What is the cause of the patient's presentation?
A ureteric calculus in the right distal ureter.
What management is necessary?
It is a small stone, almost certain to pass. Analgesia and hydration should suffice.
What incidental finding is present?
Swollen, stranded mesentery with multiple soft tissue nodules.
What is the likely diagnosis and what sign elegantly illustrated here is reassuring that this is in fact the diagnosis?
Mesenteric panniculitis. The soft tissue nodules and vessels are surrounded by a halo of clear (non-stranded) fat. This is known as the fat ring sign (or fat halo sign) and is said to not be present in malignant causes of mesenteric stranding and lymphadenopathy.
Note is made of a small stone at the distal right ureter causing mild hydroureteronephrosis.
Incidental finding of stranding and swollen mesentery containing multiple tissue nodules, with preserved fat around the mesenteric vessels and the soft tissue nodules.