Empiema epidural espinhal em gato com suspeita de linfoma em canal vertebral / Spinal epidural empyema in a cat with suspect of spinal canal lymphoma

ABSTRACT

Background: Spinal epidural empyema (SEE) is a rare disease in cats that has been described as a cause of severe compressive myelopathy. It is characterized by accumulation of purulent exudate in the form of an abscess in the epidural space. Neurological signs range from spinal hyperesthesia to rapidly progressive paraplegia and may be associated with systemic signs. Spinal lymphoma is the most common neoplasm affecting the central nervous system of cats and can mimic different neoplasms and non-neoplastic diseases, such as SEE. The aim of this study is to report a case of SEE in a cat and highlight the similarities in neurological, laboratory, and imaging findings between this disease and spinal lymphoma. Case A 8-month-old male neutered mixed-breed cat was referred to the Veterinary Medical Teaching Hospital (HVU) of the UFSM with acute, non-progressive paraplegia. On neurological examination, the patient was paraplegic with no nociception, normal spinal reflexes, increased muscle tone in the pelvic limbs, absence of cutaneous trunci reflex, and spinal hyperesthesia between T13-L1, demonstrating injury in the T3-L3 spinal cord segment. The differential diagnoses included acute spinal cord trauma, neoplasm (lymphoma), and infectious diseases. Hemogram showed lymphocytosis (8062/µL); the biochemical examinations were unremarkable. Tests for antibodies against feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) antigens were negative. Simple radiography, abdominal ultrasonography, and cerebrospinal fluid findings were also normal. Myelography showed left dorsolateral extradural spinal cord compression from T12 to L1. Based on these findings, the presumptive diagnosis was spinal lymphoma and chemotherapy was initiated. After 2 days, the animal began to show hyporexia, adipsia, vomiting, and diarrhea, in addition to an increase in subcutaneous volume in the thoracolumbar region. Antibiotic therapy was initiated; however, the patient died. Necropsy revealed an abscess in the left dorsolateral extradural space at T12-T13 and T13-L1. Bacterial cultures revealed the presence of Neisseria spp. that was resistant to various antibiotics. On the basis of these findings, the animal was diagnosed with SEE. Discussion: This case report aims to inform veterinarians about the diagnosis of SEE. SEE is a rare condition in cats compared to spinal lymphoma; however, their presentation is similar. Even in imaging examinations, such as magnetic resonance imaging, it is not possible to differentiate between these 2 conditions. The evolution of clinical signs made the diagnosis of the present case difficult since it was acute and not progressive. All cases of SEE reported in the literature were progressive, acute, or chronic. Although testing for FeLV was negative, only 56% of cats with spinal lymphoma test positive for this virus. Clinical signs reported by the owner after the start of chemotherapy may be related to adverse effects, such as immunosuppression, which led to worsening of the condition, culminating in the appearance of a subcutaneous abscess. Subsequently, SEE was suspected; however, surgical decompression was not performed as the animal died soon after. The authors of this report reinforce the need for a definitive and non-presumptive diagnosis of spinal lymphoma to initiate chemotherapy because it mimics different neoplasms and non-neoplastic diseases, such as SEE. Surgical removal of the compressive mass in the spinal cord and histopathological analyses are necessary.