Predictive capacity of a miRNA panel in identifying teratoma in post-chemotherapy consolidation surgeries

Objectives

To investigate the utility of a novel serum miRNA biomarker panel to distinguish teratoma from nonmalignant necrotic/fibrotic tissues or nonviable tumours in patients with NSGCT undergoing post-chemotherapy consolidation surgery.

Patients and methods

We prospectively collected pre-surgical serum samples from 22 consecutive testicular NSGCT patients with residual NSGCT after chemotherapy undergoing post-chemotherapy consolidation surgery. We measured serum miRNA expression of four microRNAs (miRNA-375, miRNA-200a-3p, miRNA-200a-5p and miRNA-200b-3p) and compared with pathologic findings at time of surgery. Receiver operating characteristic (ROC) curves were performed to assess the ability of these miRNA to differentiate between teratoma and necrosis or viable malignancy.

Results

Twenty-two patients with NSGCT were split into two groups based on pathology at time of post-chemotherapy consolidation surgery (teratoma group vs. necrosis/fibrosis/viable tumour group, i.e., NFVT). Patients with teratoma were older at diagnosis compared with those patients with NFVT (median age 28.7 vs. 23.9). Patients with NFVT were more likely to have embryonal carcinoma in their primary tumour (81.8% vs. 27.3%; p = 0.01). The majority of patients in both groups were stage III (63.6% vs. 72.7%). In this analysis, none of the miRNAs had good sensitivity or specificity to predict teratoma. There was no significant association between the expression levels of the miRNAs and the presence of teratoma. There was no statistically significant correlation between any of the miRNAs and teratoma size.

Conclusion

This novel miRNA panel (miRNA-375, miRNA-200a-3p, miRNA-200a-5p and miRNA-200b-3p) did not distinguish teratoma from nonmalignant necrotic/fibrotic tissues or nonviable tumours in patients with NSGCT undergoing post-chemotherapy consolidation surgery.

Oropharyngeal teratoma: A case presentation and review of literature

Teratomas are true neoplasms derived from the three germ layers. They are relatively rare tumours. They present in the sacrococcygeal region, gonads and retroperitoneum commonly. We present the report of a 5-month-old infant who presented with a prolapsing oropharyngeal teratoma and literature review.

The Tumorigenic Potential of Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) are currently evaluated for clinical applications due to their proliferation and differentiation capacities, raising the need to both assess and enhance, the safety of hPSC-based treatments. Distinct molecular features contribute to the tumorigenicity of hPSCs, manifested in the formation of teratoma tumors upon transplantation in vivo. Prolonged in vitro culturing of hPSCs can enhance selection for specific genetic aberrations, either at the chromosome or gene level. Some of these aberrations are tightly linked to human tumor pathology and increase the tumorigenic aggressiveness of the abnormal cells. In this perspective, we describe major tumor-associated risk factors entailed in hPSC-based therapy, and present precautionary and safety measures relevant for the development and application of such therapies.

Scrotal fetus in fetu in a newborn: A rare case report

Fetus in fetu is a rare phenomenon of infancy, separate from conjoined twins, teratomas, and acardiac twins. The pathogenesis is not well understood but has been theorized to originate from either the involution of a twin or the differentiation of a teratoma. While the majority of these are found in the retroperitoneum, the presence of a fetus in fetu within the scrotum is exceedingly rare. We present the diagnosis and management of a case of fetus in fetu in the scrotum of a newborn male including radiologic imaging and pathologic examination.

Morphological spectrum and molecular features of somatic malignant transformation in germ cell tumours

AIMS

Somatic malignant transformation (SMT) arising in germ cell tumours (GCTs) is an infrequent, but clinically relevant event. There is only limited knowledge on the morphological spectrum of SMT, and therapeutic management of these patients is poorly defined. In this work we revisit two consecutive case series (n=756) of GCTs. Clinicopathological data of SMT arising in GCT were determined, with focus on the histopathological spectrum, and molecular aspects were obtained by Fluorescence in situ Hybridization (FISH) and Next Generation Sequencing (NGS).

