Absence of enhancement in a lesion does not preclude primary central nervous system T-cell lymphoma:A case report

BACKGROUND Primary central nervous system lymphoma(PCNSL)is a non-Hodgkin lymphoma that originates in the central nervous system(CNS)and is exclusively limited to the CNS.Although most PCNSLs are diffuse large B-cell lymphomas,primary CNS T-cell lymphomas(PCNSTLs)are rare.PCNSTLs typically demonstrate some degree of enhancement on contrast-enhanced magnetic resonance imaging(MRI).To the best of our knowledge,non-enhancing PCNSTL has not been reported previously.CASE SUMMARY A 69-year-old male presented to the neurology department with complaints of mild cognitive impairment and gradual onset of left lower leg weakness over a span of two weeks.Initial MRI showed asymmetric T2-hyperintense lesions within the brain.No enhancement was observed on the contrast-enhanced T1 image.The initial diagnosis was neuro-Behçet’s disease.Despite high-dose steroid therapy,no alterations in the lesions were identified on initial MRI.The patient’s symptoms deteriorated further.An MRI performed one month after the initial scan revealed an increased lesion extent.Subsequently,brain biopsy confirmed the diagnosis of PCNSTL.The patient underwent definitive combined chemoradiotherapy.However,the patient developed bacteremia and died of septic shock approximately three months after diagnosis.CONCLUSION The absence of enhancement in the lesion did not rule out PCNSTL.A biopsy approach is advisable for pathological confirmation.

Rare primary gastric peripheral T-cell lymphoma not otherwise specified:A case report

BACKGROUND Gastrointestinal lymphoma typically arises in the stomach,small bowel,or colorectum and is usually a B-cell lymphoma.However,primary T-cell lymp-homas originating in the stomach are particularly rare.Gastric peripheral T-cell lymphoma-not otherwise specified(PTCL-NOS)is an extremely rare subtype.CASE SUMMARY We report a 63-year-old male presenting with epigastric pain.Esophagogastro-duodenoscopy revealed a large ulcerative lesion in the gastric cardia.Biopsy and immunohistochemical profiling confirmed PTCL-NOS.Imaging indicated stage II disease involving the stomach and intra-abdominal lymph nodes.The patient is planned to undergo cyclophosphamide,doxorubicin,vincristine,and prednisone or cyclophosphamide,doxorubicin,vincristine,prednisone,and etoposide chemo-therapy.CONCLUSION This case highlights the necessity of considering PTCL-NOS in differential diag-noses of gastric lesions.Comprehensive histopathological and immunohistoche-mical analysis is crucial for accurate diagnosis and guiding treatment.

Plasmacytosis mimicking multiple myeloma in angioimmunoblastic T-cell lymphoma:A case report and review of literature

BACKGROUND Angioimmunoblastic T-cell lymphoma(AITL)is a common subtype of peripheral T-cell lymphoma.Approximately half of patients with AITL may concurrently present with hypergammaglobulinemia.Increased numbers of plasma cells in the bone marrow are commonly observed at diagnosis.These tumors mimic plasma cell myelomas,hindering a conundrum of clinical diagnoses and potentially delaying appropriate treatment.CASE SUMMARY A 78-year-old woman experienced poor appetite,weight loss of 5 kg,fatigue 2 months before presentation,and shortness of breath 2 d before presentation,but no fever or night sweats.Physical examination revealed splenomegaly and many palpable masses over the bilateral axillary regions,approximately>2 cm in size,with rubbery consistency and no tenderness.Blood tests revealed anemia and thrombocytopenia,lactate dehydrogenase level of 153 U/L,total protein level of 10.9 g/dL,albumin to globulin ratio of 0.2,and immunoglobulin G level more than the upper limit of 3000 mg/dL.The free kappa and lambda light chain concentrations were 451 and 614 mg/L,respectively.A pathological examination confirmed the diagnosis of AITL.The initial treatment was the cyclophosphamide,epirubicin,vincristine,and prednisolone regimen.Following this treatment,pleural effusion was controlled,and the patient was discharged in a stable condition and followed up in our outpatient department.CONCLUSION This report highlights the importance of differentiating reactive plasmacytosis from plasma cell myeloma in patients with hypergammaglobulinemia.A precise diagnosis of AITL requires a comprehensive evaluation,involving clinical,immunophenotypic,and histological findings conducted by a multidisciplinary team to ensure appropriate treatment.

