicate that three phases of metabasic dykes are present in theTaipingzhai-Jinchangyu area within the high-grade metamorphic terrane of eastern Hebei. Garnet andhornblende in metabasic dykes of the second and third phases occur separately, forming two mineral aggregateareas gl+cpx+pl±hy and hb+cpx+pl-hy. P_(H_2O) in the rocks appears to be the main factor controlling theformation of the two aggregate areas. Both were formed simultaneously at the same metamorphic temperature. The second-phase basic dykes underwent metamorphism of pyroxene-granulite facies at a temperature ofsome 825C: later the dykes, together with the third-phase basic dykes experienced metamorphism ofamphibole-granulite facies at a temperature of about 750C under pressure of 0.9GPa.

A Case Report: High-Grade Urothelial Carcinoma in the Renal Pelvis with Complete Kidney and Ureter Duplication Featuring Heterologous Differentiation

This report describes a considerably rare case of high-grade urothelial carcinoma of the renal pelvis and ureter,presenting with heterologous differentiation,in a patient with bilateral duplicated kidneys.A 73-year-old male experienced intermittent gross hematuria for 5 months,accompanied by lower back and abdominal pain.Ultrasound and computed tomography scans revealed bilateral renal and ureteral duplication with multiple tumors in the left renal pelvis.A total nephroterectomy and bladder cuff resection were performed on the left two nephrons.Multiple space-occupying lesions were identified in the left renal pelvis and ureter.Histopathological examination showed poorly differentiated and diverse tumor cells,manifesting as sarcomatoid carcinoma,papillary adenocarcinoma,and infiltrating high-grade urothelial carcinoma.The tumor infiltrated the subcutaneous fibrous connective tissue of the renal pelvis and the full thickness of the ureter.Given the rarity of recurrent renal urothelial carcinoma with heterogeneous differentiation,comprehensive imaging and pathological assessments are vital to delineate the nature of the lesion and the direction of tissue pathological heterologous differentiation.These evaluations guide early radical surgical interventions,improving survival rates.

Metamorphic P-T conditions and zircon U-Pb ages of amphibolite in Laojinchang area,southern Jilin Province

The Longgang Block is one of the most important parts of the eastern North China Craton,characterized by extensive Late Neoarchean(~2.5 Ga)granulite facies metamorphism.However,it remains uncertain whether it was influenced by Paleoproterozoic magmatism-metamorphism.The authors provide a comprehensive analysis of amphibolite in Laojinchang area,southern Jilin Province,through petrographic,geochemical,mineralogical,and zircon dating.The main findings are as follows:The mineral assemblage of amphibolite is Hb+Pl+Cpx+Bi+Kf+Q,characteristic of amphibolite facies;zircon U-Pb dating indicates that the metamorphic age of amphibolite is 1834±33 Ma;the amphibolite has geochemical characteristics of calcium alkaline,with depletion of Nb,Ta,Ti and P.The plagioclase in the amphibolite is oligoclase,belonging to acidic plagioclase.It is speculated that the protolith of the amphibolite is diorite;using geothermobarometer,the peak metamorphic P-T conditions of amphibolite are determined to be 536–593℃/3.4–5.0 kbar,and the post-peak conditions are 429–566℃/1.3–3.1 kbar.The above results indicate that the Paleoproterozoic metamorphism has been superimposed on Longgang Block,linked to a new orogenic event on the northern edge of North China Craton.

Structural,^(40)Ar/^(39)Ar Geochronological and Rheological Feature Analysis of the Guoxuepu Shear Zone:Indications for the Jitang Metamorphic Complex in the Northern Lancangjiang Zone

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone.Through structural-lithological mapping,structural analysis and laboratory testing,the composition of the Jitang metamorphic complex was determined.The macro-and microstructural analyses of the ductile detachment shear zone(Guoxuepu ductile shear zone,2–4 km wide)between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top-to-the-southeast.The presence of various deformation features and quartz C-axis electron backscatter diffraction(EBSD)fabric analysis suggests multiple deformation events occurring at different temperatures.The average stress is 25.68 MPa,with the strain rates(έ)ranging from 9.77×10^(−14)s^(−1)to 6.52×10^(−16)s^(−1).The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern.The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88,implying that the shear zone is dominated by simple shear.The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar-39Ar age of 60.09±0.38 Ma.It is suggested that,coeval with the initial Indo–Eurasian collision,the development of strike-slip faults led to a weak and unstable crust,upwelling of lower crust magma,then induced the detachment of the Jitang metamorphic complex in the Eocene.

