Histopathological characterization of the neuroglial tissue in ovarian teratoma associated with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis

Anti-NMDA receptor autoimmune encephalitis associated with ovarian teratoma: A case series and literature review

Autoimmune encephalitis is a group of disorders characterized by symptoms of dysfunction of the limbic and extra-limbic systems that occur in association with antibodies against intracellular antigens, synapses, or proteins located on the surface of nerve cells. Anti-NMDA (N-methyl-D-aspartate) receptor encephalitis was first described in 2007 and has become one of the most commonly recognized autoimmune encephalitides. The disease is predominantly female (81%) and affects young patients (37% <18 years old, 95% <45 years old), with up to 58% of women over 18 years old having ovarian teratoma. Clinical symptoms of anti-NMDA receptor encephalitis include psychiatric disorders (anxiety, agitation, bizarre behavior, hallucinations, delusions, and memory impairment); seizures and epileptic states; and other neurologic symptoms (muscle tone abnormalities, eye movement disorders, and central ventilatory disorders). Diagnosis of this condition can be difficult due to the non-specific nature of the symptoms, often leading to delays in appropriate treatment. Early diagnosis and timely treatment of anti-NMDA receptor encephalitis, especially in young women with ovarian teratoma, has significantly improved the chances of full recovery and improved reproductive health outcomes for patients.

Central nervous tissue in ovarian mature teratoma: A neuropathological study of 101 resected tumors

Ovarian mature teratomas frequently contain central nervous system (CNS) tissue that often exhibits a variety of neuropathologic alterations. The author systematically examined the changes seen in CNS tissue from a series of 251 cases of resected ovarian mature teratomas. A total of 101 (40.2%) samples contained CNS tissue in varying amounts. The principal pathologic findings in the CNS tissue from ovarian mature teratomas were as follows: (i) CNS tissue tended to form a relatively thin, undulating, plate-like structure that comprised the walls or septa of cystic tumors; (ii) most neurons were small or medium sized, and no CD34-positive "ramifying cells" were observed; (iii) cytoplasmic processes of some astrocytes closely surrounded the walls of capillaries, suggesting formation of a blood-brain barrier; (iv) some ependymal cells exhibited a columnar shape and showed a pseudostratified arrangement, and these cells extended thick basal cytoplasmic processes into the neuropil; (v) a few choroid plexus epithelial cells showed melanin deposition, tubular transformation, or oncocytic changes; (vi) hamartoma-like hyperplasia of arachnoid cells was noted beneath skin tissue; (vii) some CNS tissue showed formation of cerebral cortical structures exhibiting "gyration" with incompletely layered structures, and disruption of the glia limitans with spillage of cortical tissue into the "subarachnoid" space was also observed; and (viii) in the well-formed cerebellar cortex, dendrites of Purkinje cells exhibited varied dysmorphic changes. These neuropathologic observations should lead to a deeper understanding of the pathogenesis of various lesions in the brain.

Association of ovarian teratoma with anti-N-methyl-D-aspartate receptor encephalitis: a case report and narrative review

BACKGROUND

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a potentially life-threatening autoimmune disorder which is strongly associated with ovarian teratomas in young female patients. The primary aim is to highlight the importance of considering NMDAR encephalitis in the differential diagnosis of young female patients presenting with acute or subacute neuropsychiatric symptoms, especially when accompanied by ovarian teratomas.

CASE DESCRIPTION

This case report and literature review detail the presentation, diagnosis, and treatment of a 35-year-old G4P3 Indigenous woman who initially presented with neuropsychiatric symptoms and fever, having a history of extensive drug and alcohol use. Misdiagnosed initially, the patient's lack of response to standard treatments led to further investigations, revealing paraneoplastic anti-NMDAR encephalitis secondary to a left ovarian teratoma. The report examines the treatment regimen followed, including prednisolone, intravenous immunoglobulin, rituximab injections, and laparoscopic bilateral salpingo-oophorectomy.

