Volume 120  ·   Issue 06  ·  2007

As we, the members of the present editorial board and all the editors of Chinese Medical Journal (CMJ),celebrate the 120th anniversary of the journal, the first and the most important thing that we should do is to pay our tribute to the founders of the journal and many others who worked for the journal as editors and members of the past editorial boards, the authors and readers of the journal and all the individuals and organizations that supported the journal for its existence and development during the past 120 years。

Abstract：Background Transforming growth factor beta (TGF-beta) plays an essential role in the regulation of normal physiologic processes of cells. TGF-beta has been shown to regulate several mitogen-a ctivated protein kinases (MAPK) pathways in several epithelial cells. However, the effects of TGF-beta on soft tissue sarcoma are seldom reported. Our previous studies suggested that there should be some other signal transduction pathways besides Smads, which are important to regulate the growth of human embryonal rhabdomyosarcoma (RMS) cells. In the present study, we examined the expression and functional relations of extracellular signal-regulated kinase 2 (ERK2) and Smad4 in human RMS tissue and a RMS cell line, RD.Methods RD cells and normal human primary skeletal myoblasts (Mb) were treated with TGF-beta1 to establish the expression profile of ERK2 at the mRNA and protein levels detected by RT-PCR and immunofluorescence.Immunohistochemistry was used to detect the expression of ERK2 and Smad4 in 50 tissue specimens of human RMS and 23 specimens of normal skeletal muscles. Follow-up of specimens was performed 6 months to 70 months later.Results RD cells and human RMS tissues showed the higher expression of ERK2 and Smad4 than the normal control,either the protein level or the mRNA level. And, exogenous TGF-beta1 stimulation can lead to higher expression of ERK2and its nuclear translocation, so TGF-beta1 can also activated MAPK (ERK2) pathway, resulting in a sustained activation of ERK2 for at least 2 hours. Immunohistochemistry analysis, however, showed that there was no correlation between ERK2 and Smad4 protein. The overexpression of ERK2 and Smad4 had no indicative effects on histological subtypes,histological grading, gender, age, and prognosis.Conclusions In RMS, signaling of TGF-beta1 from cell surface to nucleus can also be directed through the MAPK (ERK2) pathway besides the TGF-beta1/Smads pathway. The activation of ERK2 by TGF-beta1 may be Smad4independent. Moreover, there may be some other tanglesome relationships between the TGF-beta1/Smads pathway and the MAPK pathway which takes part in the development, invasion and metastasis of tumor cells。

Abstract：Background Large animal models with toxin-mediated pancreatic damage have been used extensively in researches with respect to diabetes mellitus and cardiovascular diabetic complications. The present study aimed to establish Chinese Guizhou minipig models with streptozotocin (STZ)-induced diabetes and characterize the animal models by analyzing inflammatory cytokine levels in aortic wall, such as tumor necrosis factor (TNF)-α, interleukin-1β (IL-1β) and interleukin-6 (IL-6).Methods Twenty-two male Chinese Guizhou minipigs (age, 4 to 6 months; weight, 20 kg to 30 kg) were divided into STZ-induced diabetic group (n=12) and control group (n=10). STZ (125 mg/kg) was administrated to induce hyperglycemia and afterwards insulin was used to control fasting blood glucose levels below 10 mmol/L. Oral glucose tolerance test (OGTT) was performed before and one month after STZ administration and serum concentrations of alanine transaminase, asparagine transaminase, albumin, blood urea nitrogen, creatinine, lipids and white blood cell count were measured before and six months later. Animals in both groups were euthanized after six months and pancreas was examined immunohistochemically for islet β cells. Aortic intima of diabetic minipigs and controls was analyzed for TNF-α level in tissue conditioned medium by Western blot. TNF-α, IL-1β and IL-6 mRNA levels in aortic intima were assayed by reverse transcription and polymerase chain reaction (RT-PCR).Results Significant elevation in serum glucose levels was observed one month and six months after STZ induction (P＜0.001) and markedly increased OGTT values were noted, compared with baseline data. The normal pancreas had many irregular sized islets and small clusters of islet β cells, while in pancreas of diabetic minipigs islet β cells almost disappeared. No statistical difference was notified in serum concentrations of biochemical examinations before and six months after STZ induction. Western blot demonstrated dramatically increased TNF-α level in aotic intima conditioned medium, and significant elevation of TNF-α, IL-1β and IL-6 mRNA levels was revealed by RT-PCR.Conclusions The present study has established Chinese Guizhou minipig models with STZ-induced diabetes.Inflammatory cytokines (TNF-α, IL-1β and IL-6) significantly elevated in aortic intima of diabetic minipigs。

