Growth rate of clinically diagnosed superficial basal cell carcinoma and changes in dermoscopic features over time

Basal cell carcinoma (BCC) is the most commonly occurring skin cancer. BCCs have been found to generally grow slowly. Data are limited on how the dermoscopic characteristics of BCCs evolve. We set out to determine the growth rate of superficial BCCs (sBCC) and assess the change in dermoscopic features over time.

A retrospective review was performed of clinically diagnosed sBCC. Images, demographic and dermoscopic data were collected by a melanographer. Mixed effects linear regression models were used to investigate sBCC growth and associations between size and dermoscopic/demographic variables. We tested differences in trends over time in dermoscopic features using non-parametric trend tests.

100 individual sBCC were evaluated in 70 patients (mean age 62; 59% male), 69% had Fitzpatrick skin phototype 1 or 2, and 81% had some degree of actinic damage. sBCC were present on the back in 58% and 22% of men and women, respectively. The median surface area was 41.9 mm² with a growth rate of 0.81 mm² /month. Males had larger sBCC than females. There was no association between sBCC size and Fitzpatrick skin phototype, history of skin cancer or family history of melanoma. There is some evidence larger sBCC gain shiny white structures (P = 0.053) over time.

sBCC grow at a rate unlikely to adversely affect patient outcomes associated with long wait times. Our data suggest that dermoscopy can aid in appropriate treatment selection for sBCC.