Expression of IMP3 in a retrospective cohort of melanomas with selective lymph node biopsy

Insulin-like growth factor-II mRNA-binding protein 3 (IMP-3), which is a member of the insulin-like growth factor mRNA-binding protein family, is expressed at high levels in many types of cancer, where it plays an important role in cell proliferation, as well as in the processes of invasion, migration, and metastasis. Its expression has also been demonstrated in malignant melanoma, but not in other benign skin lesions, which has raised the possibility of using it as a predictive and prognosis marker. Its relationship with sentinel lymph node biopsy, however, has not been explored yet. A retrospective study including 120 histological samples of patients diagnosed with malignant cutaneous melanoma in Granada, between 2012 and 2018, was developed. All patients had had a sentinel lymph node biopsy (SLNB) performed at Hospital Universitario San Cecilio. IMP3 immunostaining was simultaneously carried out in the cutaneous lesion. We observed a significant difference regarding the percentage of cells expressing IMP3 (29.73 ± 3.81 for negative SLNB vs 44.86 ± 5.91 for positive SLNB, P = .020). Our endpoint calculated according to the ROC curve of 35% was significant with P = .007. H (P = .013) and AR (P = .016) indexes, created by the percentage of positive tumor cells and the intensity of the IMP3 expression, were also statistically significant. The most optimal cut-off points to predict the positivity of the SLNB were 35 for the percentage of positive tumor cells and 70 for the H score. We found a significant association between the expression of IMP3 and the regional nodal status defined by the SLNB on malignant melanomas in our series.