TWO EPISODES OF MONAZITE CRYSTALLIZATION DURING METAMORPHISM AND CRUSTAL MELTING IN THE EVEREST REGION OF THE NEPALESE HIMALAYA

New monazite U\|Pb geochronological data from the Everest region suggest that 20～25Ma elapsed between the initial India—Asia collision and kyanite\|sillimanite grade metamorphism. Our results indicate a two\|phase metamorphic history, with peak Barrovian metamorphism at (32 2±0 4)Ma and a later high\|temperature, low\|pressure event (620℃, 400MPa) at (22 7±0 2)Ma.. Emplacement and crystallization of the Everest granite subsequently occurred at 20 5～21 3Ma. The monazite crystallization ages that differ by 10Ma are recorded in two structurally adjacent rocks of different lithology, which have the same post collisional p—T history.. Scanning electron microscopy reveals that the younger monazite is elaborately shaped and grew in close association with apatite at grain boundaries and triple junctions, suggesting that growth was stimulated by a change in the fluid regime. The older monazite is euhedral, is not associated with apatite, and is commonly armoured within silicate minerals. During the low\|pressure metamorphic event, the armouring protected the older monazites, and a lack of excess apatite in this sample prevented new growth. Textural relationships suggest that apatite is one of the necessary monazite\|producing reactants, and spots within monazite that are rich in Ca, Fe, Al and Si suggest that allanite acted as a preexisting rare earth element host. We propose a simplified reaction for monazite crystallization based on this evidence.

Metamorphism of the East Sector of the Southern Qinling Orogenic Belt and Its Geological Significance

The east sector of the southern Qinling belt is, lithologically, composed mainly of metapelites, ***qüartzites, marbles and small amount of metabasites and gneisses, whose protoliths are the Silurian, Devonian and less commonly the Sinian and Upper Palaeozoic. They have been subjected at least to two epochs of metamorphism. The early epoch belongs to progressive metamorphism which is centered on high amphibolite-granulite fades in the Fuping area and changed outwards into low amphibolite facies (staurolite-kyanite zone), epidote amphibolite facies (garnet zone) and greenschist facies (chlorite and biotite zones), the metamorphic age of which is about 220–260 Ma. This early-epoch metamorphism belongs to different pressure types: the rocks from greenschist to low amphibolite facies belong to the typical medium-pressure type which shows geothermal gradients of about 17–20 ***C/km and was probably produced by a crustal thickening process related to continental collision, and the high amphibolite-granulite facies belongs to the low-pressure type which shows geothermal gradients of about 25–38 ***C/km and was probably affected by some magmatic heats. Based on the basic characteristics of the P-T paths of the different facies calculated from the garnet zonations, it can be deduced that the metamorphism of medium-pressure facies series took place during an imbricated thickening process, rather than during the uplifting process after thickening. The late-epoch metamorphism belongs to dynamic metamorphism of greenschist facies which is overprinted on the early-epoch metamorphic rocks and is Yanshanian or Himalayan in age, probably related to intracontinental orogeny.

