Delayed lymphoscintigraphy for sentinel node mapping following wide local excision in primary melanoma

Sentinel lymph node biopsy (SLNB) is used in the staging of melanoma and is generally performed at the time of wide local excision (WLE) of the primary lesion, the location of which guides preoperative and intraoperative lymphatic mapping. However, the role of delayed lymphatic mapping following prior WLE remains unclear. We report the case of a patient who underwent lymphoscintigraphy before and after WLE for melanoma, compare the findings, and review the published literature. A 32-year-old woman was scheduled for WLE and SLNB of a 2.0-mm Breslow thickness melanoma on the upper arm. After her preoperative lymphoscintigram, an unplanned pregnancy was diagnosed, and she elected to proceed with WLE alone. She later requested delayed SLNB and underwent a second lymphoscintigram 2 months later. Comparison of the pre- and post-WLE lymphoscintigrams demonstrated variation in the location and number of sentinel lymph nodes, raising important questions about the accuracy of delayed lymphatic mapping and SLNB in melanoma. This report adds to the understanding of lymphatic channel behavior following WLE and may help inform decision-making for patients and clinicians.