The working diagnosis following the US was "lymphoedema of unknown cause'
There is marked edema of the skin of the penis and scrotum bilaterally with enlarged nodes in both the right and left groins. There is a large complex lobulated rim enhancing fluid collection in the left buttock, superficial to the gluteus maximus muscle. This tracks anteriorly in the perineum towards the scrotum. There are also multiple abnormal gas pockets surrounding the anal region suggestive of fistulae. There is also thickening of the levator muscles. No free fluid in the pelvis. The rectum and sigmoid appear normal, also the bladder. No intrapelvic mass. No abdominal adenopathy.