High- and Ultrahigh-pressure Metamorphism and Retrogressive Textures of Gneiss in the Donghai Area——Evidence from gneisses in drillhole ZK2304

In the gneisses from the drillhole ZK2304 of the Donghai area, there have been preserved high- and ultrahigh-pressure metamorphic mineral assemblages, a series of complicated retrogressive textures and relevant metamorphic reactions. In addition to garnet, jadeititic-clinopyroxene and rutile, other peak stage (M2) minerals in some gneisses include phengite, aragonite and coesite or quartz pseudomorphs after coesite. The typical peak-stage mineral assemblages in gneisses are characterized by garnet + jadeitic-clinopyroxene + rutile + coesite, garnet + jadeitic-clinopyroxene + phengite + rutile ± coesite and garnet + jadeitic-clinopyroxene + aragonite + rutile ± coesite. The grossular content (Gro) in garnet is high and may reach 50. 1 mol%. The SiO2 content of phengite ranges from 54.37% to 54.84% with 3.54-3.57 p.f.u. Quartz pseudomorphs after coesite occur as inclusions in garnet.The gneisses of the Donghai area have been subjected to multistage recrystallization and exhibit a closewise P-T evolutional path characterized by the near-isothermal decompression. The inclusion assemblage (Hb+Ep+Bi+Pl+Qz) within garnet and other minerals has recorded a pre-peak stage (Mi) epidote amphibole fades metamorphic event. High- and ultrahigh-pressure peak metamorphism (M2) took place at T=750-860℃ and P>2.7 GPa. The symplectitic assemblages after garnet, jadeitic-clinopyroxene and rutile imply a near-isothermal decompression metamorphism (M3, M4) during the rapid exhumation. Several lines of evidence of petrography and metamorphic reactions indicate that both gneisses and eclogites have experienced ultrahigh-pressure metamorphism in the Donghai area. This research may be of great significance for an in-depth study of the metamorphism and tectonic evolution in the Su-Lu ultrahigh-pressure metamorphic belt.

Eclogites of the Dabie Region: Retrograde Metamorphismand Fluid Evolution

Based upon fluid effects, retrograde metamorphism of eclogites in the Dabieregion can be divided into the fluid-poor, fluid-bearing and fluid-rich stages. The fluid-poor stageis marked by polymorphic inversion, recrystallization and exsolution of solid solutions, and isthought to represent eclogite-facies retrograde environments. The fluid-bearing stage is likely tohave occurred at the late stage of ecologite-facies diaphthorosis and is represented by kyaniteporphyroblasts, rutile, and sodic pyroxene in association with high-pressure hydrous minerals suchas phengite and zoisite (clinozoisite) without significant amount of hydrous minerals such asamphibole, epidote and biotite. The fluid-rich stage might have commenced concomitantly with loweramphibolite-facies diaphthoresis and persisted all the way towards the near-surface environment. Theproduct of this stage is characterized by plentiful hydrous and volatile-bearing phases.The dissemination-type rutile mineralizations in eclogites might have formed by preferentialshearing-induced pressure solution of gangue minerals at the fluid-bearing stage. The accompanyingvein rutile was precipitated from fluids of this stage after local transport and concentration, andmay hence represent proximal mobilization of titanium from the eclogite. Therefore, rutile veins canbe used as an exploration indicator for dissemination-type rutile deposits.

Precambrian Metamorphism of Tiya－Olokit Metamorphic Belt in Northern Balkal Region and its Metallogeny

The paper deals with results of petrological observations of the Precambrian rocks in the Tiya-Olokit metamorphic belt of the Northern Balkal region. Evoluhon of mstamorphic processes from Archean through to Paleozoic is characterized. Interrelations of metamorphic and ore formation processes are shown .Various genetic types of metamorphism and their metallogeulc speianzation (pyrihc-polylnetallic, gold-sulphide and others) are established.A great number of previously published analyses of garnets, biohtes, amphiholes, pyroxenes and muscovitde from metamorphic rocks have been made use of. The evoluhon of their compositions under progressive zoned metamorphism and diaphthoresis is revealed.

