Objective

To explore the clinical characteristics of Mollaret meningitis（MM）in children.

Methods

One child with MM （child 1）who visited Shanghai Children's Medical Center，Shanghai Jiaotong University on March 3，2022 was selected as the research subject.A retrospective analysis method was adopted to analyze the clinical data such as the medical history，admission physical examination，relevant examination results and diagnosis and treatment process of child 1.With"Mollaret meningitis"and "child"as key words both in Chinese and English，the relevant literature of MM children were searched from Wanfang Knowledge Service Platform，CNKI，VIP and Pub Med.The literature retrieval time was set from the establishment of each database to December 30，2024.The procedures followed in this study was complied with the requirements of the Helsinki DeclarationoftheWorldMedicalAssociation revised in 2013.

Results

①Child 1 is a 12 years and 11 months old boy.He was admitted to Shanghai Children's Medical Center，Shanghai Jiaotong University due to"intermittent fever for half a year and headache for more than 2 months".After admission，the child 1 was treated with comprehensive treatments including cefotaxime，meropenem，vancomycin，and acyclovir for anti-infection，mannitol and concentrated sodium for reducing intracranial pressure，methylprednisolone for anti-inflammation，and immunoglobulin G supportive therapy.The child's condition improved several times，and he had no complaints of discomfort during the period of temperature relief.However，after the improvement，he developed fever and headache for unknown reasons three times.The results of cranial MRI examination showed enhancement of the bilateral frontal，temporal，and parietal-occipital pia mater，and meningitis was considered first；the bilateral paraventricular vascular spaces were widened，and the cistern magna was slightly enlarged.During hospitalization，cerebrospinal fluid was collected by lumbar puncture for examination for a total of 9 times.Among them，the white blood cell count，cerebrospinal fluid pressure and protein were high during 3 attacks，while the rest cerebrospinal fluid indicators were basically normal.No pathogens were detected in four next-generation sequencing（NGS）of cerebrospinal fluid and one NGS of meningeal tissue.Further hematological examinations did not reveal autoimmune or infectious diseases.The whole exome gene sequencing analysis results of child 1 and his father showed no abnormalities.Combined with the child's examination results and the course of the disease，he was clinically diagnosed as MM.Therefore，all anti-infective drugs were discontinued and only low-dose prednisone（15 mg/d×7 d，reduced to 10 mg/d×14 d，and then reduced to 5 mg/d for continuous oral administration）and mycomfetil capsules（500 mg per dose，twice daily，for a total of 60 days）were taken orally.One month before discharge，the temperature of child 1 was stable and there were no complaints of discomfort.The child 1 was discharged on June 3，2022.After discharge，telephone follow-up was conducted until the end of May 2024，he discontinued prednisone and mycophenolate mofetil capsules for more than one year，and there were no complaints of discomfort.②Literature review results：A total of 12 related literature on pediatric MM were retrieved，involving 15 children with MM，including child 1，a total of 16 cases.Among them，5 were male and 11 were female.The age of 1 case was unknown，and the ages of the remaining 15 cases ranged from 2 years and 6 months to 18 years.All of 16 children presented with fever and headache.One case was positive for the pathogen of herpes simplex virus （HSV）-1，three cases were caused by spinal cysts，and remaining 12 cases had no clear cause.The white blood cell counts of cerebrospinal fluid in all of 16 children during the attack period increased，and 9 cases were significantly increased，and the cerebrospinal fluid protein significantly increased in 9 cases during the attack period.Only 6 cases had Mollaret cells detected in the cerebrospinal fluid during the attack period.Cerebrospinal fluid pressure was reported in 5 cases，among which the cerebrospinal fluid pressure was significantly elevated in 4 cases.Ten cases were misdiagnosed as purulent/viral meningitis before being diagnosed with MM and were treated with antibacterial and antiviral drugs.All of 16 cases had a history of multiple recurrent attacks.The treatment mainly focused on etiological and symptomatic treatment.After treatment，except for child 2 who had epileptic seizures，the prognosis of the remaining 15 children was good.

Conclusions

Pediatric MM is rare in clinical practice and is prone to misdiagnosis.Clinically，for those with more than 2 recurrent episodes of meningitis，abnormal white blood cell count，protein and pressure in cerebrospinal fluid during the attack period，and a short-term recovery after treatment，MM should be considered.Treatment of MM child is mainly symptomatic based on finding possible related causes.