Abstract：Background Advanced age independently predicts early and late mortality and major adverse cardiac events (MACE)after percutaneous coronary intervention (PCI). Randomized clinical trials indicate that sirolimus-eluting stent (SES)implantation reduces target lesion revascularization (TLR), but there are limited data on the impact of age on outcomes following SES implantation in patients with coronary artery disease (CAD) in real-world practice.Methods A total of 333 CAD patients with 453 lesions were enrolled in this study. Subjects were divided into two groups according to age. a young group (＜65 years old, 244 patients with 369 lesions) and elderly group (≥65 years old, 89patients with 113 lesions). Clinical follow-up and quantitative coronary angiography (QCA) were performed seven months after PCI.Results Baseline clinical, demographic, angiographic, and procedural chararcteristics were similar in both groups,except that there were more female patients in the elderly group (21.3% vs 9.8%, P=0.006). Primary success rate was similar in both groups (96.5% in young group vs 95.7% in elderly group, P＞0.05). During angiographic follow-up at 7months, binary in-stent restenosis and in-segment restenosis rates were not significantly different between the two groups (4.7% vs 1.8%; 9.7% vs 8.8%, P＞0.05 respectively). Both sub-acute and late thrombosis rates were similar in the two groups (0.3% vs 0.9% and 1.2% vs 0.9%, P＞0.05 respectively). TLR was not significantly different between the two groups (6.5% vs 3.5%; P=0.246). The rates of bleeding, stroke, angina rehospitalization during the follow-up period were also similar in both groups (P＞0.05 respectively).Conclusion Despite a high-risk clinical profile, coronary SES implantation can be safely and effectively performed in elderly patients with a similar procedural success rate, a low complication rate, and excellent 7-month outcomes。

Abstract：Background Restoration of blood flow to the ischemic liver lobes may paradoxically exacerbate tissue injury, which is called hepatic ischemia/reperfusion injury (IRI). Toll-like receptor 4 (TLR4), expressed on several liver cell types, and the nuclear factor-kappa B (NF-κB) signaling pathway are crucial to mediating hepatic inflammatory response. Because IRI is essentially a kind of profound acute inflammatory reaction evoked by many kinds of danger signals, we investigated TLR4/NF-κB signaling pathway activation in a murine model of partial hepatic IRI.Methods Wild-type mice (Wr, C3H/HeN) or TLR4 mutant mice (C3H/HeJ) were subjected to 45 minutes of partial hepatic ischemia followed by 1 hour, 3 hours of reperfusion. Sham group accepted the same procedure without the obstruction of blood supply. At the end of reperfusion, the compromise of liver function and the histological change of liver sections were measured as the severity of liver injury. The level of endotoxin in the portal vein was measured by limulus assay. NF-κB activation was determined by electrophoretic mobility shift assay (EMSA). The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in systemic blood after hepatic IRI were assessed by enzyme-linked immunosorbent assay (ELISA).Results The compromise of liver function and the morphological injuries in mutant mice were relieved more markedly than those in WT mice after partial hepatic IRI. NF-κB activation in WT mice was stronger than that in TLR4 mutant mice,and both were stronger than those in the sham operated mice (P＜0.01). Endotoxin in each group was undetectable. The levels of TNF-α and IL-1β in systemic blood were elevated in both strains, but lower in the sham operated group. These mediators were significantly decreased in TLR4 mutant mice compared with those in WT mice (P＜0.01).Conclusions The TLR4/NF-κB signaling pathway may mediate hepatic IRI triggered by endogenous danger signals.Inhibition of the TLR4/NF-κB pathway may be a potential therapeutic target for attenuating ischemia/reperfusion-induced tissue damage in some clinical settings。

