Tumour regression does not increase the risk of sentinel node involvement in thin melanomas.

Few studies have analysed the relationship between tumour regression and risk of nodal metastasis in patients with thin melanomas (Breslow thickness < or = 1 mm), and the conclusions reported have been conflicting. The aim of this study was to evaluate the role of histological regression as a predictor of lymph node metasta- sis in a selected group of patients with thin melanomas, submitted to lymphatic mapping and sentinel lymph node biopsy. From November 1999 to November 2006, 59 patients with thin melanomas (28 females and 31 males; mean age: 58.7 years) underwent lymphatic mapping and sentinel lymph node biopsy. The mean Breslow thickness was 0.60 mm (range: 0.24-1 mm). Tumour ulceration was present in 2 patients (3.4%) and histological regression in 45 (76.3%). Sentinel lymph node metastases were detected in 2 of 59 patients (3.4%), but only one patient with a positive sentinel lymph node exhibited histological regression of his tumour. Therefore, the sentinel lymph node positivity rate in thin regressing melanomas was 2.2%. Literature data and our experience suggest that tumour regression is not a predictor of sentinel lymph node metastasis in patients with thin melanomas, and therefore does not justify the routine use of lymphatic mapping and sentinel lymph node biopsy in this melanoma setting.