Superficial BCCs grow slowly at a rate of about 0.81mm² per month which provides some reassurance that delays in management are not critical.

A New Zealand study reviewed clinical and dermoscopic images of 100 individual lesions from 70 patients that were followed for a number of years. As this was an image database review, the reasons for the delay in treatment were unable to be ascertained.

The study found the mean surface area of the lesions was 41.9mm² and typically larger in men than women.

Most lesions occurred in non-cosmetically sensitive sites – most commonly on the back (58%), leg (14%) and chest (14%) in men and the leg (32%), arm (22%) and back (22%) in women.

The study found larger sBCC size (>41.9mm²) was associated with having ‘shiny white structures’, ‘clods brown/blue concentric’ and ‘clods blue small’.

And larger lesions were more likely to have an increase in ‘shiny white structures’ over time while smaller lesions did not appear to gain additional dermoscopic features.

“Our study shows that superficial BCCs gain signs of deeper dermal involvement as they enlarge with minimal presence of these features in the initial lesions,” the study said.

“We therefore suggest that surgical excision be considered if dermoscopic signs of dermal involvement are present. If topical treatment is used, close follow-up is essential to ensure resolution, with consideration of biopsy or excision of the lesion should it persist or acquire features suggesting dermal invasion.”

However there was no evidence that patients were disadvantaged by not receiving treatment quickly.

“Our study supports the belief that sBCC is slow growing at a rate of less than 1 mm² per month. Therefore, delays in treatment of sBCC, due to long wait times, are unlikely to affect patient outcome in non-cosmetically sensitive sites. This is reassuring news for patients,” the study concluded.

Lead author Dr Adrian Sykes, from the dermatology department at Waikato Hospital in Hamilton, told the limbic sBCCs were often not noticed until the lesions had grown large and started to bleed or ulcerate.

“Luckily, on non-cosmetically sensitive sites, treatment may not be very different even when delayed by a year or two,” he said.

However he noted that BCCs on facial skin had different characteristics.

“It is always disappointing when patients present late with these as treatment becomes more complicated and invasive. They are not always straightforward to diagnose so delays do occur despite the best of intentions.”