Abstract：Background Human papillomaviruses (HPVs) can infect squamous or mucosal epithelia and cause cervical cancer or genital warts. Coinfection with multiple HPV types is a common finding of many epidemiological studies. Therefore, it is necessary to develop a vaccine, which can eradicate established HPV infections and prevent other HPV infections. In this study, we generated chimeric virus like particles (cVLPs) composed of HPV-6b L1, HPV-6b L2 and one artificial HPV-16 mE7 proteins.Methods The artificial HPV-16 mE7 gene was designed by codon modification, point mutation and gene shuffling then chemically synthesized and subcloned behind HPV-6b L2. HPV-6b L1 and L2-mE7 were expressed in insect cells by using Bac-to-Bac system. The generated cVLPs were purified by CsCl gradient ultracentrifuge and analyzed by immunoblot, electron microscope and haemagglutination assay.Results The HPV-6b L1 and L2-mE7 proteins were well expressed in insect cells and could selfassemble into cVLPs,whose diameter was about 55 nm and similar to that of HPV-6b L1/L2 VLPs. Intact cVLPs could be recognized by H6.M48 neutralizing monoclonal antibody and HPV-6b L2 polyclonal antibody, while the denatured cVLPs, but not the intact cVLPs, were reactive to HPV-16 E7 polyclonal antibody. HPV-6b L1/L2-mE7 cVLPs haemagglutinated mouse erythrocytes as efficiently as HPV-6b L1/L2 VLPs did.Conclusions The insertion of the 158 amino acid HPV-16 mE7 protein behind L2 did not disrupt the correct assembling of cVLPs. The morphological characteristics and haemagglutinating activity of cVLPs were similar to those of HPV-6b L1/L2 VLPs. The cVLPs retained conformational B cell epitopes of HPV-6 VLPs and HPV-16 mE7 protein had an internal location in the cVLPs. Therefore, large modified E7 protein with higher immunogenicity could be incorporated into cVLPs by fusing to the C-terminus of L2, which would help to improve the therapeutic effects of L1/L2-E7 cVLPs。

Abstract：Background Although DNA vaccine is considered as the next generation of vaccine, most DNA vaccine candidates are still suffering from the relatively weak immunogenicity despite the increased dosage of plasmid DNA administered. In order to enhance the immune responses elicited by a codon-optimized HIV gag DNA vaccine, a modified plasmid vector pDRVI1.0 and a booster immunization with replicating Tiantan vaccinia (RTV) strain expressing the same gene were employed.Methods Vector pDRVI1.0 was constructed through inserting the 72-bp element from the SV40 enhancer, which was reported promoting nuclear transport of plasmid DNA, to the upstream of cytomegalovirus enhancer/promoter region of the plasmid vector pVR1012. Gene expression levels from expression plasmids based on pDRVI1.0 and pVR1012 were tested. Humoral and cellular immune responses induced by DNA vaccine alone or DNA prime-RTV boost regimen were determined in mice.Results It was shown that the 72-bp element significantly enhanced the gene expression level in non-dividing cells.gag-specific humoral and cellular immune responses induced by DNA vaccination were both significantly improved, while the Th1/Th2 balance was not obviously affected by the 72-bp element. RTV boosting further significantly enhanced DNA vaccine-primed antibody and T cell responses in a Th1-biased manner.Conclusions The 72-bp SV40 enhancer element should be included in the DNA vaccine vector and RTV strain is a very efficient live vector for boosting immunization。

Abstract：Background Fibroblast growth factor 9 (FGF9), expressed in brain, kidney and developing skeletal tissues, can physiologically inhibit endochondral ossification; but little is known about how FGF9 affects osteoblasts and its detailed regulatory mechanism. Here we examined the effect of FGF9 on the activity of the murine Runt-related transcription factor2 (Runx2) gene promoter in preosteoblast MC3T3-E1 and premyoblast C2C12 cells.Methods Plasmids containing the Runx2 promoter region were transfected into MC3T3-E1 and C2C12 cells and stably transfected cell lines were established. The method of luciferase reporter gene activation was used to examine the effects of FGF9 on the promoter activity.Results FGF9 (10 ng/ml) increased Runx2 promoter activity in MC3T3-E1 cells. When MC3T3-E1 cells were treated with FGF9 plus the various inhibitors or activator of the intracellular signaling transducation pathways, including 10μmol/L U0126 (the inhibitor of mitogen-activated protein kinase kinase), 10 μmol/L SB203580 (the inhibitor of p38/mitogen activated protein kinase), or 1 μmol/L C6 ceramide (an activator of mitogen activated protein kinase), the luciferase expression did not change significantly compared with that of the cells treated with FGF9 only. However, when C2C12 cells were treated with 10 ng/ml FGF9, Runx2 gene promoter activity first decreased and then increased over a period of 1 to 5 days. Among the above inhibitors, only U0126 (10 μmol/L) completely blocked the effects of FGF9 on Runx2 gene promoter activity.Conclusions Our data showed that FGF9 can affect Runx2 gene promoter activity in MC3T3-E1 and C2C12 cells. The action of FGF9 appears to depend partly on the mitogen-activated protein kinase kinase/mitogen-activated protein kinase pathways in C2C12 cells。

