Sacrococcygeal chronic osteomyelitis - fistulising Crohn disease
Known history of Crohn's disease. Pelvic pain.
MRI Pelvis - perianal fistula protocol and extended sacrococcygeal imaging
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There is a supralevator trans-sphincteric fistula at 6 o'clock of the anorectal junction with a seton suture within the inferior branch and opening to the skin in the left natal cleft. Another branch is seen extending posteriorly to the coccyx and buttock, with inflammatory infiltrates in the presacral region and extending to the subcutaneous aspect of the posterior buttock in the midline. The subcutaneous granulation tissue in the midline of the posterior buttock is more prominent than the previous study (not shown).
Three persistent fibrotic trans-sphincteric tracts are identified at 3 o'clock, 9 o'clock, and 12 o'clock of the distal anus without collection.
Conclusion: Branched 6 o'clock supralevator trans-sphincteric fistula tract with one branch extending to the left natal cleft and seton in situ.
Another branch going to the coccyx with associated osteomyelitis.
More prominent inflammatory granulation tissue in the subcutaneous aspect of the posterior buttock near the midline.
No collection or other interval changes.
Microscopy: The sections show focally necrotic but largely viable cancellous bone. Within intertrabecular spaces, there is an increase in chronic inflammatory cells associated with reactive fibrosis. Granulomata are not seen. Convincing microorganisms are not identified on Gram, PAS or Ziehl Neelsen-stained sections. There is no evidence of malignancy.
Macroscopy: Labelled "Coccyx biopsy". Bone 15 x 3 x 2 mm.
Diagnostic Opinion: Coccyx: Features in keeping with chronic osteomyelitis. Please correlate with the results of microbiological investigations.