METHODS AND RESULTS

30 male patients (28 primary testicular, 2 primary extragonadal) were included. These patients represent 4% of GCT patients diagnosed in two institutes (University Hospital Zurich and IPO Porto). The most common SMT were adenocarcinoma (n=8), embryonic-type neuroectodermal tumours (ENETs, n=8) and rhabdomyosarcoma (n=6), but a wide range of challenging morphologies were depicted, including low-grade neuroglial tumour, adenosquamous carcinoma, neuroblastoma and neuroendocrine carcinoma. SMT was found in 15 primary tumour samples and in 27 metastatic samples of these 30 patients, the latter showing poorer overall-survival. Adenocarcinoma occurred only in metastasis post-chemotherapy and in one primary retroperitoneal GCT with SMT, but not in GCT of the testis. 12p gains were identified by FISH in all cases. NGS results were available in 6 patients. Clinical trials and/or targeted treatments based on the molecular profile of SMT were recommended in 4 patients.

CONCLUSIONS

SMT arising in GCTs represents a diagnostic challenge and should be confirmed by a specialized uropathologist. NGS based treatment recommendations may improve outcome of these patients.

"An eye for a tooth:" Orbital teratoma in an adult

A 27-year-old female presented with progressive prominence of her right eye since childhood. On examination, a pinkish mass filling the right orbit with no evidence of an eyeball was seen. She also had bilateral preauricular skin tags. Imaging revealed a mass with solid and cystic components in the right orbit, with a well-formed tooth in situ, suggestive of a teratoma. The tumor was removed and histopathology confirmed the diagnosis. Orbital teratoma in an adult is a rare presentation. The presence of preauricular skin tags in association with orbital teratoma is a new finding.

Cervical lymph nodes and ovarian teratomas as germinal centres in NMDA receptor-antibody encephalitis

Autoantibodies against the extracellular domain of the N-methyl-d-aspartate receptor (NMDAR) NR1 subunit cause a severe and common form of encephalitis. To better understand their generation, we aimed to characterize and identify human germinal centres actively participating in NMDAR-specific autoimmunization by sampling patient blood, CSF, ovarian teratoma tissue and, directly from the putative site of human CNS lymphatic drainage, cervical lymph nodes. From serum, both NR1-IgA and NR1-IgM were detected more frequently in NMDAR-antibody encephalitis patients versus controls (both P < 0.0001). Within patients, ovarian teratoma status was associated with a higher frequency of NR1-IgA positivity in serum (OR = 3.1; P < 0.0001) and CSF (OR = 3.8, P = 0.047), particularly early in disease and before ovarian teratoma resection. Consistent with this immunoglobulin class bias, ovarian teratoma samples showed intratumoral production of both NR1-IgG and NR1-IgA and, by single cell RNA sequencing, contained expanded highly-mutated IgA clones with an ovarian teratoma-restricted B cell population. Multiplex histology suggested tertiary lymphoid architectures in ovarian teratomas with dense B cell foci expressing the germinal centre marker BCL6, CD21+ follicular dendritic cells, and the NR1 subunit, alongside lymphatic vessels and high endothelial vasculature. Cultured teratoma explants and dissociated intratumoral B cells secreted NR1-IgGs in culture. Hence, ovarian teratomas showed structural and functional evidence of NR1-specific germinal centres. On exploring classical secondary lymphoid organs, B cells cultured from cervical lymph nodes of patients with NMDAR-antibody encephalitis produced NR1-IgG in 3/7 cultures, from patients with the highest serum NR1-IgG levels (P < 0.05). By contrast, NR1-IgG secretion was observed neither from cervical lymph nodes in disease controls nor in patients with adequately resected ovarian teratomas. Our multimodal evaluations provide convergent anatomical and functional evidence of NMDAR-autoantibody production from active germinal centres within both intratumoral tertiary lymphoid structures and traditional secondary lymphoid organs, the cervical lymph nodes. Furthermore, we develop a cervical lymph node sampling protocol that can be used to directly explore immune activity in health and disease at this emerging neuroimmune interface.