Abstract：Background After myocardial infarction, specific growth factors promote cardiac angiogenisis, leading to a therapeutic effect. Although this effect is mediated by specific receptors in the endothelium of the cardiac microvasculature, few studies have investigated dynamic changes in their expression. We explored this phenomenon in a murine model.Methods We observed the mRNA expression of receptors by specific angiogenesis gene microarray at day 3 and day 7after infarction. The vascular endothelial growth factor (VEGF) receptor Fik-1 was observed at the protein level at day 3and day 7 by immunohistochemistry. The dynamic expression of fibroblast growth factor receptor-1 (FGFR-1) mRNA in the border zone and the noninfarcted zone at day 3, day 7, day 14, and day 42 was investigated by real-time PCR.Statistical significance was analyzed with SPSS 10.0 software using one-way analysis of variance (ANOVA).Results Three days after infarction, 9 receptors in the border zone and 7 receptors in the noninfarcted zone were down-regulated. Two receptors in the infarct edge and 5 receptors in the distant myocardium were up-regulated. However,at day 7, 11 receptors in the border zone were up-regulated, and only one was down-regulated. In the border zone, Fik-1levels decreased at day 3 but increased significantly at day 7. Real-time PCR showed that FGFR-1 mRNA decreased markedly in the border zone at day 3 but increased afterward for at least 6 weeks. In the early stage (3 days) after infarction, the expression of receptors had decreased to some extent. However, at day 7, receptor expression was active and had moved from the distant noninfarcted zone to the border zone as a part of the acute repair process.Conclusion Selecting the proper growth factors to target receptors with protective activity, and determining appropriate therapeutic timing may be important to the success of therapeutic angiogenesis。

Abstract：Background With the significant improvement in the survival of patients with nasopharyngeal carcinoma (NPC)undergoing radiotherapy and the growing availability of the sophisticated imaging modalities, the number of radiation encephalopathy (RE) cases relating to NPC radiotherapy is increasing. In this study, we investigated the metabolic and density changes of the compromised brain tissues during delayed RE using a positron-emission tomography-computed tomography (PET/CT) to provide clinical evidences for the diagnosis of delayed RE following radiotherapy for NPC.Methods The PET/CT manifestations and the clinical data of 53 pathologically confirmed NPC patients with delayed RE following radical radiotherapy and 15 healthy volunteers were investigated. The standardized uptake values (SUV) of the bilateral temporal lobes, the occipital lobe and the brain stem were measured respectively; and then the metabolic reduction rate of 88 temporal lobes and 13 brain stems were calculated for a statistical comparison between the two groups.Results The earliest case of delayed RE in the investigated patients occurred 1.5 years after radiotherapy. Delayed RE frequently involved the inferior temporal lobe. For patients with delayed RE confirmed by clinical symptoms and imaging findings, PET maintained a 100% coincidence rate with CT; however, in the 25 temporal lobes of the 35 delayed RE patients, PET revealed obvious hypometabolic changes whereas CT displayed normal density. The incidence of brain stem metabolic reductions was 24.5% (13/53) in the investigated patients, including 4 patients with hypometabolic changes shown by PET and negative finding shown by CT. The incidence of granuloma adjacent to the hypometabolic region in the temporal lobe was 12.5% (11/88).Conclusion Delayed RE patients exhibit significant hypometabolic changes in the inferior temporal lobe, captured by PET much earlier than by CT. PET/CT offers a valuable means for the diagnosis of delayed RE in subacute stages and granuloma formation。

