The role of reflectance confocal microscopy in the diagnosis and management of squamous cell carcinoma in situ treated with photodynamic therapy.

BACKGROUND

Reflectance confocal microscopy (RCM) is increasingly used for noninvasive in vivo diagnosis of skin cancers. We seek to determine if RCM is useful for the diagnosis and follow-up of squamous cell carcinoma in situ (SCCIS) posttreatment to document clearance.

METHODS

A pilot prospective study enrolled 10 patients with a total of 11 SCCIS lesions. Clinical, confocal, histological features and fluorescence diagnosis (FD) were recorded pre- and posttreatment.

RESULTS

Four SCCIS lesions underwent RCM imaging prior to biopsy, while 11 SCCIS lesions were followed up with RCM imaging. Clinical features of persistent SCCIS post-PDT in four out of 11 follow-up cases were confirmed with RCM and FD. There were no RCM features of SCCIS in seven lesions which were clinically cured. All eight (four new SCCIS and four follow-up) cases displayed atypical honeycomb pattern. Two cases (25%) showed numerous epidermal dendritic cells, while small bright refractive cells were present in the epidermis in two lesions (25%). Round blood vessels in the superficial dermis were seen in four lesions (50%), while three lesions (37.5%) showed dermal inflammatory cells.

CONCLUSION

There was good correlation between histological and confocal features in patients who underwent RCM imaging prior to biopsy. RCM may be a complementary tool in diagnosing SCCIS and to monitor response to nonsurgical treatment by avoiding unnecessary biopsies especially in lesions with persistent residual postinflammatory erythema.