GP2-enriched pancreatic progenitors give rise to functional beta cells in vivo and eliminate the risk of teratoma formation

Human pluripotent stem cell (hPSC)-derived pancreatic progenitors (PPs) can be differentiated into beta-like cells in vitro and in vivo and therefore have therapeutic potential for type 1 diabetes (T1D) treatment. However, the purity of PPs varies across different hPSC lines, differentiation protocols, and laboratories. The uncommitted cells may give rise to non-pancreatic endodermal, mesodermal, or ectodermal derivatives in vivo, hampering the safety of hPSC-derived PPs for clinical applications and their differentiation efficiency in research settings. Recently, proteomics and transcriptomics analyses identified glycoprotein 2 (GP2) as a PP-specific cell surface marker. The GP2-enriched PPs generate higher percentages of beta-like cells in vitro, but their potential in vivo remains to be elucidated. Here, we demonstrate that the GP2-enriched-PPs give rise to all pancreatic cells in vivo, including functional beta-like cells. Remarkably, GP2 enrichment eliminates the risk of teratomas, which establishes GP2 sorting as an effective method for PP purification and safe pancreatic differentiation.

MicroRNAs in Differentiation of Embryoid Bodies and the Teratoma Subtype of Testicular Cancer

BACKGROUND

Testicular germ cell tumours (TGCTs) are the most frequent tumour type among young, adult men. TGCTs can be efficiently treated, but metastases of the teratoma subtype, for which there are no circulating biomarkers, represent a challenge.

MATERIALS AND METHODS

Global microRNA expression in teratoma tissue and embryoid bodies was assessed using next-generation sequencing. Levels of microRNAs identified as potential biomarkers were obtained from serum of patients with teratoma and matched healthy men.

RESULTS

We identified miR-222-5p, miR-200a-5p, miR-196b-3p and miR-454-5p as biomarker candidates from the tumour tissue and embryoid body screening but the expression of these microRNAs was very low in serum and not statistically different between patients and controls. miR-375-3p was highly expressed, being highest in patients with teratoma (p=0.012) but the levels of expression in serum from these patients and healthy controls overlapped. miR-371a-3p was not expressed in serum from patients with pure teratoma, only in patients with mixed tumours.

CONCLUSION

The microRNA profiles of the teratoma subtype of TGCT and embryoid bodies were obtained and assessed for candidate circulating biomarkers, but none with high sensitivity and specificity for teratoma were identified in our study. We conclude that neither the proposed teratoma marker miR-375-3p nor miR-371a-3p are suitable as circulating teratoma markers.

Ruptured Left Ovarian Teratoma Presenting as an Irreducible Right Inguinal Hernia

Teratomas of the ovary rarely present as inguinal hernias. Teratomas most commonly occur in the gonads or along with midline structures. Although the majority are asymptomatic, complications such as spontaneous rupture are known to occur. We present a previously unreported case of a ruptured ovarian teratoma presenting as an irreducible inguinal hernia. The patient underwent an open exploratory laparotomy with left oophorectomy, and the right inguinal hernia was repaired in the same setting with a separate inguinal incision.

Optimization of Thymidine Kinase-Based Safety Switch for Neural Cell Therapy

Cell therapies based on pluripotent stem cells (PSC), have opened new therapeutic strategies for neurodegenerative diseases. However, insufficiently differentiated PSC can lead to tumor formation. Ideally, safety switch therapies should selectively kill proliferative transplant cells while preserving post-mitotic neurons. In this study, we evaluated the potential of nucleoside analogs and thymidine kinase-based suicide genes. Among tested thymidine kinase variants, the humanized SR39 (SR39h) variant rendered cells most sensitive to suicide induction. Unexpectedly, post-mitotic neurons with ubiquitous SR39h expression were killed by ganciclovir, but were spared when SR39h was expressed under the control of the cell cycle-dependent Ki67 promoter. The efficacy of six different nucleoside analogs to induce cell death was then evaluated. Penciclovir (PCV) showed the most interesting properties with an efficiency comparable to ganciclovir (GCV), but low toxicity. We tested three nucleoside analogs in vivo: at concentrations of 40 mg/kg/day, PCV and GCV prevented tumor formation, while acyclovir (ACV) did not. In summary, SR39h under the control of a cell cycle-dependent promoter appears most efficient and selective as safety switch for neural transplants. In this setting, PCV and GCV are efficient inducers of cell death. Because of its low toxicity, PCV might become a preferred alternative to GCV.

