Epidural abscess and facet joint septic arthritis
Bilateral L5-S1 radiculopathy, left greater than right.
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A large epidural collection is present extending from L3/4 down to S1/2 with very prominent surrounding enhancement and multiple non-enhancing fluid attenuating central locules largest of which is centred behind L5 and measures 31 x 7 x 12 mm. It is not possible to visualise the cauda equina at this level although the theca appears to be displaced anteriorly and somewhat to the left. There appears to be enhancement of the cauda equina at these levels consistent with arachnoiditis.
Enhancement extends superiorly to the T10/11 level (top of the scan) where it is located posterior to the theca and is thin. The vertebral bodies and discs are unremarkable, with no evidence of discitis/osteomyelitis although a small amount of oedema is demonstrated at the posterosuperior corner of the L4 vertebral body.
The right L3/4 facet joint is clearly abnormal, and appears to be the epicentre of a great deal of oedema and enhancement in the surrounding musculature. There number of peripherally enhancing centrally fluid attenuating collection is related to the facet joint, the largest of which is dorsal and inferior and measures 10 mm in diameter. Oedema in the musculature extends up to the L1 vertebra and down to the S1 level. Some oedema is also demonstrated in the right psoas muscle without evidence of an established psoas abscess.
Extensive epidural phlegmon, with multiple epidural abscesses secondary to advanced septic arthritis of the right L3/4 facet joint with associated small paraspinal musculature abscesses. Cauda equina compression and likely arachnoiditis.
The patient went on to have a laminectomy.
The sections show ligamentum flavum, calcified lamellar bone and adjacent connective tissue. There are collections of neutrophils, surrounded by chronic inflammatory cells and fibrosis. No granulomas are seen. There is no evidence of malignancy. The Gram stain shows sparse Gram positive bacterial cocci in the inflammatory exudate.
Organising abscess formation.