Diagenesis and Metamorphism of Triassic Flysch Along Profile Zoige-Lushan,Northwest Sichuan,China

We used illite and chlorite crystaHinities, index minerals, mineral assemblages, polytype and domain size of white mica, electron microprobe analysis （EMPA）, b0 geobarometer and chlorite geothermometer to quantify the diagenetic and metamorphic overprint on the Triassic flysch formations in the Songpan-Garze orogen along profile Zoige-Lushan, northwest Sichuan. Two anchizones, two epizones, one diagenetic zone and a transition belt in-between them are defined on the basis of the obtained data. lllite crystallinity correlates strongly with the best mean domain size of mica and moderately with chlorite crystallinity. 2M1 white mica polytype are observed within the epizone whilst 2M1 and 1M polytypes occur in the anchizone and diagenetic zone. Epizonal metamorphism reached maximum temperatures of 370℃±21℃ at low-to intermediate pressure conditions. Clay minerals underwent Ostwald ripening during metamorphism. Rocks from both sides of the Longmenshan fault reveal contrasting degrees of metamorphic overprint： on the northwest side of the Longmenshan fault, epimetamorphic conditions contrast with diagenetic rocks on the southeast side.

Mineralogical Evidence for Regional Metamorphism Overprinted by Contact Metamorphism

The Soursat metamorphic complex （SMC） in northwestern Iran is part of the Sanandaj- Sirjan metamorphic belt. The complex is composed of different metamorphic and plutonic rocks, but is dominated by metapelites composed of garnet, staurolite, kyanite, fibrolite, cordierite, and andalusite. Porphyroblasts in schists have the same fabric, and three stages of schistosity are present. The internal schistosity （Sn） inclusion trails are also offset by conjugate sets of extensional schistosity （Sn＋l） and a second （Sn＋2） that crenulates （Sn＋l）. Polyphase metamorphisms are present in the complex. Garnet, staurolite, kyanite, and fibrolite assemblage preserves conditions during the M1 metamorphic event. This assemblage yields a P-t estimate of 645±11℃ and 6.5±0.5 kbar. Other samples of the central part of SMC contain cordierite and andalusite （M2） overgrowth that yields a P- t estimate of 532±33℃ and 2.1±1.1 kbar.

Missed diagnosis of early gastric cancer or high-grade intraepithelial neoplasia

AIM: To investigate the causes of missed diagnosis of early gastric cancer (EGC) or high-grade intraepithelial neoplasia (HGIN) in Chongqing, China. METHODS: The present study summarizes 103 cases of EGC/HGIN detected by esophagogastroduodenos-copy (EGD) and pathological analysis from January 2010 to December 2011. Dimethyl silicone oil was administrated orally 15 min before the EGD procedures. The stomach was cleaned by repeated washing with saline when the gastroscope entered the stomach cavity. Suspected EGC lesions were subject to conventional biopsy sampling and pathological examinations. The correlation between lesion locations, endoscopic morphology of cancerous sites, training level of the examiners, pathological biopsies, and missed diagnosis was analyzed. RESULTS: Twenty-three cases were missed among the 103 cases (22.23%) of EGC/HGIN. The rate of missed EGC in the gastroesophageal junction (8/19, 42.1%) was significantly higher than at other sites (15/84, 17.86%) (χ2 = 5.253, P = 0.022). In contrast, the rate of missed EGC in the lower stomach body (2/14, 14.29%) was lower than at other sites (21/89,23.6%), but there were no significant differences (χ2 = 0.289, P = 0.591). The rate of missed EGC in the gastric antrum (5/33, 15.15%) was lower than at other sites (18/70, 25.71%), but there were no significant differences (χ2 = 1.443, P = 0.230). Endoscopists from less prestigious hospitals were more prone to not diagnosing EGC than those from more prestigious hospitals (χ2 = 4.261, P = 0.039). When the number of biopsies was < 4, the rate of missed diagnosis was higher (20/23, 89.96%) than for when there were > 4 biopsies (3/23, 13.04%) (P < 0.001). In addition, there was no significant difference in the rate of missed diagnosis in patients with 1-3 biopsy specimens (χ2 = 0.141, P = 0.932). CONCLUSION: Endoscopists should have a clear understanding of the anatomical characteristics of the esophagus/stomach, and endoscopic identification of early lesions increases with the number of biopsies.