Line-field optical coherence tomography: in vivo diagnosis of basal cell carcinoma subtypes compared with histopathology

Background Basal cell carcinoma (BCC) is the most common skin cancer in the general population. Treatments vary from Mohs surgery to topical therapy, depending on the subtype. Dermoscopy, reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) have gained a foothold in daily clinical practice to optimize diagnosis and subtype-oriented treatment. The new technique of line-field confocal OCT (LC-OCT) allows imaging at high resolution and depth, but its use has not yet been investigated in larger studies. Aim To evaluate the main LC-OCT criteria for the diagnosis and subtyping of BCC compared with histopathology, OCT and RCM. Methods In total, 52 histopathologically confirmed BCCs were evaluated for imaging criteria. Their frequency, predictive values and ROC curves were calculated. A multinominal regression with stepwise variables selection to distinguish BCC subtypes was performed. Results Nodular BCCs were mainly characterized by atypical keratinocytes, altered dermoepidermal junction (DEJ), tumour nests in the dermis, dark clefting, prominent vascularization and white hyper-reflective stroma. Superficial BCCs showed a thickening of the epidermis due to a series of tumour lobules with clear connection to the DEJ (string of pearls pattern). Infiltrative BCCs were characterized by elongated hyporeflective tumour strands, surrounded by bright collagen (shoal of fish pattern). The overall BCC subtype agreement between LC-OCT and conventional histology was 90.4% (95% CI 79.0-96.8). Conclusion LC-OCT allows noninvasive, real-time identification of BCCs and their subtypes in vertical, horizontal and three-dimension mode compared with histology, RCM and OCT. Further larger studies are needed to better explore the clinical applications of this promising device.

Automated summary

LC-OCT can be used for diagnosis and subtyping of BCC, with an overall agreement of 90.4% with histology. Nodular BCCs are characterized by atypical keratinocytes, altered DEJ, tumour nests in the dermis, dark clefting, prominent vascularization and white hyper-reflective stroma; Superficial BCCs show epidermal thickening with a series of tumour lobules connecting to the DEJ (string of pearls pattern); Infiltrative BCCs are identified by elongated hyporeflective tumour strands surrounded by bright collagen (shoal of fish pattern).