CONCLUSIONS

This case underscores the critical need for increased clinical vigilance for anti-NMDAR encephalitis in patients, particularly young females, presenting with neuropsychiatric symptoms and potential ovarian teratomas. The literature review accompanying the case report provides valuable insights into the presentation, diagnosis, and management of this complex condition. Lastly, this study emphasised the diagnostic challenges inherent in paraneoplastic neuropsychiatric syndromes, advocating for a multidisciplinary approach in similar clinical scenarios.

Mechanisms of immune tolerance breakdown in paraneoplastic neurological syndromes

Paraneoplastic neurological syndromes (PNS) are rare autoimmune disorders triggered by the presence of a cancer. The autoimmunity is herein directed against proteins expressed both in the tumor and in the nervous system, namely the onconeural antigens, against which are directed specific autoantibodies, each of them characterizing a neurological syndrome. The mechanisms of the immune tolerance breakdown in PNS leading to the production of specific autoantibodies directed against the nervous system and leading to the immune attack begins to be explained. Each syndrome is associated with a specific histo-molecular subtype of tumor suggesting a link between the PNS genesis and oncogenesis. The expression of the onconeural antigen by these tumors is insufficient to explain the immune tolerance breakdown. In some PNS tumors, alterations of the antigen have been identified: mutations, gene copy number variation and overexpression of transcript and protein. But in others PNS, no such molecular alterations of the onconeural antigens have been demonstrated. In these cases, other mechanisms of neoantigen generation that may be involved remain to be deciphered. Cancer outcomes of PNS tumors are also characterized by the high frequency of lymph node metastasis at diagnosis. At the primary tumor site, the antitumor immune reaction seems to be particularly intense and characterized by a prominence of B-cell and Ig-secreting plasma cells that may generate the autoantibody secretion. The immune control mechanisms leading to such organization of the immune attack are not known to date. Renewed research efforts are thus needed to better understand the mechanism of immune tolerance breakdown in each PNS and determine potential targets to meet the therapeutic challenges posed by these rare disorders.

Anti-NMDAR encephalitis with delayed ovarian teratoma in a young woman: a case report with 5 years of follow-up

BACKGROUND

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder with a variety of clinical manifestations. It has been established that anti-NMDAR encephalitis may be related to ovarian teratoma in female patients. However, a considerable number of patients have no obvious evidence of ovarian teratoma during the onset of the disease.

CASE

A 25-year-old previously-healthy female experienced a series of acute symptoms within two days, including confusion, disorientation, short-term memory loss, auditory hallucinations, abnormal behavior, refractory status epilepticus, etc. Her brain MRI and abdominal imaging showed no definite abnormality while her electroencephalogram exhibited the presence of low to moderate amplitude sharp, spike, and multi-spike waves. Serum and cerebrospinal fluid tests yielded positive results for anti-NMDAR antibodies. However, an ultrasound scan failed to identify an ovarian teratoma. Consequently, the diagnosis of anti-NMDAR encephalitis without teratoma was made after 4 days onset. After the plasma exchange and immunoglobulin therapy, her neurological symptoms improved and obtained a clinical cure. In the next eight months of follow-up, the patient accidentally touched a lump in the lower abdomen without any symptoms, and abdominal ultrasound and CT scan revealed a left ovarian tumor. Then she underwent left ovarian teratoma resection surgery and histopathology showed a mature cystic teratoma with neural components. The patient continued to receive five years of follow-up, and her condition remained stable without any recurrence, except that there had been a low titer of anti-NMDAR antibody in her serum.

CONCLUSION

Our case demonstrated the importance of long-term follow-up for female patients with anti-NMDAR encephalitis, since anti-NMDAR encephalitis-associated ovarian teratomas may develop in a delayed manner, even without any symptoms.

