Rare Feline Case Reveals New Neurological Threat from Mycobacteria

Frontiers in Veterinary Science 2025

Case Report: Mycobacterial Epidural Pyogranulomatous Steatitis in a Cat

Flora Decrop, Tiago Henriques, Annika Hermann, Caroline Fina, Patricia Álvarez, Juanjo Mínguez, Christoforos Posporis

Background
Mycobacterial infections in cats are diverse, affecting various organ systems, but neurological involvement is rare. This case report describes a novel presentation of focal mycobacterial epidural pyogranulomatous steatitis in a young cat, adding to the sparse literature on feline spinal mycobacteriosis. The report aims to increase awareness of this pathogen as a differential in feline spinal pathology.

Methods
A 2-year-old neutered male domestic shorthair cat presented with chronic spinal hyperesthesia and acute tetraparesis. Diagnostics included physical and neurological exams, MRI, CSF analysis, serological tests, and surgical biopsy via hemilaminectomy. Histopathological analysis and hsp65 gene-targeted PCR were used to confirm the diagnosis. The cat was treated surgically and with a multi-drug antibiotic regimen.

Results
MRI showed an extradural, contrast-enhancing mass at C2–C4 compressing the spinal cord. Histopathology revealed pyogranulomatous steatitis; standard stains were negative for mycobacteria. PCR identified Mycobacterium DNA. Postoperative recovery was rapid; long-term antibiotic therapy resulted in full neurological recovery sustained for at least 20 months. Transient cutaneous lesions and later congestive heart failure occurred but were not linked to the mycobacterial infection.

Limitations
Species-level identification of Mycobacterium was not achieved due to the absence of culture. Potential dissemination was not fully excluded, and cutaneous signs were not definitively diagnosed. These limitations underscore the need for broader diagnostic workups in future cases.

Conclusions
This is one of the first documented cases of mycobacterial epidural steatitis in cats, expanding the known clinical spectrum of feline mycobacteriosis. PCR proved essential in diagnosis when traditional methods failed. Prompt surgical decompression and targeted antibiotic therapy can lead to favorable outcomes, highlighting the importance of early recognition and aggressive management.

Sagittal and transverse MRI images of the cervicothoracic region demonstrating an extradural mass lesion. Sagittal T2w (1a), T1w (1b), and post-contrast T1w (1c) sequences depict an elongated extradural lesion that is heterogeneously hyperintense on T2w and T1w images compared to spinal cord parenchyma, with strong homogeneous contrast enhancement (green arrows). The lesion is dorsal to the spinal cord, effacing the dorsal cerebrospinal fluid and fat column, with suspected mild spinal cord compression. Transverse T2w (2a), T1w (2b), gradient echo (2c), and post-contrast T1w (2d) sequences at the level of C2 vertebra reveal a crescent-shaped extradural T2w and T1w heterogeneously hyperintense strongly contrast enhancing lesion, predominantly occupying the right lateral and dorsal epidural space, with associated meningeal contrast enhancement (green arrows). The spinal cord appears T2w hyperintense (2a). Transverse T2w (3a), T1w (3b), gradient echo (3c), and post-contrast T1w (3d) sequences at the level of C3 vertebra demonstrate a similar extradural, moderately compressive lesion (green arrows). Punctate intralesional signal voids are visible on gradient echo images (3c). Concurrent meningeal and dorsal vertebral arch contrast enhancement is noted, and the spinal cord exhibits T2w hyperintensity.

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