A 17-year-old young woman presented to the chronic pain clinic complaining of left buttock pain that radiated down to her left knee.  She described her left leg as aching and feeling heavy.  Other than taking an oral contraceptive for dysmenorrhea, she was otherwise healthy.

Her physical exam was notable for positive faber and fair maneuvers.  No allodynia, tender points, trigger points, or trochanteric bursitis were appreciated.  Her left leg had venous varicosities and appeared dusky with coolness to the touch compared to the right.  Images revealed no neuroforaminal narrowing, normal piriformis and sciatic nerve and no sacroiliitis noted but an abnormality in venous drainage was noted, that would be better correlated with a pelvic CT. 

Which of the following syndromes is most suggested by the presentation outlined above?