Surgical procedures and plasma exchange for ovarian teratoma-associated anti-N-methyl D-aspartate receptor encephalitis: a case report and review of literature

We reported a case of ovarian teratoma-associated Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis with recurrent epileptic seizures and disturbance of consciousness. Although surgical excision of the tumor remains the established standard of care, unlike other reported cases, the patient exhibited limited response to early oophorocystectomy, as well as IVIG and steroid therapy; however, a favorable response was observed with Plasma exchange (PE) initiated on postoperative day 12. Literature review revealed no definite recommended surgical extent for ovarian teratomas, and outstanding improvement in patients with anti-NMDAR encephalitis following PE. Our case raises the question regarding the optimal surgical extent for tumor resection, necessitating careful consideration when deciding between oophorectomy and adnexectomy as the preferred surgical procedure for anti-NMDAR encephalitis in female teens and adults. Furthermore, for refractory patients who fail to respond following tumor resection, PE can be performed early instead of immediately initiating second-line therapy.

Risk of epilepsy in gonadal teratoma: a nationwide population-based study

Epilepsy is a common neurological disease. Systemic tumors are associated with an increased risk of epileptic events. Paraneoplastic encephalitis related to gonadal teratoma is frequently accompanied by seizures and life-threatening status epilepticus (SE). However, the risk of epilepsy in gonadal teratoma has not been studied. This study aims to investigate the relationship between epileptic events and gonadal teratoma. This retrospective cohort study used the Korean National Health Insurance (KNHI) database. The study population was divided into two study arms (ovarian teratoma vs. control and testicular teratoma vs. control) with 1:2 age and gender-matched control groups without a history of gonadal teratoma or other malignancy. Participants with other malignancies, neurologic disorders, and metastatic brain lesions were excluded. We observed the occurrence of epileptic events during the observation period (2013-2018) and investigated the risk of epileptic events in each gonadal teratoma group compared to controls. In addition, the influence of malignancy and tumor removal was investigated. The final analysis included 94,203 women with ovarian teratoma, 2314 men with testicular teratoma, and controls. Ovarian teratoma is associated with a higher risk of epilepsy without SE (HR, 1.244; 95% CI 1.112-1.391) and epilepsy with SE (HR, 2.012; 95% CI 1.220-3.318) compared to the control group. The risk of epilepsy without SE was higher in malignant ovarian teratoma (HR, 1.661; 95% CI 1.358-2.033) than in benign (HR, 1.172; 95% CI 1.037-1.324). Testicular teratoma did not show significant relations with epileptic events. The risk of epileptic events showed a tendency to decrease after removing the ovarian teratoma. This study found that ovarian teratoma is associated with a higher risk of epileptic events, especially in malignant tumors, whereas testicular teratoma did not show significant differences in epileptic events compared to the control group. This study adds to the current understanding of the association between gonadal teratoma and epileptic events.

Ovarian Teratoma-Related Paraneoplastic Neurological Syndromes

Paraneoplastic neurological syndromes (PNSs) are a group of neurological disorders triggered by an underlying remote tumor. Ovarian teratoma (OT) is the most common histologic type of germ cell tumor in females. The most common PNSs associated with OT is anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. However, with the increasing number of new antibodies reported over the last decade, the clinical spectrum of OT-related PNSs is also expanding. Our knowledge of OT-related PNSs is still far from complete. Here, we provide a comprehensive review of the most recent findings in the field of OT-related PNSs, with a particular focus on their clinical and pathological characteristics. Overall, the description of neuronal antibodies in PNSs associated with OT strongly suggests that antibodies may be responsible for the clinical symptoms in some cases. OT-related PNSs are associated with various clinical manifestations, including anti-NMDAR encephalitis, limbic encephalitis, encephalomyelitis, progressive cerebellar syndrome and opsoclonus-myoclonus syndrome. The pathological characteristics of the OT suggest that the mechanism of PNSs is probably due to heteromorphic neurons in the tumor tissue, the ectopic expression of the antigens in neural tissue within the teratomas and patients' unusual immune response. Despite the severity of the neurological syndromes, most patients with OT-related PNSs showed good neurologic response to early tumor resection combined with immunotherapy. To further advance the management of OT-related PNSs, additional studies are needed to explore this complex topic.

