Adult hemispheric cerebellar medulloblastoma

Abstract

Background: Medulloblastoma is an embryonal neoplasm and accounts for 1% of all adult intracranial tumors. It is associated with many familiar cancer syndromes, but there is no known cause for medulloblastoma. Many studies have documented differences between childhood and adult medulloblastomas in terms of location, proliferation, and apoptotic indices. There are four histological groups - classic and the variant forms (desmoplastic/nodular, anaplasic, and large cell). There are four major subgroups according to molecular configuration: wingless (WNT), sonic hedgehog (SHH), group 3, and group 4 with differences between them according to prognostic outcomes.

Case description: We present the case of a 19-year-old female who complained of headache and vomiting. On neurological exam, she was awake, conscious, and had mild truncal ataxia, dysmetria, and intentional tremor. Brain magnetic resonance imaging (MRI) showed an intra-axial left hemisphere cerebellar lesion causing midline shift tonsilar herniation. She was submitted for posterior fossa craniotomy and microsurgical resection of cerebellar tumor and then to 18 Gy adjuvant radiotherapy to the tumor bed and 23 Gy to the neuroaxis.

Conclusion: This article briefly discusses the newest points in classification, diagnosis, and treatment of medulloblastoma. This case illustrates the diagnostic workup and treatment of a rare tumor in adults showing the importance of molecular and histological studies for the treatment and counseling of the patient. Medulloblastoma has different prognosis depending on the histological and molecular feature. Accessing these different features is essential to better plan the treatment as well as inform the patient regarding the disease and its prognosis.

Keywords: Brain tumor; medulloblastoma; molucular profile.

Figure 1

Axial contrast-enhanced T1 image showing the tumor's dimensions (right). Sagital contrast-enhanced T1 image showing the relation between the mass and the cerebellar tentorium (left)

Figure 2

Post- operative MRI showing complete ressection of the tumor

Figure 3

Micropcopy showing highly cellular neoplasm composed of large cells with hyperchromatic nuclei, scant cytoplasm, nuclear molding and moderate pleomorphism, consistent with undifferentiated medulloblastoma

Figure 4

Scheme represents sinalization cascade for genesis of MB. Mutations in the genes that code for SHH signaling pathway receptors or downstream inhibitors may lead to hyperstimulation of the pathway, resulting in accumulation of oncogenic transcription factor GLI 1/2, activation of N-Myc and cellular deregulated proliferation. Mutations in genes that codify β-Catenin, results in accumulation of cytosolic β-catenin, activation of C-Myc and oncogenesis