Significance of Primary Melanoma Regression on Local Infiltrate and Outcome

Introduction: The characteristics and the prognostic value of regression in primary melanomas are controversial.

Objectives: To further characterize "hot" and "cold" tumor's stromas and to investigate the association between dermoscopy, pathology, and the prognostic implications of regression.

Methods: A 14-year-collection-based retrospective analysis was carried out on 40 patients with confirmed regressive melanomas.

Results: The extent of regression in dermoscopy was associated with the stage of the regression (P = 0.05) and with the MelanA patterns in histology (P = 0.02). Blue-gray and gray-brown color of the peppering (P = 0.01), and the eccentric, multifocal character of the dermoscopic regression (P = 0.05) were associated with "hot" stromas (CD8+, Granzym B+). Focal histologic regression (regressing melanomas) was associated with a good outcome (P < 0.001), while a complete regression (regressed melanomas) was associated with melanoma-related death (P < 0.001). "Hot" stromas (CD8⁺ were significantly associated with survival at 10 years (P = 0.044), while "hot" stromas (Granzyme B⁺) were associated with the locoregional extension (P = 0.016), and the initial distant metastasis (P = 0.016).

Conclusions: Dermoscopic features of regression in primary melanomas were associated with the stage of regression, its extent, and the "hot" or "cold" nature of the tumor stroma, with prognostic implications.