Extra nodal growth as a prognostic factor in malignant melanoma

Extra nodal growth (ENG) in lymph-node metastases may be an additional indicator for poor prognosis and increased loco-regional recurrence in patients with a cutaneous malignant melanoma (CMM). Most studies analyzing prognostic factors lack a proper definition or description of the histological criteria for extra nodal growth. The objective of this study was to evaluate this factor.

Retrospectively 94 patients with CMM and clinically lymph-node metastases were analysed. Metastatic lymph-nodes were evaluated for ENG and if present grouped in microscopic (<2 mm) or macroscopic (>2 mm) ENG. ENG was defined as metastatic tumour which clearly extends histologically through the nodal capsule into the perinodal fatty tissue or tumour involvement in the hilar region with interruption of the smooth outline of the (presumed) capsule.

Ninety-four patients, median age 52 (6-92) years with CMM, median Breslow thickness 2.8 (0.2-11.0) mm. In 50 patients ENG was present (macroscopic: 32, microscopic: 18). The median follow-up was 59 (range 5-325) months. The number of loco-regional recurrence was 10; 4 in the group with and 6 in the group without ENG (n.s.). Five years survival of patients with ENG was 42% and without ENG 50% (n.s.). There was no significant difference in survival or loco-regional recurrence between microscopic or macroscopic ENG.

ENG of lymph-node metastases of CMM is of no prognostic value and has no clinical impact.