A rare case of adult diffuse midline glioma with H3 K27M mutant in the prepontine cistern

Abstract

Diffuse midline glioma with the H3.3 histone A (H3F3A) or H3 clustered histone 2/3 (HIST1H3B/C) K27M mutation occurs primarily in children and less frequently in adults involving the midline structures of the central nervous system. This case report describes an adult patient with a diffuse midline glioma H3 K27M mutant in the prepontine cistern, which is an unusual site in clinical practice. The clinical, radiographic and histopathological data from the case are presented. Magnetic resonance imaging showed a progressively enlarged and enhanced nodule in the right prepontine cistern, with diffuse involvement of the meninges and communicating hydrocephalus. Analysis of the cerebrospinal fluid occasionally found suspiciously atypical cells with hyperchromatic nuclei and multiple nucleoli, as well as a severely elevated opening pressure and protein level, slightly elevated white cell count and decreased chloride level. Empirical antituberculosis treatment was administered but eventually proved to be ineffective. The definite diagnosis was made by histopathological analysis of the lesion based on the features of positive H3 K27M mutant protein and diffusely infiltrating growth. A diffuse midline glioma with the H3 K27M mutation may rarely present in an unusual site. A biopsy is recommended at an early stage for suspected cases to facilitate a definite diagnosis.

Keywords: Diffuse midline glioma; H3 K27M mutant; adult; prepontine cistern.

Figure 1.

Initial magnetic resonance images of the brain of a 20-year-old female patient that presented with a 3-month history of daily persistent headaches that deteriorated at night. T1- and T2-weighted magnetic resonance images showed an iso-intense nodular lesion (arrow) in the right prepontine cistern (a, b). The lesion (arrow), as well as the adjacent basilar meninges, was obviously enhanced by gadolinium (c, d).

Figure 2.

Follow-up magnetic resonance images of the brain and spinal cord of a 20-year-old female patient that presented with a 3-month history of daily persistent headaches that deteriorated at night. The original nodular lesion (arrow) in the right prepontine cistern was enlarged with similar radiological features compared with the initial images (a). Sagittal T2-weighted imaging revealed slightly blurry plaques without gadolinium enhancement (arrow) in the cervical cord (b, c). Diffuse gadolinium enhancement (arrow) in the spinal meninges of the cervical, thoracic and lumbar cord was found (c, d).

Figure 3.

Histological and immunohistochemical examination of a biopsy specimen of the nodular lesion on the third lumbar segment showed infiltrating and nodular proliferation of pleomorphic cells with hyperchromatic nuclei and scant cytoplasm, which were dispersed in the hyperplastic fibrous tissue of the spinal meninges (A). These cells were strongly positive for the histone H3 K27M mutant protein (B), supporting a diagnosis of diffuse midline glioma H3 K27M mutant. Scale bar 20 µm. The colour version of this figure is available at: http://imr.sagepub.com.