An Approach to Nasopharyngeal Mass in Newborns: Case Series and Systematic Literature Review

OBJECTIVE

Congenital nasopharyngeal masses (CNMs) are rare. Presenting symptoms vary, and the differential diagnoses cover a wide spectrum of possibilities. As it is uncommon, most examples discussed in literature are described as case reports or series. Guidelines on CNM patient management do not exist. In this study, we present two (2) cases of neonates with CNMs that were encountered at our tertiary center. Additionally, to best elaborate a comprehensive, case-based approach to CNM management, we offer an up-to-date, diagnosis-to-treatment review of current literature.

METHODS

Case series and systematic literature review.

RESULTS

Twenty-eight (28) studies are included since January 2000 to October 2021, with a total of 41 cases. Most common diagnosis was teratoma (78%). Female-to-male ratio was 2.5:1. Twenty percent of cases presented prenatally with polyhydramnios or elevated alpha-fetoprotein. Postnatally, the presenting symptoms most frequently encountered were respiratory distress (78%), oral mass (52%), and feeding difficulties (29%). Seventy-five percent of affected newborns showed symptoms within the first 24 hours of life. Forty percent of cases had comorbidities, especially in the head and neck region.

CONCLUSIONS

Congenital nasopharyngeal masses can be detected antenatally, or symptomatically immediately after birth. Airway protection is a cornerstone in the management. Selecting the right imaging modality and convening a multidisciplinary team meeting are important toward the planning of next steps/therapeutic approach. Typically, a transnasal or transoral surgical approach will be deemed sufficient to address the problem, with a good overall prognosis.

Life-Threatening Mediastinal Teratoma of Infant Requiring Emergency Surgical Removal

Background  Teratoma is a tumor derived from fetal germ cells with aberrant differentiation.

Case Description  A 3-month-old infant with a mediastinal tumor was referred to our heart center. She presented with progressive dyspnea, cyanosis, and the need to be manually ventilated. The computed tomography scan displayed a huge tumor restricting the distal trachea including the bifurcation. An emergent operation was performed and the tumor was completely removed. Histological examination confirmed a mature teratoma.

Conclusion  In such life-threatening situation, the early detection and the immediate operation are very important for the management of rapidly-progressing mediastinal teratomas compressing the respiratory tract.

Somatic-type Malignancies in Testicular Germ Cell Tumors: A Clinicopathologic Study of 63 Cases

The development of somatic-type malignancies (SMs) in testicular germ cell tumors (GCTs) is a rare but well-recognized phenomenon. We studied the pathologic features of 63 GCTs with SMs in the testis (n=22) or metastases (n=41) and correlated these features with clinical outcomes. The patients with SMs in the testis (median age, 26 y) were younger than those with metastatic SMs (median age, 38.5 y). The SMs consisted of carcinomas (n=21), sarcomas (n=21), primitive neuroectodermal tumors (n=15), nephroblastomas (n=3), and mixed tumors (n=3). Sarcoma was the most common SM in the testis (n=11), and most sarcomas were rhabdomyosarcomas (n=9). Carcinoma was the most common SM in metastases (n=20), and most carcinomas were adenocarcinomas (n=12). In metastases, carcinomatous SMs developed after a longer interval from the initial orchiectomy (median times, 213 mo) than sarcomatous SMs (median times, 68 mo). Patients with metastatic SMs had significantly poorer overall survival than those with SMs in the testis (5-y survival rate, 35% vs. 87%; P=0.011). Furthermore, patients with carcinomatous SMs had a significantly worse prognosis than those with sarcomatous or primitive neuroectodermal tumor SMs (5-y survival rates, 17%, 77%, and 73%, respectively; P=0.002), when the whole cohort, including testicular and metastatic SMs, were analyzed. Our results demonstrate that SMs in metastatic GCTs are associated with a significantly worse prognosis than those in the testis. Furthermore, the histologic subtype of SM has a significant effect on the clinical outcome, with the carcinomatous SM carrying the highest risk for mortality.

Coexisting Cystic Lesions with Right-Sided Congenital Diaphragmatic Hernia in a Neonate

Diaphragmatic defects involving the right side of the diaphragm are less common but represent a distinct entity. The clinical presentation, management, and prognosis differ significantly from a left-sided defect. We report a case of a term neonate who was diagnosed to have a congenital diaphragmatic hernia during the third trimester of pregnancy, operated at 36 h of life and subsequently found to have an associated mediastinal cyst in 1^st week of life.

