Intramedullary spinal cryptococcoma lesion in a dog diagnosed by magnetic resonance imaging, cerebrospinal fluid cytology and real-time PCR assay

Authors: Walmsley DW, Shaw T, Teh H, Kudnig ST
Publication: Australian Veterinary Practitioner, Volume 50, Issue 1, pp 23-31, Mar 2020
Publisher: Australian Veterinary Association

Animal type: Dog
Subject Terms: Animal remedies/veterinary medicines, Clinical examination, Imaging, Nervous system/neurology
Article class: Clinical Report

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Abstract:

Objectives: To describe the physical examination, diagnostic imaging, cerebrospinal fluid (CSF) cytology, and real-time polymerase chain reaction (RT-PCR) findings of a dog with an intramedullary spinal cryptococcoma.

Case report: A 3-year-old, entire male, Rhodesian ridgeback presented to a referral hospital for evaluation of a 5-week history of pelvic limb incoordination. Physical examination revealed a moderate pelvic limb ataxia with long-wide strides, a short-strided choppy thoracic limb gait and resentment of dorsal extension of the neck. All limbs were hypertonic. Neuroanatomic localisation was consistent with a C1-C5 myelopathy. Magnetic resonance imaging (MRI) revealed a large intramedullary lesion extending for the entire length of the adjacent vertebral body of C3 (approximately 5.4 cm long) with the following characteristics: T2-weighted hyperintense, T1-weighted hypointense, mild contrast enhancement and meningeal enhancement. Cisternal cerebrospinal fluid (CSF) analysis showed a marked mixed, predominantly eosinophilic and neutrophilic pleocytosis, with several deeply basophilic circular but speculated structures, 7-10 μm in diameter, often surrounded by a clear and indistinctly outlined capsule. RT-PCR analysis of the cisternal CSF sample confirmed the presence of cryptococcal DNA with a cycle threshold (CT) value of 34.94. Based on advanced imaging and laboratory findings, the diagnosis was intramedullary spinal cryptococcoma. Euthanasia was performed with necropsy examination declined.

Conclusion: To the authors' knowledge, this is the first reported case of an intramedullary spinal cryptococcoma lesion in a dog, diagnosed by MRI, CSF cytology and RT-PCR assay, in Australia.

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