Unique presentation of cerebellopontine angle choroid plexus papillomas: case report and review of the literature

Abstract

Objectives We present the case of a choroid plexus papilloma (CPP) in the cerebellopontine angle (CPA), describe the different appearances of CPPs with a variety of imaging techniques, and discuss the differential diagnosis of CPA tumors. Participant and Design We report the case of a 52-year-old woman with headache, tinnitus, and unilateral hearing impairment whose preoperative magnetic resonance imaging revealed a heterogeneously enhancing CPA mass that extended into the internal auditory canal. Main Outcome Measures, Results, and Conclusion The preoperative imaging appearance of the lesion was most consistent with that of a schwannoma. Postoperative histopathologic examination found the tumor to be a CPP with cuboidal epithelial cells overlying fibrovascular stroma. CPPs are rare benign central nervous system neoplasms arising from choroid plexus epithelium. The most common site of presentation is in the fourth ventricle in adults and the lateral ventricles in children. CPPs rarely occur in the CPA, and when they do, clinical-radiologic diagnosis is difficult due to both the rarity of this presentation and to nonspecific radiological features.

Keywords: cerebellopontine angle; choroid plexus papilloma.

Fig. 1

Preoperative magnetic resonance imaging (MRI). (A) Axial T2-weighted MR image displaying a well-circumscribed heterogeneous extra-axial mass centered in the right cerebellopontine angle (CPA). The lesion is causing marked mass effect on the right middle cerebellar peduncle (right brachium pontis) and the fourth ventricle resulting in mild hydrocephalus (not shown). (B) Axial T1-weighted MR image displaying the right CPA mass to be hypointense with respect to brain parenchyma. (C) Axial T1-weighted contrast-enhanced MR image displaying heterogeneous enhancement of the right CPA mass. In addition, there is evidence of contrast enhancement extending through the porous acusticus and along the posterior wall of the left internal auditory canal (arrow). (D) Coronal T1-weighted contrast-enhanced MR image identifying the extension of contrast into the internal auditory canal (arrow).

Fig. 2

Cerebral angiogram. An exaggerated transfacial view of a selective right vertebral artery injection did not show a clear area of enhancement in the right cerebellopontine angle. The caliber of the mildly displaced left anterior internal cerebellar artery (arrow) is smaller than the right side (star).

Fig. 3

Postoperative magnetic resonance (MR) imaging. (A) Axial T1-weighted contrast-enhanced MR image displaying no residual contrast enhancement. (B) Coronal T1-weighted contrast-enhanced MR image displaying no residual contrast enhancement.

Fig. 4

(A) Hematoxylin and eosin (H&E) stain (× 40) showing a hypercellular smear with a papillary fragment of tissue. (B) Romanowsky stain (× 200) showing a fibrovascular structure lined by bland, crowded, and pseudostratified epithelial cells. (C) H&E stain (×400) showing thin cytoplasmic processes coming off bland-appearing epithelial cells. (D) Frozen section H&E (×400) showing bland epithelial cells lining a fibrovascular core with distinct cytoplasmic borders. Neuropil elaboration is not identified.

Fig. 5

(A) Permanent section hematoxylin and eosin (H&E) (× 40) showing fibrovascular cores lined by bland epithelial cells. (B) Permanent section H&E (× 100) (higher magnification of Fig. 2A). (C) Permanent section H&E (×400) (higher magnification of Fig. 2B) showing crowded columnar cells with a high nuclear to cytoplasmic ratio. No atypia, necrosis, or significant mitotic activity is identified. (D) Transthyretin antibody (×200) highlighting the epithelial cells.