Anti-NMDA Receptor Encephalitis: Retrospective Analysis of 15 Cases, Literature Review, and Implications for Gynecologists

Background

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a rare form of autoimmune encephalitis caused by anti-NMDA receptor antibodies. This disease mainly affects women of childbearing age and is commonly associated with ovarian teratoma. However, the relationship between anti-NMDA receptor encephalitis and ovarian teratoma and the role of anti-NMDA receptor antibody in the relationship remain unclear.

Objectives

This study aimed to describe 15 cases of anti-NMDA receptor encephalitis (5 with ovarian teratoma), review literature, and reinforce the gynecologist's knowledge of this disorder.

Methods

Clinical data of 15 patients from January 2015 to December 2020 admitted to The Second Hospital of Hebei Medical University were collected and analyzed. The diagnosis of anti-NMDA receptor encephalitis was based on the presence of anti-NMDA receptor antibodies in cerebrospinal fluid (CSF) and/or serum. Laparoscopic teratoma removal was performed in patients with ovarian teratoma. All patients had received immunotherapy. In addition, a review of the literature was performed to reinforce the gynecologist's knowledge of this disorder.

Results

A total of 15 patients with anti-NMDA receptor encephalitis were screened, of whom 5 patients were confirmed with ovarian teratoma by pathology. The most common symptoms of anti-NMDAR encephalitis with teratoma are fever (5/5, 100%), seizure (5/5, 100%), mental and behavioral disorders (4/5, 80%), and decreased consciousness (4/5, 80%). Conversely, the most common symptoms of patients without teratoma were neuropsychiatric symptoms, including headache (6/10, 60%) and mental and behavioral disorders (7/10, 70%). All patients underwent immunotherapy, including steroids, intravenous immunoglobulin (IVIG), plasma exchange, and cyclophosphamide, and 4 out of 5 patients with ovarian teratomas underwent surgical treatment. All patients had a good outcome after systemic, surgical, and immunotherapy treatment. No patient who underwent surgical treatment developed a recurrence. Conversely, 2 of 10 patients without teratoma developed an anti-NMDA receptor encephalitis recurrence.

Conclusions

Patients with anti-NMDA encephalitis show severe mental and neurological symptoms. Resection of teratoma is beneficial to the relief or disappearance of symptoms and has a good prognosis. This disorder should be fully recognized by gynecologists, who play an important role in diagnosis and treatment.

Benign ovarian teratoma in the dog with predominantly nervous tissue: A case report

Ovarian teratomas are rare neoplasms in female dogs, and they are characterised by the proliferation of tissues of embryonic origin. Most teratomas are benign, but a histological diagnosis is important for clinicians. The objective of this article is to describe a benign ovarian teratoma in a dog, which was found on the street and was appearing like pregnant. A veterinary inspection by palpation documented an enlarged abdomen with a mass of tough matter located on the right side in the abdominal-pelvic part. An ultrasound examination presumed neoplastic mass in region of ovary. A bilateral ovariohysterectomy was performed and the subsequent histological evaluation revealed a benign ovarian teratoma with a histochemically and immunohistochemically verified nervous tissue. After one year, no distant metastases were found and the dog was recognised as being clinically healthy without problems. On the basis of the ultrasonography diagnostics and histopathological analyses, we have demonstrated the occurrence of a benign ovarian teratoma in a dog.

Contemporary advances in anti-NMDAR antibody (Ab)-mediated encephalitis

The study of antibody (Ab)-mediated encephalitis has advanced dramatically since the discovery of antibodies directed against the N-methyl-D-aspartate receptor (NMDAR) in association with a unique neuro-psychiatric syndrome, over a decade-and-a-half ago. Anti-NMDAR Ab-mediated encephalitis now represents the most well characterised form of autoimmune encephalitis. The disease most commonly manifests in young women, but all ages and both sexes can be affected. Autoantibodies may arise in the context of two well-recognised disease triggers in a proportion of patients, and ultimately facilitate NMDAR displacement from synapses. Various CSF cytokines, chemokines, and other molecules have been explored as candidate biomarkers but are limited in sensitivity and specificity. The clinical spectrum is diverse, with evolution and a combination of neuro-psychiatric abnormalities at disease nadir common. Anti-NMDAR Ab-mediated encephalitis is immunotherapy responsive, and a near-majority ultimately acquire a broadly favourable clinical outcome. The diagnosis, and more particularly, the management of the disease can still hold considerable challenges. Moreover, well-defined biomarkers remain elusive. The present review will therefore delineate pathogenic and clinical advances to date in anti-NMDAR antibody-mediated encephalitis.

