Lymphatic drainage of calf melanoma skipping the superficial groin

Background. Metastases of melanoma often follow predictable patterns of lymphatic drainage. However, some cases demonstrate first-echelon drainage to an unexpected basin. We describe a patient with drainage from melanoma on the calf to a sentinel lymph node in the iliac basin. Methods and Results. Biopsy of the sentinel lymph node was guided by preoperative lymphoscintigraphy and intraoperative use of a gamma probe and blue dye. The node excised from the iliac basin showed evidence of metastasis. Conclusion. The failure to detect aberrant sentinel lymph nodes and bypassed basins may lead to improper assessment of disease stage and deficient patient management.