Extracranial medulloepithelioma: a review of the literature

Purpose: Medulloepithelioma is a rare, malignant tumor that typically arises in the periventricular region of the cerebral hemispheres or the ciliary body of the eye. Even rarer still is the extracranial manifestation of medulloepithelioma with only 12 cases reported to date. Our purpose is to report a case of an intradural, extra-medullary medulloepithelioma and review the limited literature about diagnosis and treatment of this extremely rare pathology.

Methods: PubMed was queried using search terms "peripheral medulloepithelioma" and "pre-sacral medulloepithelioma." Medulloepitheliomas which were intraocular or occurred in reproductive organs were excluded. Patients' age, sex, the symptomatic period prior to diagnosis, primary tumor site, stage, treatment regimen, pathologic description, and survival outcomes were collected.

Results: We present a case of extracranial medulloepithelioma in an 8-year-old male. Morphology of the neoplasm was representative of medulloepithelioma but there was no amplification of C19MC. Additionally, the neoplasm stained positive for CD99. Twelve other cases of extracranial medulloepithelioma were found in literature review.

Conclusions: The rarity of extracranial medulloepithelioma makes for a challenging diagnosis. Designing an optimal treatment strategy is difficult because of a scarcity of cases and wide variety in locations and treatments. Our case provides an example of treatment including resection, intense induction chemotherapy, consolidation with high-dose chemotherapy and stem cell rescue, craniospinal proton radiation therapy, and metronomic chemotherapy.