Abstract：Background Dysregulation of apoptosis has been implicated not only in carcinogenesis and tumor progression but also in tumor recurrence. We investigated whether the expression of X-linked inhibitor of apoptosis (XIAP) might predict early recurrence in patients with non-muscular invasive bladder cancer.Methods The cohort comprised 176 consecutive patients with primary superficial bladder cancer treated with transurethral resection. Immunohistochemical staining using the standard avidin-biotin-peroxidase technique and RT-PCR were used to detect XIAP protein and mRNA expressions in cancer tissues. The relationship between XIAP expression and clinicopathological characteristics, cancer recurrence were analyzed.Results XIAP expression was observed in 108 cases (61.4%) and no expression in 68. There was no correlation between XIAP expression rate and the tumor pathological grade, but was an apparent trend toward the increased XIAP levels from well (G1) to poor (G3) differentiated cancer. Eighty-two (46.6%) patients experienced tumor recurrence at a mean of 28.6 months of the follow-up; 66 of them expressed XIAP (61.1%) and 16 were XIAP negative (23.5%). Twelve patients presented with invasive disease at the time of relapse and all of them expressed XIAP. Patients without XIAP expression or with low tumor grades had significantly higher recurrence-free survival than those with XIAP expression(log rank test P=0.0015) or high tumor grades (log rank test P＜0.001). Multivariate analysis revealed that XIAP expression, tumor grade, and tumor number were independent predictors for the recurrence of non-muscular invasive bladder cancer (P=-0.004, 0.016, and 0.043, respectively).Conclusions XIAP may be considered as a new independent prognostic marker for early recurrence of non-muscular invasive bladder cancer。

Abstract：Background Allogeneic stem cell transplantation is a potential curative approach in patients with multiple myeloma.The very high transplant related mortality associated with standard allogeneic stem cell transplantation is currently the major limitation to wider use of this potentially curative treatment modality. The challenge for clinical investigators is to reduce the incidence of post-transplant complications for patients receiving autologous hematopoietic stem cell transplantion for multiple myeloma. In this study the toxicity and efficacy of modified myeloablative conditioning regimen followed by allogeneic stem cell transplantation was investigated in patients with multiple myeloma.Methods The conditioning regimen consisted of hydroxyurea, cytarabine, busulfan, cyclophosphamide, and semustine.Ten patients underwent allogeneic transplantation among them hydroxyurea (40 mg/kg) was administered twice on day -10 and cytarabine (2 g/m2) was given on day -9, busulfan was administered orally in four divided doses daily for 3 days (days -8 to -6). The dose of busulfan was 12 mg/kg in the protocol followed by cyclophosphamide intravenously over 1hour on days -5 and -4 (1.8 g/m2), and with semustine (Me-CCNU) 250 mg/m2 on day -3.Results Chimerism data were available on all patients and all patients achieved full donor chimerism without graft failure. Six patients had not acute graft-versus-host disease (GVHD, 36.4%; 95% CI:13.9%-38.6%). Two patients (18.2%) developed grade Ⅰ acute GVHD (95% CI:10.9%-35.9%) and grade Ⅱ acute GVHD occurred in one patient (9.1%;95% CI: 8.4%-32.3%). Severe grade Iva GVHD was seen in one patient, who died from acute GVHD. The incidence of chronic GVHD was 22.2% (95% CI: 11.7%-36.7%), among them one died of severe grade IV GVHD and one developed multiorgan failure on day +170; the treatment-related mortality was 22.0% (95% CI: 10.3%-34.1%). The overall 4-year survival rate was 67.8% (95% CI: 16.3%-46.7%). The estimated 4-year progression-free survival rate was 58.5% (95%CI: 13.7%-41.8%). The 4-year complete remission was 72.7% (95% CI: 27.8%-49.6%). One patient relapsed after 4months and achived the complete remission after receiving the donor lymphocyte infusion.Conclusions Modified conditioning regimen busulfan-cyclophosphamide with peripheral blood stem cells+bone marrow cells transplantation result in a low incidence of severe GVHD with a relatively low treatment-related mortality,high complete remission rates and a long-term survival。

