Kretschmer L, Mitteldorf C, Hellriegel S, et al. - Researchers undertook this retrospective cohort analysis to determine prognostic significance of melanoma infiltration of several anatomically defined lymph node substructures. Within the sentinel lymph node (SN) with the highest tumor burden, SN invasion level (SNIL) was described as follows: SNIL 1 = melanoma cells restricted to intracapsular lymph vessels, subcapsular or transverse sinuses; SNIL 2 = melanoma infiltrating the cortex or paracortex; SNIL 3 = melanoma infiltrating the medulla or capsule. SN-positive population was categorized by SNIL into three groups with significantly varied recurrence-free survival, melanoma-specific survival (MSS), and nodal basin recurrence likelihoods. Virtually identical MSS was found among patients with SNIL 1 vs SN-negative patients, whereas a very poor prognosis was indicated by outgrowth of the metastasis from the parenchyma into the fibrous capsule or the medulla of the lymph node. Therefore, experts inferred the likely utility of SNIL in assisting a better evaluation of the benefit-risk ratio of adjuvant therapies in cases with different SN metastasis patterns.