Mutations in Ras homolog family member A in patients with peripheral T-cell lymphoma and implications for personalized medicine

Genome sequencing has revealed frequent mutations in Ras homolog family member A(RHOA)among various cancers with unique aberrant profiles and pathogenic effects,especially in peripheral T-cell lymphoma(PTCL).The discrete positional distribution and types of RHOA amino acid substitutions vary according to the tumor type,thereby leading to different functional and biological properties,which provide new insight into the molecular pathogenesis and potential targeted therapies for various tumors.However,the similarities and discrepancies in characteristics of RHOA mutations among various histologic subtypes of PTCL have not been fully elucidated.Herein we highlight the inconsistencies and complexities of the type and location of RHOA mutations and demonstrate the contribution of RHOA variants to the pathogenesis of PTCL by combining epigenetic abnormalities and activating multiple downstream pathways.The promising potential of targeting RHOA as a therapeutic modality is also outlined.This review provides new insight in the field of personalized medicine to improve the clinical outcomes for patients.

Monomorphic epitheliotropic intestinal T-cell lymphoma with bone marrow involved: A case report

BACKGROUND Monomorphic epithelial intestinal T-cell lymphoma(MEITL)is a rare type of peripheral T-cell lymphoma.The clinical manifestations are diarrhea,abdominal pain,perforation and an abdominal mass.CASE SUMMARY We present a 52-year-old female patient who was diagnosed with MEITL.Further disease progression was observed after multiline chemotherapy.Eventually,the patient died of a severe infection.CONCLUSION MEITL is a rare intestinal primary T-cell lymphoma with aggressive behavior,a high risk of severe life-threatening complications,and a poor prognosis.

Primary pancreatic peripheral T-cell lymphoma:A case report

BACKGROUND Primary pancreatic lymphoma(PPL)is an exceedingly rare tumor with limited mention in scientific literature.The clinical manifestations of PPL are often nonspecific,making it challenging to distinguish this disease from other panc-reatic-related diseases.Chemotherapy remains the primary treatment for these individuals.CASE SUMMARY In this case study,we present the clinical details of a 62-year-old woman who initially presented with vomiting,abdominal pain,and dorsal pain.On further evaluation through positron emission tomography-computed tomography,the patient was considered to have a pancreatic head mass.However,subsequent endoscopic ultrasonography-guided fine needle aspiration(EUS-FNA)revealed that the patient had pancreatic peripheral T-cell lymphoma,not otherwise specified(PTCL-NOS).There was a substantial decrease in the size of the pancreatic mass after the patient underwent a cycle of chemotherapy comprised of brentuximab vedotin,decitabine,and oxaliplatin(brentuximab vedotin and Gemox).The patient had significant improvement in radiological findings at the end of the first cycle.CONCLUSION Primary pancreatic PTCL-NOS is a malignant and heterogeneous lymphoma,in which the clinical manifestations are often nonspecific.It is difficult to diagnose,and the prognosis is poor.Imaging can only be used for auxiliary diagnosis of other diseases.With the help of immunostaining,EUS-FNA could be used to aid in the diagnosis of PPL.After a clear diagnosis,chemotherapy is still the first-line treatment for such patients,and surgical resection is not recommended.A large number of recent studies have shown that the CD30 antibody drug has potential as a therapy for several types of lymphoma.However,identifying new CD30-targeted therapies for different types of lymphoma is urgently needed.In the future,further research on antitumor therapy should be carried out to improve the survival prognosis of such patients.

Characteristics and distinct prognostic determinants of individuals with hepatosplenic T-cell lymphoma over the past two decades

