Anatomy of the cutaneous lymphatic system of the trunk: a clinico-anatomical study of 90 cutaneous melanomas

The cutaneous lymphatic system of the trunk is a complex network, the anatomical knowledge of which remains unclear. The lymphatic system plays a major role in the dissemination of lymphophilic cancers like melanomas. The aim of this study was to improve our knowledge, optimize the care of patients with cutaneous tumors of the trunk, and to use our clinical experience of the topography of pathologic lymph nodes related to cutaneous melanomas and depicted by lymphoscintigraphy. This prospective study included 90 consecutive patients who had primary resection of cutaneous melanoma of the trunk between June 2011 and January 2015. All patients had lymphatic mapping by lymphoscintigraphy, followed by sentinel lymph node procedure. We compared data of lymphatic imaging (lymphoscintigraphy and SPECT-CT) and surgery. We divided the trunk into 36 regions based on cutaneous anatomical landmarks to determine the topography of the lymphatic system for each tumor. Our study showed cutaneous lymphatic drainage of melanomas of the trunk in 16 different areas. This drainage could be single or multiple. We observed that drainage could be controlateral in medial regions of the trunk, and lymphatic pathway could be retrograde. This drainage could be bilateral for medial regions and mainly into axillary areas for regions above L1 level. Posterior regions of the trunk had more diversity of drainage areas than anterior regions. Cutaneous lymphatic drainage of the trunk was not limited to axillary and inguinal areas, showed interindividual variability, and was single or multiple, unilateral or bilateral, and unpredictable.