Anatomical Mapping of Lymphatic Drainage in Penile Carcinoma with SPECT-CT: Implications for the Extent of Inguinal Lymph Node Dissection

BackgroundKnowledge regarding the lymphatic drainage pattern of penile cancer is the basis for the extent of inguinal lymph node dissection for this disease.ObjectiveTo prospectively analyze the lymphatic drainage pattern of penile carcinoma using SPECT-CT and evaluate the implications for the extent of inguinal lymph node dissection.Design, Setting, and ParticipantsThe lymphatic drainage patterns of 50 patients scheduled for dynamic sentinel node biopsy were analyzed using a hybrid SPECT-CT scanner.MeasurementsA total of 86 clinically node-negative (cN0) inguinal and pelvic regions was evaluated. The sentinel and higher-tier nodes on SPECT-CT were divided into different zones in the groin and pelvic region. The groin was divided according to Daseler's five zones, four zones obtained by drawing a vertical and horizontal line over the saphenofemoral junction and one zone directly overlying this junction. The nodes in the pelvic region were classified into three zones: the external iliac/obturator zone, the common iliac zone, and the paraaortal zone.Results and LimitationsLymphatic drainage was visualised in 82 of the 86 cN0 groins (95.3%). A total of 115 sentinel nodes and 182 higher-tier nodes was found. All sentinel nodes were located in superior and central inguinal zones. The higher-tier nodes were located in the groin and pelvic region. No lymphatic drainage was seen to the inferior two regions of the groin. A potential limitation of the study is that the unilateral lymphatic drainage seen in some patients could be normal, but it could also be caused by blockage of lymphatic drainage due to a grossly involved metastatic lymph node. Another possible limitation is that this study relies on the quality and accuracy of lymphoscintigraphy and the subsequent sentinel node procedure.ConclusionsAll sentinel and higher-tier nodes were located in the superior and central inguinal zones and the pelvic region. No lymphatic drainage to the inferior inguinal zones was seen. This suggests that the extent of inguinal node dissection in cN0 patients could be reduced to removal of the superior and central inguinal zones. This may decrease the extensive morbidity associated with this procedure.