BACKGROUND Hepatosplenic T-cell lymphoma(HSTCL)is a rare and aggressive peripheral T-cell lymphoma with historically dismal outcomes,representing less than one percent of non-Hodgkin lymphomas.Given its rarity,the true incidence of HSTCL is unknown and most data have been extrapolated through case reports.To the best of our knowledge,the largest and most up to date study addressing the epidemiology and outcomes of patients with HSTCL in the United States covered a period from 1996 to 2014,with a sample size of 122 patients.AIM To paint the most updated epidemiological picture of HSTCL.METHODS A total of 186 patients diagnosed with HSTCL,between 2000 and 2017,were ultimately enrolled in our study by retrieving data from the Surveillance,Epidemiology,and End Results database.We analyzed demographics,clinical characteristics,and overall mortality(OM)as well as cancer-specific mortality(CSM)of HSTCL.Variables with a P value<0.01 in the univariate Cox regression were incorporated into the multivariate Cox model to determine the independent prognostic factors,with a hazard ratio of greater than 1 representing adverse prog-nostic factors.CONCLUSION Overall,the outlook for this rare malignancy is very grim.In this retrospective cohort study of the United States population,non-Hispanic blacks and the elderly had a higher CSM.This data highlights the need for larger prospective studies to investigate factors associated with worse prognosis in one ethnic group,such as treatment delays,which have been shown to increase mortality in this racial/ethnic group for other cancers.

2022 Chinese expert consensus and guidelines on clinical management of toxicity in anti-CD19 chimeric antigen receptor T-cell therapy for B-cell non-Hodgkin lymphoma

Adoptive cellular immunotherapy with chimeric antigen receptor(CAR)T cells has emerged as a novel modality for treating relapsed and/or refractory B-cell non-Hodgkin lymphoma(B-NHL).With increasing approval of CAR T-cell products and advances in CAR T cell therapy,CAR T cells are expected to be used in a growing number of cases.However,CAR T-cell-associated toxicities can be severe or even fatal,thus compromising the survival benefit from this therapy.Standardizing and studying the clinical management of these toxicities are imperative.In contrast to other hematological malignancies,such as acute lymphoblastic leukemia and multiple myeloma,anti-CD19 CAR T-cell-associated toxicities in B-NHL have several distinctive features,most notably local cytokine-release syndrome(CRS).However,previously published guidelines have provided few specific recommendations for the grading and management of toxicities associated with CAR T-cell treatment for B-NHL.Consequently,we developed this consensus for the prevention,recognition,and management of these toxicities,on the basis of published literature regarding the management of anti-CD19 CAR T-cell-associated toxicities and the clinical experience of multiple Chinese institutions.This consensus refines a grading system and classification of CRS in B-NHL and corresponding measures for CRS management,and delineates comprehensive principles and exploratory recommendations for managing anti-CD19 CAR T-cell-associated toxicities in addition to CRS.

Intestinal T-cell lymphomas:A retrospective analysis of 68 cases in China

AIM: To investigate the clinical features, diagnosis, treatment and prognosis of intestinal T-cell lymphomas (ITCL) by retrospective analysis.

Monomorphic epitheliotropic intestinal T-cell lymphoma presenting as melena with long-term survival: A case report and review of literature

BACKGROUND Monomorphic epitheliotropic intestinal T-cell lymphoma(MEITL)is a rare primary intestinal T-cell lymphoma,previously known as enteropathy-associated T-cell lymphoma type II.MEITL is an aggressive T-cell lymphoma with a poor prognosis and high mortality rate.The known major complications of MEITL are intestinal perforation and obstruction.Here,we present a case of MEITL that was diagnosed following upper gastrointestinal bleeding from an ulcerative duodenal lesion,with recurrence-free survival for 5 years.CASE SUMMARY A 68-year-old female was admitted to our hospital with melena and mild anemia.An urgent esophagogastroduodenoscopy(EGD)revealed bleeding from an ulcerative lesion in the transverse part of the duodenum,for which hemostatic treatment was performed.MEITL was diagnosed following repeated biopsies of the lesion,and cyclophosphamide,doxorubicin,vincristine,and prednisone(CHOP)chemotherapy was administered.She achieved complete remission after eight full cycles of CHOP therapy.At the last follow-up examination,EGD revealed a scarred ulcer and 18Fluorodeoxyglucose(18FDG)positron emission tomography/computed tomography showed no abnormal FDG accumulation.The patient has been in complete remission for 68 mo after initial diagnosis.CONCLUSION To rule out MEITL,it is important to carefully perform histological examination when bleeding from a duodenal ulcer is observed.

