Prognostic factors for in-transit metastasis in patients with malignant melanoma

BACKGROUND AND AIMS: Malignant melanoma represents an aggressive and unpredictable malignancy, with high locoregional recurrence rates, regardless of tumor stage and therapeutic management. This study aims to identify the main histopathological prognostic factors involved in the development of in-transit metastasis in patients with malignant melanoma. METHODS: The study includes only patients that were diagnosed with malignant melanoma and with histologically confirmed in-transit metastasis who were treated in a comprehensive cancer center between 2010–2021. Histopathological parameters were investigated, univariate and multivariate analysis was performed. RESULTS: A total of 26 patients were included in the analysis. On univariate and multivariate analysis, only primary cutaneous melanomas located on the thorax correlated with the risk of developing in-transit metastasis, whereas clinicopathological factors such as an increased Breslow thickness and Clark level, the presence of ulceration, positive lymph nodes, a non-brisk TIL density, a high mitotic rate, a nodular subtype, and age >50 years may represent risk factors, even though we could not find any correlations. CONCLUSIONS: Primary cutaneous melanomas that arise on the thorax present a high risk for the occurrence of locoregional disease, whereas other clinicopathological characteristics could not be used to predict local recurrence. However, prospective and more extensive cohort studies are needed in order to validate these important prognostic factors.