Diffuse Leptomeningeal Glioneuronal Tumor

A 13-year-old patient with history of extra-gonadal germ cell tumour 3 years prior that responded successfully to chemotherapy, was brought for imaging follow-up. He referred having occasional headache as well as pain and paresthesia in both legs.

Physical exam revealed decreased strength of both legs, as well as decreased reflexes.

MRI (Magnetic Resonance Imaging) evaluation of the brain showed lepto and pachymeningeal diffuse enhancement also involving the basal cisterns. There were two cystic formations at the posterior fossa that had marked capsular enhancement in postgadolinium imaging.

Spine MRI revealed nodular lepto and pachymeningeal thickening.

Diffuse leptomeningeal glioneuronal tumour is a rare and recently described neoplastic condition that was included in the 2016 WHO (World Health Organization) classification of brain tumours [1]. It mainly affects patients in the pediatric age, mostly between 4 and 9 years of age.  Most patients are 6 years old when the diagnosis is stablished. 

The rarity of the disease and the lack of specific symptoms, contribute to a late diagnosis. Symptoms described include seizures, headache, paresthesia and extremity pain. CSF (cerebrospinal fluid) evaluation shows high protein count with normal glucose and normal cell count [2], a feature that can be confused with meningeal tuberculosis.

On imaging, this entity manifests as diffuse intracranial nodular leptomeningeal thickening with enhancement, diffuse intraspinal nodular leptomeningeal thickening and enhancement, and intramedullary spinal cord mass. A very particular feature that can be present is cystic-like lesions believed to be dilated Virchow-Robin spaces, believed to be caused by perivascular dissemination. Leptomeningeal thickening can lead to acueduct obstruction, which in turn can cause hydrocephalus [3].

Radiation therapy and standard chemotherapeutic regimens for low-grade gliomas can are recommended since it can slow down progression or even stabilize the disease if started early [4]; however, no standard management has been established.

The course of the disease is rather indolent due to the low proliferation rate; however delayed diagnosis can cause death in up to 63% of patients die within 9 months after diagnosis has been established [5].

Conclusion

Diffuse leptomeningeal glioneuronal tumour is a rare neoplastic entity that can be fatal if not diagnosed early. Radiologists from areas of high prevalence of tuberculosis must be very aware of the imaging features of it, since it is often misdiagnosed as meningeal tuberculosis; and those seeing follow-up studies of patients with CNS (Central Nervous System) tumours need to be aware of the possibility of this disease to not misdiagnose it as meningeal metastases.

Written informed consent from the patient’s parents for publication has been obtained.