Clinical resolution of systemic mycobacterial infection in a cat with a suspected spinal granuloma

Abstract

An 8‐year‐old, female, spayed, domestic longhair cat presented with progressive pelvic limb weakness, lethargy and weight loss. Physical examination identified bilateral pelvic limb proprioceptive ataxia, tachypnoea and a subcutaneous nodular lesion on the left flank. Investigations documented a diffuse broncho‐interstitial and nodular pulmonary pattern, pyogranulomatous inflammation in the spleen and an intradural‐extramedullary spinal lesion at the level of L3. Mycobacterium microti was confirmed based on demonstration of organisms on histopathology of the subcutaneous nodule using Ziehl–Neelsen stain together with positive polymerase chain reaction and interferon‐gamma release assay results. Therapy with rifampicin, azithromycin and pradofloxacin was administered for 7 months. Serial monitoring, including repeated magnetic resonance imaging, demonstrated resolution of the clinical signs, pulmonary, subcutaneous and spinal lesions.

Toxoplasma gondii spinal granuloma in a cat

“…Note the cystic formation with granular content in the middle, being identified as bradyzoites (arrow) Extradural spinal granulomas have not been reported due to T gondii, but due to a variety of other infectious organisms, such as Cryptococcoma, Coccidioides immitis, Histoplasma capsulatum and Mycobacterium microti. 27,[30][31][32][33][34] To determine the aetiology of the extradural soft-tissue mass in this cat, a decompressive hemilaminectomy and tissue sampling were performed. Although the mass occupied approximately two-thirds of the vertebral canal, the cat showed only mild neurological signs, similar to some of the already reported extradural spinal granulomas due to parasite disease.…”