Line‐field confocal optical coherence tomography for actinic keratosis and squamous cell carcinoma: a descriptive study

Summary Background Early and accurate diagnosis of cutaneous squamous cell carcinomas (SCCs) and actinic keratoses (AK) is fundamental to reduce their associated morbidity and to select the correct treatment. Line‐field confocal optical coherence tomography (LC‐OCT) is a new imaging device that can characterize healthy skin and basal cell carcinoma, but no large studies on keratinocyte cell tumours have yet been published. Aim To identify and describe LC‐OCT criteria associated with SCC and AK, and to compare LC‐OCT findings in these tumours. Methods A retrospective observational multicentre study was conducted. Lesions were imaged with the LC‐OCT device before surgery and examined histologically. LC‐OCT criteria for AK/SCC were identified and their presence was evaluated in all study lesions. Univariate and multivariate analyses were performed to compare AK and SCCs, and to investigate differences between in situ and invasive tumours. Results In total, 158 patients with 50 AK and 108 SCCs (62 in situ and 46 invasive) were included. Cytological and architectural alterations were found in most lesions, and differences were found between AK and SCCs. Although the visualization of the dermoepidermal junction (DEJ) was often hampered by hyperkeratosis and acanthosis, an outlined DEJ without broad strands was observed in almost all AK and almost all in situ SCCs, but in only three invasive SCCs (P