Background: Lichenoid keratosis (LK) is a well-described entity that has been proposed to represent a regressive response to a pre-existent epidermal lesion.
Aims: To evaluate the natural evolution of a series of cases showing the intermediate stage of the regression of seborrheic keratosis in LK using sequential dermoscopy imaging over time.
Material and methods: A series of lesions with dermoscopic areas of seborrheic keratosis and LK in the same tumor were consecutively collected for over 3 years at the Dermatology Department of the Hospital de Sant Pau i Santa Tecla, Tarragona, Spain. Sequential dermoscopic images of each case were collected quarterly for 1 year. At the end of the follow-up, all the lesions were biopsied.
Results: A total of 22 cases were collected. At the end of the follow-up, the LK part increased in all the lesions. In 11 cases (50%), the seborrheic keratosis part disappeared completely, and in another 5 cases (22.7%), seborrheic keratosis comprised only 10% of the remaining area.
Conclusions: These dermoscopic study findings support the proposal that LK represents a regressive response to a pre-existent epidermal lesion, in this case seborrheic keratosis.