Tumoral inflammatory infiltrate does not predict metastases in thin primary cutaneous melanomas

In cutaneous melanomas in general, tumor inflammatory infiltrate (TII) can protect against distant metastases, but there is no consensus when only thin primary cutaneous melanomas (TPCM) are considered.

To investigate the presence of TII in TPCM and the relationship between TII and the occurrence of metastases.

Case-control study including 50 patients with TPCM, 22 metastatic (MC group) and 28 non-metastatic (NMC group). The presence of TII was evaluated and, if present, qualified as mild, moderate or marked.

The mean age was 50.7 years in the MC and 56.2 years in the NMC group (p = 0.234), and the male sex predominated in the MC group (63.6%). The average Breslow thickness was higher in the MC when compared to that observed in the NMC (respectively 0.8 vs. 0.6 mm, p = 0.012). The presence of ulceration occurred in 22.7% of the MC and 17.9% of the NMC (p = 0.732). TII was present in all 50 TPCM, being marked or moderate in 67.9% of the NMC and 54.5% in the MC group (p = 0.503). In the multivariate analysis, the presence of moderate and marked TII had an Odds Ratio (OR) of 0.57 (95% Confidence Interval [CI]: 0.18‒1.8) and adjusted OR of 0.68 (95% CI 0.13‒3.99).

Small sample size.

TII was present in all TPCM (with and without metastases), and it was not possible to demonstrate a protective effect of TII against the appearance of metastases.