Diffuse Leptomeningeal Glioneuronal Tumours (DLGNT) is an extremely rare form of brain and spinal cancer which was characterized by the World Health Organization (WHO) in 2016. There are fewer than 100 cases of this largely paediatric cancer reported in literature and consequently, it remains poorly understood in children and adults alike.
Please see disclaimer at end of next section
Whilst DLGNT is largely described as a paediatric condition, there are a number of cases of teens/young adults, and even a few cases of older adults, diagnosed with this rare form of cancer.
Since its classification by the WHO in 2016, several types of DLGNT have been identified:
NTRK1/2/3 and TRIM33:RAF1 Fusions
Furthermore, in the literature DLGNT has been subdivided into two subgroups:
DLGNT methylation class (MC)-1
DLGNT methylation class (MC)-2
The latter generally signifies a more aggressive form of DLGNT and often displays a gain of chromosomal arm 1q and a 1p loss.
Initial Signs of DLGNT
DLGNT is difficult to diagnose and the disease is often confused with meningitis or migraine. Many cases start with clinical symptoms such as papilledema, nausea/vomiting, intense headaches/migraine and seizures, which are indicative of increased intracranial pressure.
Hydrocephalus is a common occurrence and ventriculoperitoneal (VP) shunt positioning remains a primary course of action for dealing with the excess cerebrospinal fluid (CSF) that collects in the brain's ventricles. In many cases the installation of a VP shunt occurs prior to diagnosis of DLGNT.
As with most cancers, early detection can lead to earlier diagnosis and understanding, along with potential treatment and likely superior outcomes. Diagnosis is possible through a combination of (a) judicious imaging including enhanced MRI scans and (b) surgical tissue biopsy and/or CSF liquid biopsy, both for diagnosis through molecular profiling, methylation or other means.
MRI Scans: Common findings from MRI scans (with contrast) include leptomeningeal thickening or nodularity in the brain and spine.
Surgical Tissue Biopsy: Due to the diffuse nature of DLGNT, tumours may not initially be found in the relatively small tissue samples from surgical biopsies of the brain or spine.
Liquid Biopsy: Liquid CSF biopsies offer a less invasive alternative especially if multiple biopsies are needed for diagnosis and further molecular profiling. It is important to note that although samples of CSF will often be taken for testing, early on in the disease progression most patients will have a negative CSF cytology.
Radiotherapy and proton-therapy seem to have some temporal effect on the tumours, but also have harsh secondary effects on the patients and it is not recommended by many paediatric oncologists as the first line of defense.
There are a number of targeted chemotherapy drugs which have been successful in reducing the tumours in the brain and spine in some DLGNT patients. Nevertheless, it is essential to understand the characterisation of each patient's tumours through molecular profiling prior to selecting a targeted treatment (for example, the chemotherapy drug used for treating BRAF V600E can accelerate the development of the tumours in a BRAF-KIAA1549 Fusion).
However, currently there is no standardized treatment protocol for DLGNT. So what can we do to help ?
Our goals are to:
Create awareness of DLGNT amongst oncologists, neurologists and pathologists to enable earlier diagnosis;
Build a community of DLGNT patients where information and experiences can be shared; and
Facilitate medical data sharing to enable further research into DLGNT so that oncologists globally can treat patients with DLGNT more effectively.
Please note that all of the above information is based on a combination of our own research and from conversations with oncologists, neurologists and pathologists in the UK, Germany, Italy, USA, Australia and Canada. This is not a medical opinion and anyone reading this will need to discuss the particulars of their condition with qualified medical professionals.
We simply aim to raise awareness of some of the issues that we experienced with diagnosing and treating DLGNT in the case of our son. We were fortunate enough to be able to talk to some of the leading paediatric/adult oncologists during our search for the right treatment of our son and we want to share information on DLGNT with other people who may be wondering, as we were, what they can do to help their child.