Image-guided percutaneous targeting of lymph nodes: a novel approach for salvage pelvic lymphadenectomy in recurrent prostate cancer

Recently, Torricelli et al. (1) published a video showing a step by step technique for salvage lymph node dissection after radical prostatectomy. With the development of novel imaging techniques, the identification of PCa patients with a clinical lymphonode (LN) relapse has become feasible. Salvage LN dissection (SLND) represents a treatment option for patients with prostate cancer relapse limited to the LN, with a potential beneficial impact of pelvic LN dissection on survival in these patients (2, 3). Usually a template extended SLND is performed, however the properly identification of the compromised LN is still a challenge and may be related to the treatment fail (3). We present a case of successful de novo SLND with image-guided percutaneous targeting LN using colloidal charcoal for recurrence detected by 68Ga-PSMA PET/CT following RP and previous salvage lymphadenectomy. Our patient is a 52-year old man with PCa diagnosed by transrectal ultrasound guided biopsy (Gleason 4+3 in 2/14 cores and 3+3 in 3 cores) with PSA: 4.58ng/dL and negative CT and bone scan who underwent retropubic radical prostatectomy and limited LN dissection [Pathology: PCa Gleason 8 (4+4) and 7 negative LN]. One month post-operatively the urinary continence and erectile function were recovered with PSA: 0.18ng/dL and 0.22ng/dL after 3 months. 68Ga-PSMA PET/CT revealed positive LN in the right obturatory region. Open SLDN was performed displaying 7 free LN. One month post-operatively the PSA was still elevated (0.82ng/ dL). A new 68Ga-PSMA PET/CT revealed the same suspected LN with higher SUV (Figure-1). De novo bilateral robotic SLDN was performed after percutaneous CT-guided targeting of 68Ga-PSMA PET/CT scan positive LN. The lesion was identified and 3mL of 4% solution of colloidal charcoal and lipiodol was injected into LN using a extraperitoneal lateral approach 20G needle (Figure-2). The rationale is to dilute a small amount of activated carbon into a thick substance to stabilize the material and prevent migration to adjacent structures, which may be an oil (such as ethiodinzed oil-lipiodol®) or a tissue adhesive (such as n-butyl-2-cyanoacrylate-histoacryl®) as we have preferred and recent data have been published (5). We found an inflammatory and stuck tissue around the blood vessels and ureter related with the two previous surgeries (Figure-3). In the right side an extended LN dissection was performed identifying the target LN previously tattoed close to the hypogastric artery distal to the umbilical artery. In the left side, a classic extended LN dissection was performed. Our operative time was just under 3 hours with an estimated blood loss of 150mL. JP drain was maintained until discharge on postoperative day 2. There were no intraoperative or postoperative complications. The final pathology revealed 1 of 4 positive LN on the right side. Three months follow-up revealed PSA<0.04ng/dL. Image-guided percutaneous targeting of lymph nodes: a novel approach for salvage pelvic lymphadenectomy in recurrent prostate cancer _______________________________________________