Diffuse midline glioma, H3K27-altered, of the conus medullaris presenting as acute urinary retention: illustrative case

Abstract

BACKGROUND Diffuse midline glioma (DMG), H3K27-altered, is a rare, highly malignant central nervous system neoplasm that arises in midline structures. They are more commonly encountered in children and are rarely encountered in adults, usually in the thalamus or spinal cord. The presence of the H3K27 mutation in the H3F3A gene automatically classifies a tumor as World Health Organization grade IV. These tumors carry a grim prognosis, with an overall median survival of less than 1 year. OBSERVATIONS The authors report the case of a 38-year-old male presenting with acute-onset urinary retention who was found to have an expansile, well-circumscribed mass involving the conus medullaris at the level of T12–L1. A T12–L1 laminectomy and tumor debulking were performed. Pathology revealed glial cells with astrocytic morphology among Rosenthal fibers, microvascular proliferation, and cellular atypia. The H3K27 mutation was confirmed. LESSONS DMG, H3K27-altered, is a rarely encountered entity that can present in numerous midline structures. If localized to the conus medullaris, it may present as acute-onset urinary retention in a previously asymptomatic patient. Further investigation is needed to characterize its molecular and clinical features in adults to improve the management of those presenting with these tumors.

Diffuse Midline Gliomas: Challenges and New Strategies in a Changing Clinical Landscape

“…Spinal DMGs share features with their cranial counterparts, with growth patterns logically restricted by the limited axial spread possible within the spinal cord; thus, these lesions have a predominant rostro-caudal elongation rather than anterior–posterior or medio-lateral one. They are characterized by a significant FLAIR signal often spanning multiple spinal levels and poorly differentiated contrast enhancement ( Figure 2 E,F) [ 28 , 29 ]. Spinal DMGs can be difficult to distinguish from other astrocytic spinal lesions; these tend to be more eccentric and can have stronger contrast enhancement, albeit the two entities can be difficult to separate by MRI alone [ 30 ].…”