Assessment of a scoring system for Basal Cell Carcinoma with multi-beam optical coherence tomography

Multi-beam optical coherence tomography (OCT) is a novel method of non-invasive skin imaging allowing the evaluation of tissue at high level of lateral and axial resolution. It permits the horizontal and vertical evaluation of the extent of diseases.

Herein, we aimed to validate diagnosing basal cell carcinoma (BCC) by OCT using a newly developed scoring system ('Berlin Score'-BS). This was based on the predetermined criteria such as dark border underneath the tumour and ovoid structures. Their frequency and distribution in subtypes of BCC were evaluated.

The study was conducted in two phases, in which the experience of examiner differed. A total of 127 BCC and 50 other skin diseases were examined. In phase one, students performed the evaluation of skin lesions using the BS, while in phase two an expert performed the scoring in a different subset of patients.

Application of BS by students revealed sensitivity and specificity of 92.8% (95% CI 85.4-96.8) and 24.1% (95% CI 11.0-43.4) when reaching the lower threshold BS≥8. The most common BCC subtypes were superficial (28.7%) and nodular (22.6%) BCC. Second phase was carried out to verify collected data by a dermatological specialist and expert in using OCT. Increased sensitivity and specificity for OCT amounted to 96.6% (95% CI 80.4-99.8) and 75.2% (95% CI 52.5-90.9). Thereby 88% of all diagnoses were correctly classified confirmed by histopathology.

Multi-beam optical coherence tomography revealed to be a fast and promising device for assessing lesions by means of BS. Both students, who benefit from practice in handling OCT, and experts are able to perform this procedure. However, experience and training in the interpretation markedly increased sensitivity and specificity of the BS in our study. Moreover, redefinition and refining of the criteria seems necessary and may further increase the diagnostic value of OCT for NMSC.