Prognosis of patients with melanoma and microsatellitosis undergoing sentinel lymph node biopsy

Melanoma microsatellitosis is classified as stage IIIB/C disease and is associated with a poor prognosis. Prognostic factors within this group, however, have not been well characterized.

We performed a retrospective analysis of 1,621 patients undergoing sentinel lymph node (SLN) biopsy at our institution (1996-2011) to compare patients with (n = 98) and patients without (n = 1,523) microsatellites. Univariate and multivariate logistic and Cox regression analyses were used to identify factors associated with SLN positivity and melanoma-specific survival (MSS) in patients with microsatellites.

Patients with microsatellites were older and had lesions with higher Clark level and greater thickness that more frequently had mitoses, ulceration, and lymphovascular invasion (LVI) (all p < 0.0001). In microsatellite patients, the SLN positivity rate was 43 %. Lesional ulceration (odds ratio [OR] = 2.9, 95 % confidence interval [CI] 1.5-8.6), absent tumor infiltrating lymphocytes (OR = 2.8, 95 % CI 1.1-7.1), and LVI (OR = 3.3, 95 % CI 1.7-10) were significantly associated with SLN positivity by multivariate analysis. With a median follow-up of 4.5 years in survivors, ulceration (hazards ratio [HR] = 3.4, 95 % CI 1.5-7.8) and >1 metastatic LN (HR = 2.7, 95 % CI 1.1-6.6) were significantly associated with decreased MSS by multivariate analysis. In patients without these prognostic factors, the 5-year MSS was 90 % (n = 49) compared with 50 % (n = 23) among patients with ulceration only, 51 % (n = 12) in those with >1 metastatic LN only, or 25 % in those with both (n = 14, p < 0.01).

Microsatellitosis was frequently associated with multiple adverse pathologic features. In the absence of ulceration and >1 metastatic LN; however, the outcome for patients with microsatellites compared favorably to stage IIIB patients overall.