Tender thigh in a patient with Crohn's disease

Answers

There are relatively large pockets of air seen in the soft tissue lateral to the right hip joint, which may indicate the formation of abscesses, probably caused by gas-forming organisms, or that have a fistulous communication with the bowel. Both hip joints are unremarkable.
Necrotizing fasciitis always needs to be considered and ruled out.
This patient needs i) urgent ICU admission, ii) hemodynamic resuscitation, iii) a septic screen, iv) broad-spectrum antibiotic coverage, v) laboratory investigations including muscle enzyme assays, vi) orthopedic and infectious disease teams to be involved, vii) diagnostically and therapeutically monitored drainage of the abscesses, in addition to special care and management of his Crohn's disease including viii) stool testing for culture and Gram staining, ova and parasites, and C. diffficle toxin and CMV antigenemia. At a later stage, his fistulizing disease needs to be evaluated with MRI of the abdomen and pelvis, and antiTNF therapy needs to be tried after ruling out sepsis. Colorectal surgeons need to be consulted if he does not respond.