The Association of Ovarian Teratoma and Anti-N-Methyl-D-Aspartate Receptor Encephalitis: An Updated Integrative Review

Ovarian teratomas are by far the most common ovarian germ cell tumor. Most teratomas are benign unless a somatic transformation occurs. The designation of teratoma refers to a neoplasm that differentiates toward somatic-type cell populations. Recent research shows a striking association between ovarian teratomas and anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, a rare and understudied paraneoplastic neurological syndrome (PNS). Among teratomas, mature teratomas are thought to have a greater relevance with those neurological impairments. PNS is described as a neurologic deficit triggered by an underlying remote tumor, whereas anti-NMDAR encephalitis is characterized by a complex neuropsychiatric syndrome and the presence of autoantibodies in cerebral spinal fluid against the GluN1 subunit of the NMDAR. This review aims to summarize recent reports on the association between anti-NMDAR encephalitis and ovarian teratoma. In particular, the molecular pathway of pathogenesis and the updated mechanism and disease models would be discussed. We hope to provide an in-depth review of this issue and, therefore, to better understand its epidemiology, diagnostic approach, and treatment strategies.

Research progress in teratoma-associated anti-N-methyl-D-aspartate receptor encephalitis: The gynecological perspective

AIM

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is one of the autoimmune encephalitis, which often occurs in children and young adults, especially in young women. In addition to viral infection, teratoma is an important causative factor. Anti-NMDAR encephalitis is well known to neurologist. However, this is less well known to gynecologists, who may have a decisive role in etiological management. Therefore, from the perspective of gynecologists, we provide an overview of the relationship between the encephalitis and ovarian teratoma, the clinical features and treatment of this disease, and prognosis of pregnant women with this encephalitis.

METHODS

We searched the PubMed database using the search terms in various combinations "teratoma," "dermoid cyst," "ovary," "ovarian," "anti-NMDAR encephalitis," and "N-methyl-D-aspartate receptor."

RESULTS

According to the current literature, the mechanism of anti-NMDAR encephalitis is probably due to the ectopic expression of the NMDAR in the teratomas tissue. The disease has a high mortality rate if not treated promptly and effectively. An important way to improve patients' outcome is to remove the ovarian tumor in time. Pregnant women are also at risk of developing anti-NMDAR encephalitis during pregnancy. The fetal outcome is usually better in patients with mid- to late-pregnancy onset than in early pregnancy, and patients are often able to maintain their pregnancies into late pregnancy.

CONCLUSION

Young women with sudden onset of abnormal psychiatric behavior should be actively screened for ovarian tumors and, if confirmed to be teratoma-associated anti-NMDAR encephalitis, should undergo gynecologic surgery as early as possible, which can help improve their prognosis.

CT and MRI characteristics of ovarian mature teratoma in patients with anti-N-methyl-D-aspartate receptor encephalitis

PURPOSE

The purpose of this study was to determine the computed tomography (CT) and magnetic resonance imaging (MRI) characteristics of ovarian mature teratoma in patients with anti-N-methyl-d-aspartate receptor encephalitis (NMDAR-E).

MATERIALS AND METHODS

A total of 125 women (mean age, 40.9±17.8 [SD] years; age range: 12-85 years) with 146 histopathologically or radiologically proven ovarian mature teratomas who underwent preoperative CT and MRI examinations were retrospectively included. Eight patients with 11 teratomas had NMDAR-E, whereas 117 patients with 135 teratomas did not have NMDAR-E. CT and MRI examinations were retrospectively reviewed and teratomas in patients with NMDAR-E were compared to those in patients without NMDAR-E. Comparisons were performed using Mann-Whitney U test or Fisher exact test.

