T spinal nerve roots on the transverse slices (Fig. 2). Neither bony
T spinal nerve roots on the transverse slices (Fig. 2). Neither bony Camptothecin nor surrounding soft tissueassociated abnormalities could be seen. Given the age of the dog, the location, the shape and the MRI features of the lesion, we hypothesized that this was a neoplastic process such as an extrarenal nephroblastoma or a cystic structure such as an epidermoid cyst. The dog underwent surgery under general anesthesia. A standard approach toFig. 3 Intra-operative view of the cyst after durotomyFerrand et al. Irish Veterinary Journal (2015) 68:Page 3 ofremoval was possible and appeared to be complete. A concave imprint of the lesion was still present. Summarily, the mass was left sided extramedullary and intradural without nerve root involvement. Pathological analysis showed a voluminous cystic lesion (approximated size of 10 mm ?6.5 mm) lined by a heterogeneous epithelium (Fig. 4). A pseudostratified columnar epithelium with cylindrical cells with basal nuclei and round-shaped apical poles, evoking an enteral or respiratory epithelium, was observed (Fig. 5a). Structures such as cilia or microvilli were sometimes present at the apical pole (Fig. 6). Moreover, a stratified squamous epithelium evoking a Malpighian epithelium, but without keratin production, was observed (Fig. 5b). Finally, a transitional epithelium similar to urinary epithelium was present. Mucus production was established by histochemical assays utilizing periodic acid-Schiff (Fig. 7a and b) and alcian blue (Fig. 7c). This highlighted the secretory nature of the epithelium. All of these different epithelia lacked differentiation. Immunohistochemical labelling was carried out. The wall of the cyst showed antigens of cytokeratin. This finding was consistent with the epithelial nature of the tissue. The cystic epithelial cells also stained positively for carcinoembryonic antigen (Fig. 8). This finding was consistent with an endodermal origin of the cyst. In contrast gliofibrillar acid protein and vimentine antigens were not expressed. Mucus production and the morphology of some cells with microvilli at the apical pole were also highly in favor of an endodermal origin of the cyst. The association of a cystic structure with heterogeneous epithelia of endodermal origin led to the diagnosis of aFig. 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)spinal neurenteric cyst, as described in humans. Postoperatively, neurological deficits dramatically worsened; the patient was paraplegic with loss of nociception in the left hind limb. Deep pain sensibility recovered after 5 days and the capacity to walk after 10 days. Fecal andFig. 4 Photomicrograph of the neurenteric cystFig. 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 cellsFerrand et al. Irish Veterinary Journal (2015) 68:Page 4 ofFig. 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 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/7500280 a basal nucleus and convex borders (b). Alcian blue staining is also positive, highlighti.
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