Spontaneous regression in melanomas is not an uncommon phenomenon, as it has been described in 10-35% of primary cutaneous lesions . Regression does not appear to predict a more favorable course, since even fully regressed melanomas may progress into metastatic disease . Several dermoscopic features have been correlated with the regression process, including white scar-like depigmented areas and gray-blue, pepper-like granules, which correspond to dermal scarring, pigment incontinence and presence of melanophages [3,4]. Regression may occur not only in melanomas, but also in melanocytic nevi, which similarly may exhibit white areas and gray-blue granules or areas under dermoscopy . Overall, white areas have been proposed to be associated with the fibrosis type of regression and gray-blue areas to the melanosis type of regression of melanocytic tumors . Lichen planus like keratosis (LPLK) is considered to represent a regressed solar lentigo or seborrheic keratosis. Dermoscopy of LPLK at the late stage of the regression process reveals a diffuse gray-blue granular pattern, similar to that observed in regressed melanocytic lesions . In this context, when evaluating skin lesions that exhibit high degree of regression, interpretation of dermoscopic findings may be problematic, especially when no other dermoscopic clues can be recognized.
Lallas, A., Apalla, Z., Moscarella, E., Zalaudek, I., Tzellos, T., Lefaki, I., … Argenziano, G. (2012). Extensive regression in pigmented skin lesions: a dangerous confounding feature. Dermatology Practical & Conceptual, 2(2). https://doi.org/10.5826/dpc.0202a08