RESULTS

In patients with NMDAR-E, maximum diameter of teratomas (26.1±9.3 [SD] mm), prevalence of teeth/calcification (36%) and rate of occupation by fat components (26%) were lower than those in patients without NMDAR-E (67.0±37.6 [SD] mm [P<0.01]; 75% [P<0.05]; and 65%[P<0.01], respectively). More than 75% of space was occupied by fat components in 76/135 teratomas (56%) in patients without NMDAR-E, whereas this was not observed in any teratoma in patients without NMDAR-E.

CONCLUSION

By comparison with teratomas in patients without NMDAR-E, teratomas in patients with NMDAR-E are smaller, have few teeth/calcification, and the amount of space occupied by fat components is smaller.

HLA-A and HLA-DRB1 may play a unique role in ovarian teratoma-associated anti-N-methyl-D-aspartate receptor encephalitis

BACKGROUND

Ovarian teratoma-associated anti-N-methyl-D-aspartate receptor encephalitis (NMDAR-E) is a severe autoimmune neurological disorder, and the influence of teratoma-induced autoantibodies on the pathogenesis remains unclear.

METHODS

Ovarian teratoma tissues were collected from teratoma patients with and without NMDAR-E. Proteins were extracted and then analyzed using iTRAQ-coupled LC-MS/MS, which was followed by bioinformatics analysis. Candidate proteins were verified by Western blotting and immunohistochemistry.

RESULTS

In total, 36 differentially expressed proteins (DEPs) were identified between the control group and NMDAR-E group, and the bioinformatics analysis revealed that the DEPs were mainly involved in immune-related pathways, especially HLA-A and HLA-DRB1. The western blotting results for HLA-A and HLA-DRB1 were consistent with the results of the iTRAQ analysis. Additionally, the immunohistochemical data revealed that the aggregation of HLA-A (+) and HLA-DRB1 (+) cells was more apparent in the teratoma tissues of NMDAR-E patients compared with that in the tissues of controls.

CONCLUSION

Our investigation indicated that HLA-A and HLA-DRB1 might be involved in mediating ovarian teratoma-associated NMDAR-E. These findings provide new insights into the pathophysiological mechanisms and provide information for the functional exploration of proteins in the future.

Ovarian and non-ovarian teratomas: a wide spectrum of features

Teratoma is a germ cell tumor (GCT) derived from stem cells of the early embryo and the germ line. Teratoma is the most common neoplasm of the ovaries and is usually diagnosed easily using imagings by detecting fat components. However, there are various histopathological types and the imaging findings differ according to the type. Teratoma usually occurs in the gonads or in the midline due to migration of primordial germ cells during development. The clinical course of teratomas depends on the age of the patient, histological type, and anatomical site. Sometimes teratomas show unusual manifestations, such as mature teratoma without demonstrable fat components, torsion, rupture, growing teratoma syndrome, anti-N-methyl-D-aspartate receptor encephalitis, and autoimmune hemolytic anemia. For all of these reasons, teratomas demonstrate a wide spectrum of imaging features and radiologists should be familiar with these variabilities. The present article aims to introduce a model encompassing types of GCTs based on their developmental potential, and to review several histopathological types in various anatomical sites and unusual manifestations of teratomas, with representative imaging findings.

Co-expression of NMDA-receptor subunits NR1, NR2A, and NR2B in dysplastic neurons of teratomas in patients with paraneoplastic NMDA-receptor-encephalitis: a retrospective clinico-pathology study of 159 patients

Objective

To comprehensively describe the pathological features of neurons in patients with ovarian teratomas and paraneoplastic anti-NMDAR encephalitis (anti-NMDARE), emphasizing on NMDA-receptor expression and infiltrating lymphocytes.

Methods

A retrospective study was performed in a large series of 159 patients from the West China Hospital. We retrospectively identified 12 patients with paraneoplastic anti-NMDARE (11 case with ovarian teratomas and 1 case with mixed germ cell tumor), which were compared to 35 patients with teratomas and no encephalitis and to 147 patients with anti-NMDARE and no evidence for tumors. Patient history and outcome were reviewed from the clinical charts and compared between all three groups. Histopathological examination, including double-immunofluorescence of NMDAR subunits and IgG was performed in all teratoma tissues. Magnetic Luminex Assay Human Premixed Multi-Analyte Kit was performed to investigate cytokines profile of CSF.

