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Juliana Campos de Barros , Larissa Garbelini Valentim , Raira Costa Dias , Alfredo Hajime Tanaka Pereira , Giovana Wingeter Di Santis & Mônica Vicky Bahr Arias
ABSTRACT
Background: Spinal neoplasms are classified into extradural, intradural/extramedullary or intramedullary. Intradural/extramedullary
tumors include meningiomas and nerve sheath tumors, which arise from meninges or peripheral nerves around
the spinal cord. Clinical signs are related to dysfunction of the involved nerve and include pain, nerve root signature and
atrophy. Osteochondromas are benign tumors located within the bone, on its surface or in extra-osseous regions, when they
are classified as soft tissue osteochondoma. The aim of this study is to describe a case of an osteochondroma in a nervous
root of the cauda equina in a dog, whose surgical resection allowed the resolution of the clinical signs.
Case: A 12-year-old, male, Labrador Retriever dog, was presented with a 40-day history of progressive, painful, pelvic
limb paresis, with no improvement when treated with analgesics and acupuncture. Neurological abnormalities included
paraparesis, sometimes worse in the left pelvic limb, that was carried flexed at the level of the stifle, hindlimb atrophy,
decreased interdigital reflexes and pain in the lumbar spinal region, mainly over L6 vertebra. Results of blood count and
serum biochemical analysis were unremarkable. Computed tomography (CT) of the lumbosacral area was performed and
the evaluation of images in transverse and reconstructed dorsal and sagittal planes allowed the visualization of a hyperattenuating
and calcified round structure with 8 mm x 6 mm, in the left side of vertebral canal, at the level of caudal epiphysis
of L6. Lumbosacral (L7-S1) CT abnormalities, as subchondral sclerosis, mild disc margin bulging, spondylosis deformans
and foraminal proliferation were also observed but were considered clinically insignificant. Then, a dorsal L6 laminectomy
was performed and after opening of the vertebral canal it was observed the presence of an ovoid mass, in the left side of
the medullary cone, measuring approximately 0.9 cm in length, originating from a sacral nerve root. This structure was
excised and submitted to histopathological evaluation. The dog improved after surgery without any complications, and
neurological functions were gradually recovered. The histopathology of the mass was confirmed as an osteochondroma.
Discussion: The history and neurologic examination findings as well the improvement after surgery were compatible with
the lesion visualized by TC in L6, rather than the degenerative changes in L7-S1. Regarding the position of the mass, the
main differential would be nerve sheath tumor, one of the most common types of primary neoplasia of the peripheral nervous
system, however in a CT study in dogs with brachial plexus and nerve roots neoplasms, calcification of the tumor was not
observed. Most of benign cartilaginous tumors of soft tissue are chondromas/osteochondromas, and this lesion should not
be confused with multiple osteochondroma or multiple cartilaginous exostoses, which have been reported as multifocal,
proliferative lesions involving the surface of ribs, vertebrae and pelvis of young dogs. If this lesion is unique, it is called
osteochondroma. There are two reports of chondromas into the first lumbar vertebrae of dogs, with adherence to the floor
of the vertebral canal and one report of an osteochondroma originated from the left pedicle of T11 in a cat. Radiculopathy
and myelopathy caused by osteochondromas inside the spine are rare in humans and description of this tumor arising from
nerve roots were not found in the veterinary literature. Probably the origin of the mass was metaplasia of the meninges
surrounding the nervous root. In conclusion, neurological examination, CT and surgical exploration allowed the diagnosis
and removal of a soft tissue osteochondroma, a rare benign tumor, with good patient recovery
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