Peculiarities of lymphatic drainage in cutaneous malignant melanoma: clinical experience in 75 cases

In the recent years, the identification and biopsy of the sentinel lymph node (SLN) has become standard in the treatment of cutaneous malignant melanoma (CMM). In order to correctly apply the technique and to decrease the risk of false negatives,it is compulsory to track the lymphatic drainage of the primary tumor and to detect all SLN, regardless of their site.

At the Bucharest Oncologic Institute, over the last three years, selective lymphadenectomy was performed in 75 patients with CMM, stages I and II (AJCC). In 39 cases, the primary tumor was at the level of the upper and lower limbs and in 36 on the trunk. In all patients, lymphoscintigraphy was performed through intradermal injection of Nanocoll,with dynamic follow up of the radiotracer, with the purpose of finding the possible unusual locations of the SLN.

The sentinel lymph nodes were identified in 100%of the cases. In 63 patients (84%), the primary tumor drained in only one lymphatic field and in the other 12 the drainage was towards 2 or more lymphatic basins. The CMM situated on the trunk had a particular behaviour, presenting more often (33%) with multiple nodal basin drainage.

CMM of the trunk, mostly those situated close to the midline, but others as well, tend to drain into several lymphatic areas. The existence of interval lymph nodes and atypical lymphatic drainage, in a minor lymphatic basin,must be determined preoperatively in order to allow the biopsy of all SLN and establish the right therapy.