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CASE REPORT

Immature ovarian teratoma with anti-NMDA-receptor
encephalitis in a 13-year-old Japanese female patient
George Imataka, MD, Shigemi Yoshihara, MD
Department of Paediatrics, Dokkyo Medical University, Tochigi, JapanSUMMARY
We report a 13-year-old Japanese female with ovarian
teratoma due to anti-NMDAR encephalitis. The patient wasadmitted with psychiatric symptoms, including memory
impairment, insomnia, binge eating and mouth and hand
twisting, associated with constipation. Serum alphafetoprotein and neopterin levels were elevated 102 ng/mL
and 19 pmol/mL, respectively. Electroencephalography
showed epileptic spikes in frontal and temporal regions.
Cerebrospinal fluid (CSF) examination exhibited apleocytosis. Thereafter, her consciousness level
immediately worsened. Brain magnetic resonance imaging(MRI) noted hyper intense lesions in bilateral hippocampi,
she was diagnosed with limbic encephalitis. Abdominal
echogram showed a solid right ovarian tumour. and also
confirmed as a tumour by abdominal MRI. The next day, rightovariectomy was performed and she treated two courses ofmethyl-prednisolone steroid pulse with high-dose
immunoglobulins. Later days, CSF analysis revealed antiNMDAR antibodies. Pathological diagnosis of the tumour
was immature round shaped grade 3 ovarian teratoma,measuring 11cm. Two years follow up after admission, shecompletely recovered and no neurological sequelae.

INTRODUCTION
Anti-N-methyl-D-Aspartate receptor (NMDAR) encephalitis israre form of autoimmunological encephalitis. In addition,
abdominal ovarian tumour complications have beenreported. We read with interest the report by Mahendra et al.1of a 16-year-old female with ovarian teratoma associatedwith anti-N-methyl-D-Aspartate receptor (NMDAR)
encephalitis diagnosed with rectal sonography andhistological examination of the cystic mass. We also treateda similar case of a 13-year-old Japanese female patient withovarian teratoma associated with anti-NMDAR encephalitis.
CASE REPORT
Two weeks after a bout of common cold, the above patient
was hospitalized with psychiatric symptoms, including
memory impairment, insomnia, binge eating and twisting ofmouth and hand, and accompanied with constipation.
Differential diagnosis included schizophrenia, epilepsy,depression and encephalitis. Blood and urine tests werenormal. She was negative for antinuclear, anti-doublestranded DNA and anti SS-A antibodies. Alpha-fetoprotein
and neopterin levels were 102 ng/mL and 19 pmol/mL,

Fig. 1: (A) Magnetic resonance fluid-attenuated inversion-recovery image at admission showing hyper intense lesions in bilateralhippocampi. (B) Abdominal magnetic resonance image showing a round tumour, 11 cm in size, with a non-uniform signal. (C)The maximum diameter of the mass is 12.0 cm.
This article was accepted: 28 March 2021
Corresponding Author: George Imataka
Email: geo@dokkyomed.ac.jp
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Case Reportrespectively. Brain computed tomography findings werenormal. Electroencephalography revealed sporadic spikes infrontal and temporal regions. Cerebrospinal fluid (CSF)
analysis revealed a pleocytosis. The tentative diagnosis wasviral encephalitis, and acyclovir and cefotaxime wereinitiated. However, her consciousness worsened immediately
and her brain magnetic resonance imaging (MRI) revealed
hyper intense lesions in bilateral hippocampi (Fig. 1A). She
was diagnosed with limbic encephalitis, and abdominal
ultrasonography revealed a solid right ovarian mass, which
was diagnosed as a tumour by abdominal MRI (Fig. 1B). The
updated diagnosis was anti-NMDA encephalitis due to an
ovarian tumour, and right ovariectomy was performed thenext day (Fig. 1C). After the operation, she received twocourses of methyl-prednisolone steroid pulse (30 mg/kg,3days) and high-dose immunoglobulins (400 mg/kg/5 days).
One week after operation, she was apathetic during the dayand apnoeic at night and had lost >10% body weight. She
was administered valproic acid for repeated generalized
seizures. Moreover, serum and CSF examination at admission
revealed the presence of anti-NMDAR antibodies. She
received another course of steroid pulse therapy, withsubsequent, gradual improvements in mental state andmemory. She was discharged two months after initialadmission. The pathological diagnosis of the right ovariantumour was immature grade 3 teratoma. Her IQ was 97 on
evaluation two years after surgery, and antiepileptic drug
treatment was discontinued at that time.

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DISCUSSION
In a study of limbic encephalitis by Dalmau et al.,2 91 of the
100 patients were females; young female patients werepredominant and 62% of the female patients had tumours,
most of which were ovarian teratomas. Early tumour removal
and immunotherapy are important for favourable outcomesin limbic encephalitis.3 A microscopic teratoma was detectedon autopsy in a case report. Therefore, exploratory
laparotomy should be considered in severe refractory cases.4
The prognosis was good following tumour excision in ourcase, similar to that reported by Mahendra et al.1 Sudden
appearance of psychiatric symptoms in young female
patients should warrant prompt brain MRI and abdominal
examination for potential ovarian teratoma associated with
anti-NMDA-receptor encephalitis.
REFERENCES

1. Mahendra INB, Saspriyana KY, Ekawati NP. Mature ovarian
teratoma associated with anti-N-Methyl-D-aspartate receptor
encephalitis: A case report. Med J Malaysia. 2021 Jan;76(1):110113.
2. Dalmau J, Gleichman AJ, Hughes EG, Rossi JE, Peng X, Lai M, etal: Anti-NMDA-receptor encephalitis: case series and analysis of
the effects of antibodies. Lancet Neurol 2008; 7(12): 1091-8.
3. Dai Y, Zhang J, Ren H, Zhou X, Chen J, Cui L, et al.. Surgicaloutcomes in patients with anti-N-methyl D-aspartate receptor
encephalitis with ovarian teratoma. Am J Obstet Gynecol 2019;
221(5): 485.e1-10.
4. Iizuka T, Sakai F, Mochizuki H. Update on anti-NMDA receptor
encephalitis. Brain Nerve 2010; 62(4): 331-8.

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