Interrogating the Impassable: A Case Series and Literature Review of Unilateral SPECT-CT Groin Visualization in Men With Penile Cancer.

Penile squamous cell carcinoma (SCC) is a rare malignancy, which is known to invade local inguinal lymph nodes prior to progressing to the pelvis. Dynamic sentinel lymph node biopsy (DSLNB) is a standard for the minimally invasive assessment of lymphadenopathy in patients with subclinical groin metastasis. Hybrid 99mTc Single-Photon Emission Computed Tomography (SPECT-CT) has been shown to increase the accuracy of identifying first draining "sentinel" nodes (SN). Unilateral inguinal visualization on SPECT-CT is a rare presentation, which may increase the likelihood of a false negative SN biopsy. Retrospective analysis from three-penile cancer uro-oncologists in Melbourne, Australia identified 78 groins undergoing DSLNB for intermediate/high risk primary disease. Unilateral SPECT-CT results were observed in four patients suggesting a functional pattern of lymph diversion. Analysis confirmed malignancy (n = 2), sarcoidosis (n = 1), and evidence of local inflammation in SPECT-CT negative groins. Findings re-iterate the role of SPECT-CT a pre-operative adjunct. Experienced multimodal groin assessment using palpation, SPECT-CT, lymphoscintigraphy, and blue dye tracking remains paramount. Unilateral SN on pre-operative SPECT-CT in men with intermediate/high-risk penile SCC should elicit a higher degree of clinical suspicion. We recommend a low threshold for recommending radical inguinal lymph node dissection (ILND) for groins refractory to minimally invasive assessment.