Lumbosacral intraspinal extradural ganglion cyst in a cat

Abstract

Case summary: A 16-year-old neutered female domestic shorthair cat was referred for chronic history of reluctance to jump, stiffness of the tail and lower back pain. Mild pelvic limb ataxia, reduced perianal reflex and lumbosacral discomfort were present on neurological examination. On magnetic resonance imaging, a well-defined rounded structure of 3 mm in diameter was identified on the right dorsal aspect of the epidural space at L7-S1, causing displacement of the cauda equina. The lesion was hyperintense to spinal cord parenchyma on T2-weighted images and hypointense on T1-weighted images, consistent with a fluid-filled structure. A Lumbosacral dorsal laminectomy was performed. A clear fluid-containing structure was identified between the right L7 nerve root and the cauda equina. Following surgical excision, histopathology confirmed the cystic nature of the lesion and revealed thick disorganised sheaths of fibrocollagenous tissue and flattened mesenchymal cells lining the luminal part of the cyst wall. A diagnosis of intraspinal ganglion cyst was made. The cat recovered uneventfully. Seven months after surgery euthanasia was performed for unrelated reasons; no neurological deficits were present.

Relevance and novel information: This is the first reported case of intraspinal ganglion cyst in a cat. Intraspinal extradural cysts should be considered among other differential diagnoses for cats with lumbosacral myelopathy/radiculopathy.

Figure 1

T2-weighted (T2W) and T1-weighted (T1W) (a, c) parasagittal and (b, d) transverse magnetic resonance images of the lumbosacral spine at the level of the lumbosacral joint. There is a T2W hyperintense and T1W hypointense well-circumcribed rounded lesion (arrowhead) in the vertebral canal craniodorsal to the L7–S1 intervertebral disc (IVD) and lateralised on the right side. The cyst-like structure extends dorsally, compressing and displacing the cauda equina dorsally and to the left. The lumbosacral IVD shows a decreased signal intensity, and signs of degeneration with osteophytic reaction on the ventral edges of the vertebral bodies.

Figure 2

(a) Histological section of the ganglionic cyst, featuring bundles of variously thick fibrocollagenous tissue characterised by multiple clefts and resembling the wall of a cystic structure. Haematoxylin and eosin (×2.5). (b) Detail of the luminal portion of the cyst wall at higher magnification. Multiple layers of flattened mesenchymal cells intermingle with dense collagen fibres. Haematoxylin and eosin (×10)