Abstract：Background Conventional treatment for non-small cell lung cancer (NSCLC) brain metastases (BM) is whole-brain radiotherapy (WBRT). The efficacy is limited. It might be increased by a Potent radiosensitizer such as gemcitabine,which is believed to cross the disrupted blood-brain barrier. The primary objective of this study was to determine the maximum tolerated dose (MTD) of weekly gemcitabine given concurrently with WBRT.Methods Patients with BM from NSCLC were included. The dose of WBRT was 3750 cGy (total 15 times, 3 weeks).Gemcitabine was given concurrently with WBRT on days 1, 8 and 15. The starting dose was 400 mg/m2, escalated by100 mg/m2 increments. At least three patients were included per level. Dose limiting toxicity (DLT) was defined as grade 4hematological or grade 2 neurological toxicity. When two or more patients experience DLT, the MTD was reached.Results A total of 16 patients were included; 69% had a performance status (PS) 1 (Eastern Cooperative Oncology Group, ECOG). A total of 69% had concurrent active extra cranial diseases. All had more than 3 BM. Up to 600 mg/m2(Ievel 3) no neurology toxicity was observed. At 600 mg/m2 two out of 9 patients developed grade 4 thrombocytopenia.One of the two patients' thrombocytopenia was confused with disseminated intravascular coagulation (DIC). At 700mg/m2 two out of 4 patients developed neurotoxicities. One developed grade 3 seizure and cognitive disorder. Another patient developed suspected grade 2 muscle weakness.Conclusions The MTD was reached at a dose of 700 mg/m2. The dose of 600 mg/m2 would be considered for further study。

Abstract：Background Surgical treatment options for patients with cirrhosis and portal hypertension are complicated. In this study,we evaluated the effectiveness of a new treatment strategy, splenic auto-transplantation and oesophageal transection anastomosis. We report results from clinical observations, splenic immune function and portal dynamics in 274 patients.Methods From 1979 to 2005, 274 cirrhosis patients with portal hypertension underwent the new treatment strategy, and were followed up to compare results with those patients who underwent traditional surgical treatment. From 1999 to 2002,a randomized controlled trial (RCT) was performed on 40 patients to compare their post-operative immune function. From 1994 to 2006, another RCT enrolled 28 patients to compare portal dynamics using three-dimensional dynamic contrast-enhanced magnetic resonance angiography (3D DEC MRA) investigation post operation.Results Among 274 patients (mean age 41.8 years), the emergency operative mortality (4.4%), selective operative mortality (2.2%), complication rate (17.9%), prevalence of hepatic encephalopathy (＜1%), rate of portal hypertension gastritis (PHG) bleeding (9.1%), and morbidity of hepatic carcinoma (8%) were similar to those patients undergoing traditional operation; the spleen immunology function (Tuftsin, IgM) decreased in both groups 2 months post operation,but this decrease did not reach statistical significance. Through 3D DCE MRA, the cross sectional area and the velocity and volume of blood flow of the main portal vein decreased significantly after operation in both groups. The velocity and volume of blood flow in the auto-transplantation group was significantly lower than that in the control group.Conclusions Splenic auto-transplantation and esophageal transection anastomosis is a safe, effective, and reasonable treatment strategy for patients with portal hypertension with varicial bleeding. It not only can correct hypersplenism, but may also achieve complete hemostasis. Spleens auto-transplanted into the retroperitoneal space can preserve immune function and establish broad collateral circulation。

The chemokine receptors CCR5 and CXCR4 play an important role as coreceptors for human immunodeficiency virus type 1 (HIV-1) entring into cells.HIV-1 isolates can be distinguished by the chemokine coreceptors. Nonsyncytium inducing (NSI), macrophage tropic viruses utilizing CCR5, are called R5 viruses;syncytium inducing (SI) isolates use CXCR4 and known as X4 viruses.

Perivascular epithelioid cell rumor (PEComa) is a rare mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. The family of PEComa includes angio-myolipoma (AML), clear cell "sugar" tumors of the lung (CCST), lymphangioleiomyomatosis (LAM), clear cell myomelanocytic tumor of the falciform/ligamentum teres (CCMT), and clear cell tumors of the pancreas,rectum, peritoneum, uterine, vagina, thigh, and heart.They are very rare besides AML, CCST, and LAM.1 To our knowledge, only 84 cases of PEComa have been reported, 30 of them occurred in the uterus.2,3 Here we report 3 cases of uterine PEComa and discuss its pathological features and differential diagnosis。