Intracranial colloid cyst in the cerebellopontine angle of a dog: A novel case report and surgical outcome.

Authors

Hyeji Jo, Kang-Hyo Park, Donghwi Shin

Published in

Open veterinary journal. Volume 16. Issue 4. Pages 2366-2372. Epub Apr 30, 2026.

Abstract

Colloid cysts are benign endodermal intracranial lesions that typically arise in the third ventricle of the human brain. Although uncommon, obstructing cerebrospinal fluid pathways may cause clinical signs. Although cases in atypical sites such as the cerebellum or pontomesencephalic region have occasionally been described, no reports exist of colloid cysts within the cerebellopontine angle (CPA) in either veterinary or human medicine.
A 5-year-old castrated male Pomeranian presented with ataxia and excessive salivation. The neurological examination was largely unremarkable apart from gait disturbance. Magnetic resonance imaging revealed a well-defined cystic mass in the CPA measuring 12.7 × 12.7 × 10.8 mm, exerting compressive effects on the cerebellum and medulla. The lesion displayed gravity-dependent signal layering and peripheral rim enhancement, indicating a benign encapsulated cyst. Based on the location and imaging features, the differentials included epidermoid or dermoid cysts. Surgical removal was performed via dorsal craniectomy and durotomy to alleviate compression and establish a definitive diagnosis. Histopathology revealed a fibrous-walled cyst lined by ciliated cuboidal to columnar epithelium with papillary projections and no evidence of keratin, adnexal elements, or neoplasia. The findings were consistent with the presence of a colloid cyst. The patient made a complete recovery and remained clinically asymptomatic and neurologically intact during the 10-month follow-up.
This case represents the first known instance of a colloid cyst occurring in the CPA of a dog. The imaging and histologic features closely mirrored those described in human cases. The report highlights the need to consider colloid cysts among the differential diagnoses for CPA masses in dogs and underscores the importance of histopathological confirmation in cystic brain lesions presenting in atypical locations.

PMID:
42375941
Bibliographic data and abstract were imported from PubMed on 30 Jun 2026.

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