Transcriptome sequencing analysis of ursolic acid-mediated proliferation suppression on cutaneous T-cell lymphoma cells

Background:Ursolic acid is a triterpenoid compound found in natural plants that exhibits antiproliferative effects in various cancer cells.Our study is the first to demonstrate the strong inhibitory effects of ursolic acid on the proliferation of cutaneous T-cell lymphoma(CTCL)cells.We aimed to further investigate the underlying mechanism of the proliferation inhibition induced by ursolic acid in CTCL cells using transcriptome sequencing.Methods:Cell counting kit-8 assays were used to observe the effects of six traditional medicine monomers on the proliferation of CTCL cells.Transcriptome sequencing was used to identify differentially expressed genes after ursolic acid treatment.Bioinformatics analysis was performed to determine the potential mechanism.Real-time quantitative PCR and western blotting analyses were performed to confirm the sequencing results and verify the possible mechanisms of ursolic acid-mediated proliferation inhibition in CTCL cells.Results:Ursolic acid exhibited the strongest inhibitory effect on the proliferation of CTCL cells among the six traditional medicine monomers.Transcriptome sequencing analysis showed that 2,466 genes were significantly altered.Combined with Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis and protein-protein interaction network analysis,the interaction of various pathways and signaling molecules,such as tumor necrosis factor-α,NLR family pyrin domain containing 1,c-Jun N-terminal kinase,and melanoma differentiation-associated gene 5,accounted for the anti-tumor effects of ursolic acid in CTCL cells.Conclusion:Ursolic acid significantly inhibited the proliferation of CTCL cells,and our study laid a theoretical foundation for the future treatment of CTCL using ursolic acid.

Angioimmunoblastic T-cell lymphoma induced hemophagocytic lymphohistiocytosis and disseminated intravascular coagulopathy: A case report

BACKGROUND Angioimmunoblastic T-cell lymphoma(AITL) is a subtype of peripheral T-cell lymphoma, with heterogenous clinical manifestations and poor prognosis. Here,we report a case of AITL induced hemophagocytic lymphohistiocytosis(HLH)and disseminated intravascular coagulopathy(DIC).CASE SUMMARY An 83-year-old man presented with fever and purpura of both lower limbs for one month. Groin lymph node puncture and flow cytometry indicated a diagnosis of AITL. Bone marrow examination and other laboratory related indexes indicated DIC and HLH. The patient rapidly succumbed to gastrointestinal bleeding and septic shock.CONCLUSION This is the first reported case of AITL induced HLH and DIC. AITL is more aggressive in older adults. In addition to male gender, mediastinal lymphadenopathy, anaemia, and sustained high level of neutrophil-to-lymphocyte ratio may indicate a greater risk of death. Early diagnosis, early detection of severe complications, and prompt and effective treatment are vital.

Hemophagocytic lymphohistiocytosis after autologous stem cell transplantation in angioimmunoblastic T-cell lymphoma:A case report

BACKGROUND Angioimmunoblastic T-cell lymphoma(AITL), a unique subtype of peripheral Tcell lymphoma, has relatively poor outcomes. High-dose chemotherapy with autologous stem cell transplantation(ASCT) can achieve complete remission and improve outcomes. Unfortunately, subsequent T-cell lymphoma-triggered hemophagocytic lymphohistiocytosis(HLH) has a worse prognosis than B-cell lymphoma-triggered HLH.CASE SUMMARY We here report a 50-year-old woman with AITL who achieved a favorable outcome after developing HLH 2 mo after receiving high-dose chemotherapy/ASCT. The patient was initially admitted to our hospital because of multiple enlarged lymph nodes. The final pathologic diagnosis, made on biopsy of a left axillary lymph node was AITL(Stage Ⅳ, Group A). Four cycles of the following chemotherapy regimen were administered: Cyclophosphamide 1.3 g, doxorubicin 86 mg, and vincristine 2 mg on day 1;prednisone 100 mg on days 1-5;and lenalidomide 25 mg on days 1-14. The interval between each cycle was 21 d. The patient received a conditioning regimen(busulfan, cyclophosphamide, and etoposide) followed by peripheral blood stem cell infusion. Unfortunately, she developed sustained fever and a low platelet count 17 d after ACST, leading to a diagnosis of HLH after ASCT. During treatment, she experienced thrombocytopenia and Pneumocystis carinii pneumonia. The patient was successfully treated with etoposide and glucocorticoids.CONCLUSION It is possible that development of HLH is related to immune reconstitution after ASCT.