Melanosis tubae et ovarii: An overlooked entity?

Melanosis is a rare benign entity defined by the deposition of brownish-black pigment in a wide variety of organs especially the gastrointestinal tract, peritoneum, fallopian tubes and ovaries. Melanosis of the fallopian tube is widely known as pigmentosis tubae. Literature has mentioned ovarian teratomas and serous cystadenomas to be associated with the ovarian and peritoneal melanosis. We report five such cases of tubo-ovarian melanosis. The cases include mature teratoma and serous cystadenoma as well as melanosis of the fallopian tubes with otherwise normal ovarian histology. The importance of recognising this entity lies in its differential diagnosis.

Primary ovarian mucinous carcinoid arising in a mature cystic teratoma-A rare entity

Mature cystic teratomas are benign unilateral tumors often diagnosed in young females. Carcinoid tumors are slow-growing tumors originating from neuroendocrine cells. A thorough histopathological study of the tumor is mandatory and the surgical treatment is adapted according to the characteristics of the patient. The present case was considered as a primary mucinous carcinoid tumor of the ovary because it was confined to the ovary, had an intact capsule, no vascular invasion, or other suspicious lesions were noted in the abdominal cavity. This case is notable due to the rarity of its occurrence and the age of presentation.

Benign Renal Tumors in Pediatric Age Group: Retrospective Analysis

Background:

Benign renal tumors are extremely rare and were studied here. This series also includes a renal teratoma in a horseshoe kidney, probably only the second in the pediatric literature.

Materials and Methods:

Retrospective review of children with benign renal tumors operated between 2006 and 2018 at one center.

Results:

Twelve patients (M:F ratio 10:2), age range 3 weeks (31-week gestation) to 13 years presented with large palpable renal swelling (n = 12) and hematuria (n = 3). Computed tomography (CT) scan showed features typical of the tumor. Final histopathology (age group [mean]) showed: multilocular cystic nephroma (MLCN) - n = 5 (41.7%), (11–16 months [13.6]); congenital mesoblastic nephroma (CMN) - n = 4 (33.3%) (classic 1, cellular 3) (0.75–5 months [2.125]); mature cystic teratoma - n = 1 (8.3%): (48 months, in a horseshoe kidney), and angiomyolipoma (AML) - n = 2 (16.7%) (144 months [sporadic] and 156 months [tuberous sclerosis]) One patient with cystic teratoma with no calcification on CT scan received pre-operative chemotherapy as fine-needle aspiration cytology (FNAC) reported malignant small blue cell tumor. Nephroureterectomy with Gerota's fascia could be done easily in all without intraoperative complications. Delay in presentation in MLCN and CMN led to increased symptoms and CT scan changes. All patients did well in 1.5–12 years (median 3 years) follow-up including cellular mesoblastic nephroma.

Conclusions:

Benign renal tumors often occur in specific age groups but may overlap that of Wilms tumor. Proper interpretation of clinical presentation, CT scan, and FNAC findings help in avoiding preoperative chemotherapy. Upfront nephroureterectomy is curative. Histopathological findings decide further treatment. Children with AML and tuberous sclerosis need lifelong follow-up.

Non-histone methylation of SET7/9 and its biological functions

BACKGROUND

(su(var)-3-9,enhancer-of-zeste,trithorax) domain-containing protein 7/9 (SET7/9) is a member of the protein lysine methyltransferases (PLMTs or PKMTs) family. It contains a SET domain. Recent studies demonstrate that SET7/9 methylates both lysine 4 of histone 3 (H3-K4) and lysine(s) of non-histone proteins, including transcription factors, tumor suppressors, and membrane-associated receptors.

OBJECTIVE

This article mainly reviews the non-histone methylation effects of SET7/9 and its functions in tumorigenesis and development.

METHODS

PubMed was screened for this information.

RESULTS

SET7/9 plays a key regulatory role in various biological processes such as cell proliferation, transcription regulation, cell cycle, protein stability, cardiac morphogenesis, and development. In addition, SET7/9 is involved in the pathogenesis of hair loss, breast cancer progression, human carotid plaque atherosclerosis, chronic kidney disease, diabetes, obesity, ovarian cancer, prostate cancer, hepatocellular carcinoma, and pulmonary fibrosis.

