Objective:

To describe an atypical presentation of a rare adult-onset diffuse leptomeningeal glioneuronal tumor (DLGNT).

Background:

DLGNT is a rare glioneuronal neoplasm often described in children and adolescents with typically low-grade histological features. Adult-onset cases are rarely reported, and optimal management strategies remain undefined. Thus, we describe a case of DLGNT presenting later in life with reportedly chronic symptoms, but with distinctive cerebrospinal, radiographic, histological and molecular features.

Design/Methods:

NA

Results:

A 31-year-old man presented with a two-year history of progressively worsening, intractable bitemporal headache associated with nausea and vomiting, weight loss, and recurrent brief episodes of loss of consciousness. Initially diagnosed with migraines and undergoing seizure evaluation, the patient presented after subacute worsening of his symptoms. Examination revealed bilateral papilledema, diffuse hyperreflexia, and positive Hoffmann and Babinski signs bilaterally without weakness. Head CT demonstrated moderate ventriculomegaly consistent with communicating hydrocephalus.  A lumbar puncture revealed xanthochromia, markedly elevated protein, and low cellularity, consistent with Froin Syndrome. MRI Brain showed diffuse leptomeningeal enhancement (DLE) involving both supratentorial and infratentorial regions, without discrete mass lesion. MRI Spine demonstrated an intramedullary mass at T6–7 with DLE throughout the spinal canal. Surgical resection identified a WHO grade 2 DLGNT harboring a BRAF-KIAA1549 fusion and 1p/19q codeletion, negative for IDH1/2 mutations. Further analysis demonstrated 1q gain and a BCOR frameshift mutation. DNA methylation profiling classified the tumor as DLGNT-MC2. The patient underwent ventriculoperitoneal shunt placement and was started on trametinib with planned craniospinal irradiation. 

Conclusions:

This case highlights a rare case of DLGNT with unique adult-onset presentation with Froin syndrome. Thus, DLGNT should be considered for patients with such presentation with diffuse leptomeningeal enhancement and communicating hydrocephalus, despite age of onset. Additionally, comprehensive molecular characterization, including DNA methylation profiling, is essential for diagnostic accuracy and prognostication and contributes valuable data to the growing literature on this uncommon entity.