Results

Patients with paraneoplastic anti-NMDARE had a more severe clinical presentation, i.e. they required more mechanical ventilation and intensive care (p < 0.001). Though immunotherapy was initiated earlier in this group, repeated intravenous immunoglobulin administration (IVIG) was more common (p = 0.002) and with higher cerebrospinal fluid (CSF) antibody titres (p = 0.004). Following tumor resection, the outcome did not differ between groups. A peculiar population of floating-frog like dysplastic neurons were observed only in teratomas of patients with paraneoplastic anti-NMDARE, co-expressing NR1, NR2A, NR2B subunits and IgG. Also, CD20 positive B-cells were more common in anti-NMDARE teratomas. In CSF of paraneoplastic anti-NMDARE patients, TNF-α, IL-10 and GM-CSF concentrations were higher than in negative symptom control and VEGF-A and IL-1a were lower than in anti-NMDARE patients (0.25 < p < 0.05).

Conclusions

Patients with teratomas and paraneoplastic anti-NMDARE revealed a cellular population of dysplastic neurons co-expressing NMDAR subunits, which were the potential source of autoantigens triggering anti-NMDARE. Some inflammatory cytokines may be involved in pathogenesis of paraneoplastic anti-NMDARE.

Clinicopathological characteristics of dysplastic teratomous neuroglia with anti-N-methyl-d-aspartate receptor encephalitis

In this study, we investigated whether unique pathological characteristics exist in teratomas that can trigger autoimmune anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. We compared a case of retroperitoneal teratoma associated with anti-NMDAR encephalitis and four control cases. The encephalitis-positive case showed that (i) more dysplastic neuroglia with higher Ki-67 labeling index values than the control cases, which met the diagnostic criteria of astrocytoma, (ii) the NMDAR subunit NR1 was expressed more abundantly in neuroglial tissue where many neuroglial cells co-expressed glial fibrillary acidic protein (GFAP) and NR1 and formed abnormally large cellular masses, (iii) intense NR1 expression occurs in squamous epithelium near neuroglial tissue and lymphocyte infiltration. This study showed that dysplastic neuroglial tissue resembling central nervous system tumors, which might promote autoimmunity, distinguished the case with NMDAR encephalitis from the controls. Additionally, abnormal expression of NR1 occurs in non-neural tissues and could be triggered by inflammation and participate in autoimmunity.

Surgical outcomes in patients with anti-N-methyl D-aspartate receptor encephalitis with ovarian teratoma

BACKGROUND

Anti-N-methyl-D-aspartate receptor encephalitis is an autoimmune encephalitis mediated by anti-N-methyl-D-aspartate receptor antibodies. Ovarian teratoma is closely related to anti-N-methyl-D-aspartate receptor encephalitis. However, the optimal treatment remains unknown, and strategies used for the diagnosis and therapy, including surgical intervention of ovarian teratoma, are debatable.

OBJECTIVE

The objective of the study was to study the clinical features of anti-N-methyl-D-aspartate receptor encephalitis with ovarian teratoma to further understand the disease.

STUDY DESIGN

This single-center prospective study included patients with anti-NMDAR encephalitis with ovarian teratoma from 2011 to 2016 who were admitted to Peking Union Medical College Hospital, Beijing, and discussed the clinical characteristics, treatment, and prognosis of the disease. The diagnosis of anti-N-methyl-D-aspartate receptor encephalitis was established preoperatively by identifying anti-N-methyl-D-aspartate receptor antibodies in the cerebrospinal fluid. Ovarian teratomas were suspected preoperatively by pelvic ultrasound and were diagnosed pathologically after laparoscopic detection and ovarian tumor resection. All patients were treated with first-line immunotherapy (steroids, intravenous immunoglobulin, and plasmapheresis), and when the therapy failed, they were treated with second-line immunotherapy (cyclophosphamide and rituximab). All patients were followed up regularly, and N-methyl-D-aspartate receptor antibodies, pelvic ultrasound, and neurological condition were monitored. Neurological symptoms were assessed using the modified Rankin Scale.