Nodal peripheral T-cell lymphomas in the new classification systems

Peripheral T-cell lymphomas(PTCLs)encompass a biologically diverse group of non-Hodgkin lymphomas derived from mature T-lymphocytes.Most PTCLs present as nodal diseases and include several subtypes characterized by distinct clinical and pathologic features,and will be the focus of this editorial.The PTCL group presenting as rare distinctive extranodal diseases will not be discussed.While T-cell neoplasms,like B-cell lymphomas,recapitulate stages of normal differentiation,the biology is notably intricate and exhibits remarkable plasticity.

Effect of chidamide on treating hepatosplenic T-cell lymphoma: A case report

BACKGROUND Hepatosplenic T-cell lymphoma(HSTCL)is a rare subtype of non-Hodgkin’s lymphoma,which has an aggressive clinical course and an extremely poor prognosis.Chidamide is a novel,orally active,benzamide-type histone deacetylase(HDAC)inhibitor that has been used for peripheral T-cell lymphoma(PTCL)treatment.However,to date,there has been no report of the treatment and effect of the HDAC inhibitor chidamide in HSTCL,which is a special subtype of PTCL.CASE SUMMARY A 45-year-old male patient was admitted with splenomegaly and slight bicytopenia.He was diagnosed with HSTCL via splenectomy.The patient was treated with fractionated cyclophosphamide,vincristine,doxorubicin,and dexamethasone alternating with high-dose methotrexate and cytarabine regiment as inductive therapy.Unfortunately,the disease progressed rapidly during chemotherapy before a suitable allogeneic gene transplant donor was found.The chidamide-combined chemotherapy regimen and single-drug oral maintenance regimen achieved complete remission,duration of response of 9 mo,and overall survival of 15 mo.CONCLUSION The novel agent chidamide can be used in HSTCL to achieve deep remission and improve the duration of response and overall survival.

Adult T-cell leukemia/lymphoma presenting multiple lymphomatous polyposis

Multiple lymphomatous polyposis (MLP) is an unusual form of non-Hodgkin's lymphoma characterized by polyps throughout the gastrointestinal tract. It has been reported that most MLP are observed in cases with mantle cell lymphoma of B-cell type. We herein present a case of a 66-year-old man with adult T-cell leukemia/lymphoma (ATLL). Colonoscopy revealed MLP throughout the colon and histopathological findings of ATLL cell infiltration. The patient died despite combination of chemotherapy. The literature of manifestations of colonic involvement of ATLL isreviewed and the importance of endoscopic evaluation to differentiate ATLL intestinal lesions from opportunistic infectious enterocolitis is discussed.

Genetic abnormalities assist in pathological diagnosis and EBVpositive cell density impact survival in Chinese angioimmunoblastic T-cell lymphoma patients

Objective:To explore the application of genetic abnormalities in the diagnosis of angioimmunoblastic T-cell lymphoma(AITL)and the reliable pathological prognostic factors.Methods:This study included 53 AITL cases,which were reviewed for morphological patterns,immunophenotypes,presence of Hodgkin and Reed-Sternberg(HRS)-like cells,and co-occurrence of B cell proliferation.The Epstein-Barr virus(EBV)-positive cells in tissues were counted,and cases were classified into“EBV encoded RNA(EBER)high-density”group if>50/HPF.Targeted exome sequencing was performed.Results:Mutation data can assist AITL diagnosis:1)with considerable HRS-like cells(20 cases):RHOA mutated in 14 cases(IDH2 co-mutated in 3 cases,4 cases with rare RHOA mutation),TET2 was mutated in 5 cases(1 case comutated with DNMT3A),and DNMT3A mutated in 1 case;2)accompanied with B cell lymphoma(7 cases):RHOA mutated in 4 cases(1 case had IDH2 mutation),TET2 mutated in 2 cases and DNMT3A mutated in 1 case;3)mimic peripheral T cell lymphoma,not otherwise specified(5 cases):RHOA mutated in 2 cases(IDH2 co-mutated in 1 case),TET2 mutated in 3 cases,and DNMT3A mutated in 1 case;4)pattern 1(1 case),RHOA and TET2 co-mutated.Besides RHOAG17V(30/35),rare variant included RHOAK18N,RHOAR68H,RHOAC83Y,RHOAD120G and RHOAG17del,IDH2R172 co-mutated with IDH2M397V in one case.There were recurrent mutations of FAT3,PCLO and PIEZO1 and genes of epigenetic remodeling,T-cell activation,APC and PI3K/AKT pathway.EBER high-density independently indicated adverse overall survival and progression-free survival(P=0.046 and P=0.008,KaplanMeier/log-rank).Conclusions:Over half AITL cases might be confused in diagnosis for certain conditions without mutation data.Targeted exome sequencing with a comprehensive panel is crucial to detect both hot-spot and rare mutation variants for RHOA and IDH2 and other recurrent mutated genes in addition to TET2 and DNMT3A.EBER highdensity independently indicated adverse survival.