CONCLUSION

SET7/9 is an important methyltransferase, which can catalyze the methylation of a variety of proteins. Its substrates are closely related to the occurrence and development of tumors.

Fetus-in-Fetu: A Case of Ovarian Involvement and Residual Regrowth in a Teenager

BACKGROUND

Fetus-in-fetu (FIF) is a rare, congenital soft tissue mass typically occurring retroperitoneally in neonates younger than 18 months. We present a 13-year-old girl with an ovarian FIF occurrence and subsequent residual regrowth after resection.

CASE

A 13-year-old girl presented with abdominal pain and was found to have a 19-cm, complex, right adnexal mass. Preoperative tumor markers were normal and risk assessment favored a benign process. She underwent open ovarian cystectomy with pathology showing FIF. Nine months later, she had a recurrence of her ovarian mass and underwent right oophorectomy, with FIF on pathology.

SUMMARY AND CONCLUSION

In patients in whom FIF is discovered within the ovary, consider postoperative surveillance, because of the risk of recurrence or residual disease.

Hyperthyroidism associated with struma ovarii - a case report and review of literature

BACKGROUND

Hyperthyroidism is a state characterized by elevated serum level of thyroid hormones: thyroxine (T4) and triiodothyronine (T3). This is mainly related to the condition and functioning of the thyroid gland. In 60-80% of cases elevation of these hormones are caused by Grave's disease. Thyrotoxicosis is an extreme presentation of hyperthyroidism which can, in rare cases, be caused by excessive synthesis of thyroxine by tumor cells. Struma ovarii is a rare ovarian teratoma composed of thyroid tissue in more than 50%.

OBJECTIVE AND METHOD

To present a case of a 30-year-old female patient with a past history of Grave's disease treated by strumectomy 7 years prior; now presenting for the assessment of secondary amenorrhea. Pelvic ultrasound revealed bilateral solid tumors on the left and right ovary, respectively measuring 5 cm and 6 cm in diameter. Her clinical presentation was suggestive of overt hyperthyroidism, and she presented with a significantly elevated CA-125 (152.7 U/mL).

RESULTS

The patient subsequently underwent a bilateral oophorectomy in which both masses were excised and histopathological examination confirmed teratoma maturum cysticum. Struma ovarii was noted as a component of the left ovary teratoma.

CONCLUSION

Establishing a proper diagnosis of hyperthyroidism and elucidating its origin is often challenging. Struma ovarii is a rare cause of hyperthyroidism but should always be considered in case of treatment resistant hyperthyroidism. This case-report lends itself as an example of the value in maintaining gynecological-endocrinological knowledge in the setting if clinical gynecology.

Malignant transformation of mature cystic teratoma into undifferentiated carcinoma: A case report

Malignant transformation of mature cystic teratoma (MCTO) is a rare entity. Even rarer is the transformation of MCTO into undifferentiated carcinoma. We report a case of an 80-year-old woman with undifferentiated carcinoma and squamous cell carcinoma component originating from mature cystic teratoma of the ovary.

Ovary-Sparing Surgery for Ovarian Teratoma in an Infant with Nonbilious Vomiting

Ovarian teratoma is the most common ovarian tumor in children with an overall incidence of 2.6 cases per 100,000 girls per year. Diagnosis and management are challenging due to its nonspecific presentation, malignancy determination, and need to conserve fertility. A previously healthy 5-month-old female infant presented with fever, abdominal distension, and nonbilious emesis, and an 8.2 × 6.8 × 6.1-centimeter pelvic mass originating from the left adnexa was found on imaging. Due to concern for malignancy and torsion, exploratory laparotomy and ovarian-sparing surgery (OSS) with resection of the mass were performed. Histology showed a grade 1 teratoma. This case illustrates a challenging diagnosis and its symptom overlap with other etiologies in infants. The keys to diagnosing and managing this entity are including ovarian pathology in the differential diagnosis and performing OSS whenever possible. Furthermore, ultrasound follow-up is needed to monitor for ipsilateral and contralateral ovarian tumors later in life.

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.