Multiple Occipital Bone Lytic Lesions Containing Ectopic Cerebellar Parenchyma Mimicking Neoplasia

BACKGROUND

Nonlethal neural tube defects are developmental malformations with complex pathogenesis usually manifested at birth or in childhood.

CASE DESCRIPTION

We report the case of a 61-year-old woman without significant previous clinical history presenting for neck pain and stiffness. An extensive workup detected multiple lytic lesions within the occipital bone and cervical vertebrae, suspicious for multiple myeloma or metastatic disease. Surgical resection of the occipital bone lesions revealed ectopic cerebellar tissue, some containing folia with mature cortical lamination, and no evidence of malignancy.

CONCLUSIONS

To our knowledge, this study describes the oldest individual presenting with ectopic cerebellar tissue and the only instance in which oncologic workup for malignancy was carried out prior to resection. It also proposes surgical resection as a diagnostic and curative approach for this complex basicranium and neural developmental defect, and discusses retinoic acid toxicity as a possible cause of its occurrence.

Intraventricular Ectopic Cerebellum

BACKGROUND

Cerebellar ectopy is a rare finding, with few cases previously reported. Intraventricular localized cerebellar ectopy was described in only 1 case within the fourth ventricle.

CASE DESCRIPTION

A 9-year-old girl suffered for 2 years from bilateral frontoparietal headaches, sometimes accompanied by vomiting and photophobia. Magnetic resonance imaging demonstrated an oval-shaped lesion within the left lateral ventricle, characterized by well-defined margins without a clear cleavage plane from the adjacent choroid plexus. The mass presented an intermediate signal on T1- and T2-weighted sequences, similar to gray matter, and reduced ADC values on ADC maps compared with white matter, with no enhancement after gadolinium-based contrast injection. After resection, macroscopic examination revealed an organoid structure with leptomeningeal lining and a clear-cut cortex and white matter components. Histology demonstrated normal cerebellum with a double-layered cortex and normal underlying white matter. The cerebellar ectopy was focally covered by bundles of capillary vascular structures covered by a monostratified ependymal cell lining, consistent with choroid plexus.

CONCLUSIONS

We describe, for the first time to our knowledge, the case of a child with ectopic cerebellar tissue harboring the supratentorial ventricular system. Plausible etiologic mechanism consists in the herniation of the cerebellar germinal tissue into the ventricular system through the ependyma, allowing cell migration to the supratentorial compartment, followed by maturation into the normal cerebellum.

Ectopic cerebellar tissue in the occipital bone: a case report

BACKGROUND

Ectopic cerebellar tissue located distantly from the normal cerebellum is very rare, and its pathophysiology remains to be elucidated.

CASE PRESENTATION

We report an extremely rare case of intraosseous ectopic cerebellum detected incidentally at suboccipital craniotomy in a 46-year-old Japanese woman with hemifacial spasm. She had a small bone defect in the occipital bone, which contained a tiny area of soft tissue surrounded by cerebrospinal fluid connecting to the normal subarachnoid space through a dural opening. Histopathology demonstrated cerebellar cortex tissue consisting of molecular and granular cell layers.

CONCLUSIONS

This is the first report of glioneuronal ectopia within the skull bone separated from normal brain tissue, and it is important to distinguish this entity from other osteolytic lesions.

Ectopic cerebellar tissue of the posterior cranial fossa: diffusion tensor tractography and MR spectroscopy findings

PURPOSE

Well-differentiated ectopic cerebellar tissue is extremely rare, with only 12 cases in the literature. Here, we describe a unique case of radiologically proven ectopic cerebellar tissue, using diffusion tensor tractography (DTT) and MR spectroscopy (MRS) findings, in a 6-day-old newborn.

CASE

A 6-day-old newborn who had previously a fetal MRI referred to our department with the suspicion of an arachnoid cyst of the posterior fossa. Including the central nervous system, all of his physical examination tests were normal. Postnatal transcranial ultrasound (US) imaging and brain MRI also revealed a large posterior fossa cyst and a solid mass nearby the cerebellar tissue. The tissue showed a small connection and isointense signal with the cerebellum. Upon DTT, both the cerebellum and nearby solid tissue represented the same FA values. Tractographic studies showed a connection with fibers extending along the left cerebellar hemisphere from this tissue. The single voxel MRS of this solid tissue also revealed high choline (Cho) and a smaller N-acetylaspartate (NAA) concentration similar to that of the normal newborn cerebellum.

CONCLUSION

Ectopic cerebellar tissue can be characterized by advanced neuroimaging tools, like DTT and MRS, which provide information about brain metabolite concentrations and the microstructural integrity. In this way, unnecessary surgery can be avoided in order to obtain a histopathological diagnosis.