Spinal neurenteric cyst in a dog

Abstract

A 2-year-old female crossbreed dog was presented with progressive ataxia and paraparesis. A T3-L3 spinal lesion was determined by neurological examination. Magnetic resonance imaging (MRI) revealed an ovoid-shaped, well-circumscribed mass affecting the spinal cord at the level of the T9 vertebra. A left hemilaminectomy and a durotomy at the level of T9 allowed discovery of an ovoid deformation of the meninges with a cystic appearance. En bloc removal was performed and appeared to be complete. Pathological analysis showed a voluminous cystic lesion lined by a heterogeneous epithelium. Three types of epithelium were present: a pseudostratified columnar epithelium, a stratified squamous epithelium and a transitional epithelium. Mucus production, the morphology of some cells with microvilli at the apical pole and immunohistochemical assays were highly in favor of an endodermal origin of the cyst. The age of the dog, anamnesis, MRI study and histological findings were consistent with an intradural neurenteric cyst as described in humans. Total surgical removal led to a progressive clinical improvement with no recurrence at 18 months. We report an unusual intradural extramedullary cyst, called a neurenteric cyst, in a 2-year-old female crossbreed dog. This type of cyst is well-known in humans but has never been described in dogs. We propose that neurenteric cysts should be included in the differential diagnoses for tumor-like or cystic intradural lesions in the young dog. Prognosis for this type of cyst seems to be good, as total surgical removal led to a progressive clinical improvement with no recurrence at 18 months.

Keywords: Cyst; Dog; MRI; Spine.

Fig. 1

Sagittal (a) and dorsal (b) T2-weighted MRI slices of the intradural lesion

Fig. 2

Transverse T2-weighted slice of the lesion involving the whole diameter of the spinal cord. No relation with the nerve roots was seen

Fig. 3

Intra-operative view of the cyst after durotomy

Fig. 4

Photomicrograph of the neurenteric cyst

Fig. 5

The cyst was lined by multiple epithelial structures: pseudostratified columnar epithelium with cylindrical cells with basal nuclei and round-shaped apical poles suggesting an enteral or respiratory epithelium (a). Stratified squamous epithelium suggesting a Malpighian epithelium but without keratin production (b)

Fig. 6

Photomicrograph showing cells with basal nucleus and filiform apical cytoplasmic extensions, which look like microvilli. Periodic acid-Schiff staining is positive which highlights the production of mucus by these cells

Fig. 7

Photomicrographs showing the secretory function of the epithelium. Periodic acid-Schiff staining is positive (a), and highlights acidophil granules in the cytoplasm of caliciform cells with a basal nucleus and convex borders (b). Alcian blue staining is also positive, highlighting production of acid mucin (c)

Fig. 8

Photomicrograph showing positive staining for carcinoembryonic antigen