title: Visualization of tumor blockage and rerouting of lymphatic drainage in penile cancer patients by use of SPECT/CT.
abstract: The reliability of sentinel node biopsy is dependent on the accurate visualization and identification of the sentinel node(s). It has been suggested that extensive metastatic involvement of a sentinel node can lead to blocked inflow and rerouting of lymph fluid to a "neo-sentinel node" that may not yet contain tumor cells, causing a false-negative result. However, there is little evidence to support this hypothesis. Recently introduced hybrid SPECT/CT scanners provide both tomographic lymphoscintigraphy and anatomic detail. Such a scanner enabled the present study of the concept of tumor blockage and rerouting of lymphatic drainage in patients with palpable groin metastases.
  
  
  METHODS
  Seventeen patients with unilateral palpable and cytologically proven metastases in the groin underwent bilateral conventional lymphoscintigraphy and SPECT/CT before sentinel node biopsy of the contralateral groin. The pattern of lymphatic drainage in the 17 palpable groin metastases was evaluated for signs of tumor blockage or rerouting.
  
  
  RESULTS
  On the CT images, the palpable node metastases could be identified in all 17 groins. Four of the 17 palpable node metastases (24%) showed uptake of radioactivity on the SPECT/CT images. In 10 groins, rerouting of lymphatic drainage to a neo-sentinel node was seen; one neo-sentinel node was located in the contralateral groin. A complete absence of lymphatic drainage was seen in the remaining 3 groins.
  
  
  CONCLUSIONS
  The concept of tumor blockage and rerouting was visualized in 76% of the groins with palpable metastases. Precise physical examination and preoperative ultrasound with fine-needle aspiration cytology may identify nodes with considerable tumor invasion at an earlier stage and thereby reduce the incidence of false-negative results.
authors.affiliation: Department of Urology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
authors.forename: Joost A P
authors.initials: JA
authors.lastname: Leijte
authors.forename: Iris M C
authors.initials: IM
authors.lastname: van der Ploeg
authors.forename: Renato A
authors.initials: RA
authors.lastname: Valdés Olmos
authors.forename: Omgo E
authors.initials: OE
authors.lastname: Nieweg
authors.forename: Simon
authors.initials: S
authors.lastname: Horenblas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005188:False Negative Reactions; D006119:Groin / Q000473:pathology*; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D010412:Penile Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D019275:Radiopharmaceuticals; D021701:Sentinel Lymph Node Biopsy; D013667:Technetium; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D013667:Technetium