MELTUMP, SAMPUS rarely lead to metastatic malignancies

There appears to be low to no metastatic potential for melanocytic tumours of uncertain malignant potential (MELTUMP) and superficial atypical melanocytic proliferations of uncertain significance (SAMPUS), a recent study has found.

Researchers conducted a retrospective cohort analysis of 1,685 patients with MELTUMP and 1,957 with SAMPUS, whose data were retrieved from the Dutch Nationwide Pathology Databank from 1991 to 1 October 2021. All participants were examined for clinical outcomes. The 3,642 lesions assessed in total occurred in 3,535 patients.

Most patients (97.7 percent) presented with one lesion, while three had a maximum of five lesions each. Melanoma had previously occurred in 14.8 percent of patients with MELTUMP and 23.0 percent of those with SAMPUS. Most lesions arose on the trunk. Participants were mostly female (59.7 percent).

MELTUMP was first diagnosed in 2006 and showed an increasing trend before stabilizing in 2012, at a rate of 150 diagnoses per year. Similarly, SAMPUS diagnoses increased over time, peaking at around 300 diagnoses per year in 2016.

Data for disease course analysis was available for 2,692 cases, of which only 1.6 percent showed evidence of local recurrence, local progression to melanoma, or metastatic behaviour. Of these, 29 were cases of MELTUMP and 15 were of SAMPUS. The median time to recurrence or progression was 33.0 months.

Metastatic behaviour was reported in only 0.7 percent of MELTUMP patients and in 0 percent of those with SAMPUS.