Line-field confocal optical coherence tomography of basal cell carcinoma: a descriptive study

Background: Early diagnosis and subtype classification of basal cell carcinoma (BCC) are crucial to reduce morbidity and optimize treatment. Good accuracy in differentiating BCC from clinical imitators has been achieved with existing diagnostic strategies but lower performance in discriminating BCC subtypes. Line-field confocal optical coherence tomography (LC-OCT) is a new technology able to combine the technical advantages of reflectance confocal microscopy and OCT. Objectives: To identify and describe LC-OCT criteria associated with BCC and explore their association with BCC subtypes. Methods: Basal cell carcinoma were imaged with a handheld LC-OCT device before surgical excision. LC-OCT images were retrospectively evaluated by three observers for presence/absence of criteria for BCC. Multivariate logistic regression models were used to find independent predictors of BCC subtypes. Results: Eighty-nine histopathologically proven BCCs were included, of which 66 (74.2%) were pure subtypes [superficial BCC (sBCC): 19/66 (28.8%); nodular BCC (nBCC): 31/66 (47.0%); infiltrative BCC (iBCC): 16/66 (24.2%)]. Lobules, blood vessels and small bright cells within epidermis/lobules were the most frequent criteria for BCC. LC-OCT criteria independently associated with sBCC were presence of hemispheric lobules, absence of lobule separation from the epidermis, absence of stretching of the stroma; with nBCC were presence of macrolobules, absence of lobule connection to the epidermis; and with iBCC were presence of branched lobules. Conclusions: This was the first study describing the characteristics of BCC under LC-OCT examination. We proposed morphologic criteria, which could be potentially useful for diagnosis and subtype classification of BCC, as well as for its therapeutic management. Future studies are needed to assess these hypotheses.