Choroid plexus papilloma metastases to both cerebellopontine angles mimicking neurofibromatosis type 2

Abstract

Choroid plexus papilloma (CPP) is a benign tumor of neuroectodermal origin that occurs most commonly in the posterior fossa of adults [5]. Complete resection of the tumor typically results in a cure, but intracranial and spinal drop metastases occur [5, 8]. We present a patient with intracranial metastases from CPP involving both cerebellopontine angles (CPAs) and mimicking neurofibromatosis type 2 (NF2) [4]. When a 35 year old patient complained of headaches and episodes of blurred vision, an MRI scan was performed and revealed a well-circumscribed, contrast-enhancing, midline lesion in the fourth ventricle with no hydrocephalus. Suboccipital craniectomy resulted in macroscopically total excision of a well-circumscribed CPP. Sixteen years later, he developed transient visual obscurations in both eyes. Visual acuity was modestly reduced, left more than right, with a 2? afferent pupillary defect on the left and moderate atrophic papilledema bilaterally. Hearing was decreased on the left; he had no cafe au lait spots or other skin lesions. MRI revealed multiple enhancing extra-axial masses involving both CPAs, the foramina of Luschka and Magendie, the subfrontal region, and the middle and posterior cranial fossae (Fig. 1a, b, c). Masses had intermediate signal intensity on T1and T2-weighted images and multiple foci of punctuate calcification on CT. CPA masses extended into the internal auditory meatus, and the subfrontal mass measured 4 9 4.4 9 3 cm. Recurrence of CPP was considered, but NF2 was suspected both clinically and radiologically because of masses in both CPAs. Gross total resection of the large, symptomatic subfrontal mass was accomplished with no sequelae, and morphological and immunohistochemical features of the tumor were consistent with CPP (WHO grade I; Fig. 1d). The full coding region, exon–intron boundaries, and promoter region of the NF2 (neurofibromin 2) gene (NG_009057) were sequenced and no mutations were found. Benign CPP typically forms a well-defined, homogeneously enhancing mass on CT or MRI, occasionally in one or both CPAs at presentation [9]. Complete resection usually results in a cure, although recurrence and metastasis have been reported [5, 8]. Masses are usually isointense on T1-weighted images, showing a slightly high T2 signal intensity, and calcification is present in 4–20% of tumors. Various mechanisms have been hypothesized for dissemination, including iatrogenic seeding and local extension [4]. NF2 is a dominantly inherited, tumor-prone disorder characterized by the development of multiple schwannomas and meningiomas [1, 4]. The presence of bilateral vestibular schwannomas is considered pathognomonic [1]; however, bilateral CPA masses are not synonymous with bilateral vestibular schwannomas. Two previous reports describe patients with CPP metastatic to both CPAs [2, 3], leading to a challenging A. A. Al-Abdullah K. K. Abu-Amero (&) A. Hellani T. M. Bosley Department of Ophthalmology, College of Medicine, King Saud University, PO Box 245, Riyadh 11411, Saudi Arabia e-mail: abuamero@gmail.com