Primary leptomeningeal medulloblastoma

Primary Leptomeningeal Medulloblastoma in Adults: A Diagnostic Challenge-Case Report and Systematic Review

Primary leptomeningeal medulloblastoma (PL-MB) in adults is a rare disease with a severe prognosis. A 35-year-old woman presented with headaches, diplopia, and gait ataxia, with triventricular hydrocephalus and descent of the cerebellar tonsils beyond the foramen magnum. Endoscopic third ventriculostomy was performed. Six months later, headaches recurred. Dilatation of the supratentorial ventricular system and massive cerebellar swelling without contrast-enhancing nodularities were reported. Occipitocervical decompression with duraplasty was performed. A bioptic diagnosis of PL-MB was made. Craniospinal irradiation and chemotherapy were administered. After 18 months, no recurrence was observed. Few cases of PL-MB have been reported: patients die before treatment or within a few days after surgery. Our long-term survival could be ascribable to a slow clinical presentation and an early diagnosis that allowed surgical treatment and the administration of a combined chemoradiotherapy protocol. Cerebellar swelling, even without associated enhancing lesions, with or without hydrocephalus, should be a neuroradiological alarm sign, and PL-MB should be considered.

Medulloblastoma Presenting As Isolated Leptomeningeal Enhancement With No Primary Mass

Medulloblastoma presenting with diffuse leptomeningeal enhancement and no identified intra-parenchymal primary mass is extremely rare. A 14-year-old previously healthy boy presented with a three-week history of symptoms consistent with increased intracranial pressure (ICP). Magnetic resonance imaging (MRI) revealed diffuse leptomeningeal enhancement which prompted consideration of infectious, inflammatory, and neoplastic etiologies. The patient became rapidly unstable requiring the placement of an external ventricular drain (EVD) and induction of a phenobarbital coma for refractory seizures. The “sugar-coated” appearance of the abnormal enhancement and thickened tissues raised concern specifically for malignancy. The patient remained extremely unstable and ultimately required surgical decompression for increased ICP at which time a biopsy was obtained. Despite attempting bridging intra-ventricular chemotherapy, the patient, unfortunately, passed away, just 14 days from the initial presentation. Final pathology later confirmed the diagnosis of medulloblastoma. Awareness of medulloblastoma in the differential of diffuse leptomeningeal enhancement is crucial for early identification and treatment of this rare presentation. This case is the first pediatric report of primary leptomeningeal medulloblastoma without a primary mass involving the large cell/anaplastic variant.

Primary leptomeningeal medulloblastoma: a case-based review

BACKGROUND

Medulloblastoma (MB) is the most common malignant pediatric brain tumor, accounting for 40% of childhood tumors in posterior fossa. Metastatic disease, occurring in 20-30% of all medulloblastoma cases at diagnosis, is largely exclusive to the leptomeninges. On the contrary, primary leptomeningeal medulloblastoma or so-called chameleon medulloblastoma, defined by the absence of a detectable intraparenchymal lesion with a widespread diffusion along leptomeninges, is a rare entity of difficult diagnosis with only a few cases reported in literature.

METHODS AND RESULTS

A comprehensive literature search of three databases (PubMed, Ovid Medline, and Ovid Embase) have been conducted to identify pertinent papers focusing on the diagnostic process, management, and treatment of primary leptomeningeal medulloblastoma and its peculiar features. To our knowledge, only eight cases are described in literature, including five pediatric patients and three adults, two of which with the initial involvement of the spinal cord. In addition, we report another two pediatric cases, showing widespread primary diffusion along leptomeninges of brain and spinal cord. Finally, we analyze in-depth the peculiar morphological MRI features of this tumor.

CONCLUSION

The classification and treatment of medulloblastomas are likely to change in the coming years due to new insights into the molecular biology of medulloblastoma. Primary leptomeningeal medulloblastoma could represent another potential challenge for biologists to start exploring the underlying mechanisms of this different clinical and pathological entity, with different implications for diagnosis and its management.

Case Report: Primary Leptomeningeal Medulloblastoma in a Child: Clinical Case Report and Literature Review

Medulloblastoma is one of the most common pediatric central nervous system malignancies worldwide, and it is characterized by frequent leptomeningeal metastasizing. We report a rare case of primary leptomeningeal medulloblastoma of an 11-year-old Caucasian girl with a long-term disease history, non-specific clinical course, and challenges in the diagnosis verification. To date, 4 cases of pediatric primary leptomeningeal medulloblastoma are reported, and all of them are associated with unfavorable outcomes. The approaches of neuroimaging and diagnosis verification are analyzed in the article to provide opportunities for effective diagnosis of this disease in clinical practice. The reported clinical case of the primary leptomeningeal medulloblastoma is characterized by MR images with non-specific changes in the brain and spinal cord and by 18FDG-PET/CT images with diffuse heterogeneous hyperfixation of the radiopharmaceutical along the whole spinal cord. The immunohistochemistry and next-generation sequencing analyses of tumor samples were performed for comprehensive characterization of the reported clinical case.

Adult Spinal Primary Leptomeningeal Medulloblastoma Presenting as Pseudotumour Cerebri Syndrome

A previously well 34-year-old man presented with severe pseudotumour cerebri. Imaging showed that he had a cauda equina tumour which proved to be a medulloblastoma. There was no tumour mass in the posterior fossa so we assume that this was a primary leptomeningeal medulloblastoma. In patients with somewhat atypical pseudotumour, spinal imaging should always be considered.

A 22-year-old man with intracraneal hypertension and impaired sensation over the perineum and left foot

Primary leptomeningeal tumors are rare and can have multiple origins. This young man presented an intracranial hypertension syndrome and brain MRI features of diffuse leptomeningeal enhancement over cerebral and cerebellar hemispheres. A second cerebellar biopsy allowed the diagnosis of a primary diffuse leptomeningeal Primitive Neuroectodermal Tumor (PNET). Besides the paucity of reports of primary leptomeningeal PNET, its differentiation from primary leptomeningeal medulloblastomas is not always clear-cut and is discussed.