RESULTS

A total of 108 female patients with anti-N-methyl-D-aspartate receptor encephalitis were screened, of whom, 29 patients (26.9% of 108; mean age ± SD, 23.14 ± 6.59 years) had pathologically confirmed ovarian teratoma. The incidence of fever, decreased consciousness, arrhythmia, central hypoventilation, ventilator-assisted respiration, and intensive unit care (75.9%, 65.5%, 27.6%, 55.2%, 55.2%, and 58.6%, respectively) were significantly higher in patients with ovarian teratoma than in those without ovarian teratoma. The modified Rankin Scale at the acute onset in those 29 patients was 4.11 ± 1.20, which was also much higher than that in patients without ovarian teratoma (3.58 ± 1.08). Of the 29 patients with ovarian teratoma, 22 (75.9%) underwent laparoscopy during the acute onset of neurological symptoms. The mean diameter of the tumor was 4.61 ± 3.41 cm (SD), and the smallest tumor was only 1 cm in the unilateral ovary. All other cysts, except 4 bilateral cysts (13.8%), were unilateral. Only 1 patient was diagnosed pathologically with immature ovarian teratoma, while others had benign ovarian teratomas. In all, 28 patients (96.5%) had a good outcome (modified Rankin Scale ≤2) and 1 died. In the follow-up visit (mean duration, 37.69 months), the relapse rate of encephalitis in patients with ovarian teratoma undergoing laparoscopic cystectomy was 14.6%, whereas for those without ovarian teratoma, the relapse rate was 33.3%. The removal of ovarian teratoma was associated with reduced risk of relapse.

CONCLUSION

Patients having anti-N-methyl-D-aspartate receptor encephalitis with ovarian teratomas tend to present more severe neurological conditions. The diameter of the tumor in these patients is not very large and could be as small as 1 cm, and thus, careful exploration should be considered during surgery. Most of the ovarian teratomas in patients with anti-N-methyl-D-aspartate receptor encephalitis are mature. Early operative treatment is safe and effective because it is associated with reduced risk of relapse and complete recovery.

Immunopathological characterization of ovarian teratomas associated with anti-N-methyl-D-aspartate receptor encephalitis

Encephalitis with anti-NMDAR antibodies (NMDAR-E) is a severe autoimmune neurological disorder, defined by a clinical presentation of encephalitis and the presence of IgG targeting the GluN1 subunit of NMDA receptors in the CSF. An underlying ovarian teratoma is commonly associated with this autoimmune disease suggesting a role of the tumor in immunopathogenesis. In this study, we characterized the salient histopathological features of 27 ovarian teratomas associated with NMDAR-E (3 immature and 24 mature teratomas) and 40 controls without associated encephalitis. All but one NMDAR-E-associated teratomas contained a nervous tissue component, while less than 40% of control teratomas did (p < 0.001). GluN1 expression by teratomatous nervous tissue seemed to be more often glial in NMDAR-E teratomas than in control teratomas (73% vs. 29%, p < 0.05). Strikingly, 3 out of 24 NMDAR-E-associated mature teratomas contained neuroglial tissue exhibiting histopathological features of central nervous system neuroglial tumor, while such glioma-like features are exceptionally described in the literature on ovarian teratomas. Moreover, NMDAR-E associated teratomas differed from sporadic ovarian teratomas by consistent and prominent infiltration of the nervous tissue component by immune cells, comprised of T- and B-cells and mature dendritic cells organized in tertiary lymphoid structures, with IgG and IgA deposits and plasma cells in close contact to the neuroglial tissue.

These data demonstrate an association between massive infiltration of NMDAR-E-associated teratomas by immune cells and particular glial features of its neuroglial component, suggesting that this glial tissue might be involved in triggering or sustaining the anti-tumor response associated with the auto-immune neurological disease.