A case of colon perforation due to enteropathy-associated T-cell lymphoma

Enteropathy-associated T-cell lymphoma (EATL) is an extremely rare disease, which is often related to gluten-sensitive enteropathy. It is an uncommon intestinal lymphoma with very poor prognosis and high mortality rate. In the absence of specific symptoms or radiological findings, it is difficult to diagnose early. Major complications of EATL have been known as intestinal perforation or obstruction, and only 5 cases of EATL are reported in South Korea. In this study, we report a case of 71-year-old male with symptoms of diarrhea, which later it progressed into cancer perforation of the colon. The initial colonoscopic findings were normal and computed tomography scan demonstrated a segmental wall thickening of the distal ascending colon with nonspecific multiple small lymphnodes, along the ileocolic vessels, but no signs of mass or obstruction. The histologic findings of resected specimen confirmed EATL type II. Patient expired two weeks after the operation. Therefore, we emphasize the need of random biopsy in the presence of normal mucosa appearance on colonoscopy for the early diagnosis of EATL.

Two Cases of Tuberculosis Manifesting as Cutaneous Solitary Mass in Patients with Adult T-Cell Leukemia/Lymphoma

Tuberculosis (TB) is a major public health problem worldwide and a large number of fatal cases are still reported. Immunocompetent individuals are naturally susceptible to TB, and immunocompromised patients have a greater risk of infection. Although patients with adult T-cell leukemia/lymphoma (ATL) are in an immunosuppressed condition, there is only one reported case of TB accompanied with ATL in the English- language literature in the field of dermatology. Here, we report two patients with chronic-type ATL infected with TB manifesting as cutaneous solitary masses. Case 1 was a 58-year-old woman diagnosed with lumbar abscess with pulmonary TB. Case 2 was an 84-year-old woman diagnosed with tuberculous lymphadenitis in the left cervical region. It is important to raise the differential diagnosis of TB and perform tissue culture for acid-fast bacilli as well as Interferon-Gamma release assay test when dermatologists encounter mass lesions in patients with ATL.

Early colon cancer with enteropathy-associated T-cell lymphoma involving the whole gastrointestinal tract:A case report

BACKGROUND Enteropathy-associated T-cell lymphoma(EATL)is a rare invasive lymphoma derived from gastrointestinal epithelial T lymphocytes.EATL involving the whole gastrointestinal tract accompanied with early colon cancer is extremely rare.CASE SUMMARY We present the case of a 67-year-old man with diarrhea for more than 5 mo whose colonoscopy in another hospital showed multiple colonic polyps,which indicated moderate to severe dysplasia and focal early cancer.Therefore,he was referred to our hospital for further endoscopic treatment.Colonoscopy after admission showed that the mucosa of the terminal ileum and the entire colon were slightly swollen and finely granular.Endoscopic mucosal resection was performed for colonic polyps located in the liver flexure of the colon and descending colon,respectively.Histopathological findings revealed diffuse infiltration of mediumsized lymphoid cells in the colonic mucosa and visible lymphoepithelial lesions.The histopathology of the polyp in the descending colon indicated moderately differentiated adenocarcinoma limited to the mucosa with negative resection margins.Additionally,immunohistochemical analysis showed positive staining for CD7 and CD8.Therefore,we arrived at a diagnosis of EATL with early colon cancer.Subsequently,the patient was transferred to the hematology department for chemotherapy.The patient’s diarrhea was not significantly relieved after receiving chemotherapy,and he ultimately died of severe myelosuppression.CONCLUSION EATL should be considered in unexplained chronic diarrhea.EATL progresses rapidly with a poor prognosis,especially when accompanied with early colon cancer.