Ectopic cerebellar tissue in the occipital bone: a case report

Neuroimaging Features of Ectopic Cerebellar Tissue: A Case Series Study of a Rare Entity

Ectopic cerebellar tissue is a rare entity likely secondary to multiple, interacting, developmental errors during embryogenesis. Multiple sites of ectopic cerebellar tissue have been reported, including extracranial locations; however, an intracranial location is most common. We report on the MR imaging findings of a multi-institutional series of 7 ectopic cerebellar tissue cases (2 males, 4 females, 1 fetal) ranging from 22 weeks 5 days' gestational age to 18 years of age. All cases of ectopic cerebellar tissue were diagnosed incidentally, while imaging was performed for other causes. Ectopic cerebellar tissue was infratentorial in 6/7 patients and supratentorial in 1/7 patients. All infratentorial ectopic cerebellar tissue was connected with the brain stem or cerebellum. MR imaging signal intensity was identical to the cerebellar gray and white matter signal intensity on all MR imaging sequences in all cases. Ectopic cerebellar tissue should be considered in the differential diagnoses of extra-axial masses with signal characteristics similar to those of the cerebellum. Surgical biopsy or resection is rarely necessary, and in most cases, MR imaging is diagnostic.

Ectopic Cerebellar Tissue in the Occipital Bone: A Case Report

Ectopic cerebellar tissue has only been described in isolated case reports, with only two reported cases in adult patients. We report the case of a 63-year-old woman with progressive, medically refractory headaches. A scan showed an intraosseous lesion of the midline occipital bone. Surgical resection of the soft tissue lesion was undertaken. Her headaches ceased postoperatively. Histopathological analysis revealed cerebellar cortical tissue with a surrounding meningothelial cell layer, characteristic of cerebellar ectopia. This is the second reported case of an intraosseous location of this lesion, and only the third case described in an adult patient. Our findings illustrate a rare cause of headaches and support the therapeutic roles of surgical treatment for this extremely rare condition.

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.