Atypical Choroid Plexus Papilloma in a Newborn, Misdiagnosed by Ultrasound and MRI: A Case Report.

BACKGROUND Choroid plexus tumors (CPTs) are rare brain tumors that originate from the choroid plexus epithelium and range from low-grade papillomas to overtly malignant carcinomas, and can occur in newborns. According to the World Health Organization's histological classification, atypical choroid plexus papilloma (aCPP) is an intermediate-grade (Grade II) lesion characterized by an increased mitotic rate. It is difficult to distinguish CPTs on imaging during the early stages. The present article aims to increase awareness and vigilance regarding CPTs. CASE REPORT A newborn girl was admitted to the hospital on the day of her birth with suspected intracranial hemorrhage, after visualization of a hyperechoic lesion in the right lateral ventricle the day before delivery. During hospitalization, her neurological examinations revealed no abnormalities. Cranial ultrasound showed that the right choroid plexus was thicker, with stronger echo and more Doppler flow than the left side. MRI revealed an isointense mass located in the right ventricular trigone. She was treated conservatively for suspected intraventricular hemorrhage, and 3 months later, her head circumference increased. A follow-up MRI showed that the lesion had greatly enlarged. Consequently, surgery was performed, and the histopathologic finding showed it was aCPP. CONCLUSIONS CPTs are rare tumors that do not have specific clinical patterns or imaging findings, and they can easily be misdiagnosed as intraventricular hemorrhage. The thickening of the choroid plexus, which presents with a highly echogenic appearance and enhanced blood flow signals, might be an ultrasound feature indicative of CPTs.