case_images: PMC8554084_01
case_images: Right lateral abdominal (A), ventrodorsal coxofemoral joint (B) radiographs, and abdominal ultrasound depicting sublumbar lymph node (C). (A) Irregular ventral margin of the 4th lumbar vertebra (white arrowhead) and decreased serosal detail are found. (B) Left sacroiliac joint is radiolucent and its bone margin (black arrowhead) is indistinct. (C) Enlarged sublumbar lymph node (white arrow) and anechoic trapped retroperitoneal fluid (asterisk) are noted.
case_images: fvets-08-732788-g0001.jpg
case_images: PMC8554084_01_fvets-08-732788-g0001.jpg
case_images: F1
case_images: However, abdominal radiography revealed irregular ventral margin of 4th lumbar vertebra and decreased abdomen serosal detail (Figure 1A). Additionally, coxofemoral joint radiography revealed radiolucent left sacroiliac joint with indistinct bone margins, indicating bone lysis (Figure 1B). Medical System, Tokyo, Japan) with linear-array (10 MHz) probe revealed bilateral sublumbar and inguinal lymphadenopathy (Figure 1C). Moderate amount of trapped anechoic fluid was found in the retroperitoneal space, adjacent to enlarged sublumbar lymph nodes.
case_images: Transverse plane, pre-contrast CT image (A) and dorsal plane, pre-contrast CT image (B) in bone algorithm at the level of sacroiliac joint level. (A) Compared to right sacrum and ilium, left sacrum (white arrowhead), and ilium (black arrowhead) have relatively low attenuation and indistinct bone margins. Left gluteal (asterisk) and sublumbar muscle (double-asterisk) show marked swelling and increase in thickness. Note widening of retroperitoneal space. (B) Low attenuation of left sacrum (white arrowhead) and ilium (black arrowhead) are noted.
case_images: fvets-08-732788-g0002.jpg
case_images: PMC8554084_01_fvets-08-732788-g0002.jpg
case_images: F2
case_images: Left sacral bone and ilium exhibited lower bone attenuation compared to the right sacral and ilium (Figure 2). Left sublumbar muscles, including psoas major and psoas minor, were edematous and thickened (Figure 2A).
case_images: Transverse T2W image (A), pre-contrast T1W image (B), post-contrast T1W image (C) at the level of L7-S1 intervertebral space and T2W image (D) at the level of sacroiliac joint. Sagittal T2W image (E) of the lumbar spinal cord and post-contrast T1W images (F) of the lumbar spinal cord. (A-C) T2W hyperintense, T1W hypointense, and contrast-enhanced T1W rim enhancing structure (asterisk) located at ventral of the lumbar vertebral body represents retroperitoneal abscess. (D) Retroperitoneal abscess (white long arrow) is found at the level of sacroiliac joint. Muscular abscess (white short arrow) is also indicated. Compared to the right sacral bone, left sacral (white arrowhead) and iliac bone (black arrowhead) are T2W hyperintense and indistinct left sacroiliac joint space, which is consistent with sacroiliitis. Left gluteal, sacrocaudal, and sublumbar muscle (double asterisk) show marked swelling, T2W hyperintense, and enhanced on contrast-enhanced T1W. (E) No abnormality is noted in the lumbar spinal cord of the T2W sagittal image. (F) Compared to other regions of lumbar spinal cord, mildly increased intensity of the spinal cord at the level of L7-S1 is shown (arrowheads) at post-contrast T1W. This could represent true enhancement but also could be due to slice thickness artifact.
case_images: fvets-08-732788-g0003.jpg
case_images: PMC8554084_01_fvets-08-732788-g0003.jpg
case_images: F3
case_images: NJ, USA). No remarkable changes were noted in lumbar spinal cord on T2W images (Figure 3D) but intensity of the spinal cord at the level of L7-S1 was mildly increased on post-contrast T1W images (Figure 3F). Hyperintense left sacrum and ilium on T2W images and indistinct left sacroiliac joint space were noted (Figure 3D). Also, ill-defined and thickened gluteal muscle appeared hyperintense on T2W images and strongly enhanced on T1W contrast-enhanced images (Figures 3A,C). Retroperitoneal space at level of lumbosacral joint exhibited T1W hypointense, T2W hyperintense, contrasted-enhanced T1W rim enhancing hypointense lesion with distinct margin (Figure 3).
case_images: Musculoskeletal ultrasound images of the sacroiliac joint (A,B) and cytologic evaluation of aspirated trapped fluid around the iliac wing (Wright-Giemsa stain, x400 magnification) (C). (A) Adjacent to left iliac wing, lytic changes of left sacral bone (asterisk) is noted. (B) Trapped anechoic fluid (white long arrow) and hyperechoic muscle (double asterisk) are found in the retroperitoneum near left iliac wing. (C) Cytologic evaluation indicates numerous degenerated neutrophils and phagocyted cocci.
case_images: fvets-08-732788-g0004.jpg
case_images: PMC8554084_01_fvets-08-732788-g0004.jpg
case_images: F4
case_images: Bone lysis of the left sacrum and the iliac wing was noted (Figure 4A). Anechoic trapped fluid and hyperechoic muscles adjacent to iliac wing were also observed, which indicated myositis (Figure 4B). Pyogenic fluid was aspirated and cytologic examination demonstrated myeloblast, numerous degenerated neutrophils, and phagocyted cocci (Figure 4C).