Presurgical evaluation of basal cell carcinoma using combined reflectance confocal microscopy-optical coherence tomography: A prospective study

Abstract

Background: Initial biopsy of basal cell carcinoma (BCC) may fail to show aggressive histologic subtypes. Additionality, the clinical evaluation of BCC before surgery can miss subclinical extension. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) are emerging tools that can help in the presurgical evaluation of BCCs.

Objective: To assess the feasibility of a combined RCM-OCT imaging modality for presurgical evaluation of biopsy-proven BCCs for residual tumor, margin status, and depth.

Methods: Thirty-eight BCCs in 35 patients referred to a tertiary cancer center for Mohs micrographic surgery (MMS) were imaged with combined RCM-OCT. Images were correlated to MMS frozen sections.

Results: Thirty-eight BCCs were analyzed. The mean age of patients was 67.34 years (range, 36-84 years), and 20 patients were female (57.14%). Twenty four BCCs were located on the head (63.16%) , and the mean size was 8.58 mm (range, 3-30 mm). RCM-OCT showed an overall agreement of 91.1% with MMS frozen sections. A sensitivity of 82.6% (95% confidence interval [CI], 69%-92%), specificity of 93.8% (95% CI, 88%-97%), and receiver operating characteristic curve of 0.88 (95% CI, 0.82-0.94) was found. OCT depth was highly correlated with MMS depth (r² = 0.9).

Limitations: Small sample size and difficulty evaluating certain challenging anatomic sites.

Conclusions: Combined RCM-OCT may emerge as a useful tool for presurgical evaluation of BCCs.

Keywords: Mohs; basal cell carcinoma; biopsy; margins; optical coherence tomography; reflectance confocal microscopy; residual; surgery.

Figure 1.

A. Biopsy-proven basal cell carcinoma. A paper ring is placed around the surgical margin as determined by the Mohs surgeon. There are notches at each quadrant of the paper ring. The dashed red circle in the center represents the 1^st data point that is imaged to assess for the presence of residual BCC. The dashed red square shows an RCM image of the notch at 12 o’clock. Black arrows represent the quadrants to be imaged: 12–3, 3–6, 6–9, 9–12 o’clock respectively. Each quadrant represents an individual data point that is compared to the corresponding Mohs frozen section. B. Simultaneous co-registration of both RCM and OCT in real-time

Figure 2.

Concordance between histologic depth and OCT depth. Lin’s concordance correlation coefficient = 0.9. Pearson’s correlation coefficient = 0.9 Average difference between histologic depth and OCT depth, −21.11

Figure 3:

Superficial basal cell carcinoma (BCC) on the cheek with no clinical evidence of residual tumor. A. Clinical appearance of the biopsy site (red arrow). B. Reflectance confocal microscopy showing tumor islands (yellow asterisk) with palisading and clefting (750 × 750 μm). C. Optical coherence tomography image showing hyporeflective tumor island with retraction space (yellow arrow) measuring 200 μm in depth (1000 × 2000 μm) D. Mohs frozen section showing corresponding superficial BCC (yellow arrow), 200 μm depth. (H&E, 4X magnification).

Figure 4:

Basal cell carcinoma (BCC) on the forehead, read as ‘superficial BCC’ on biopsy report with no clinical evidence of residual tumor. A. Clinical appearance of the biopsy site (red arrow). B. Reflectance confocal microscopy (RCM) showing no evidence of residual tumor (750 × 750 μm) C. Optical coherence tomography (OCT) showing Hypo-reflective tumor cords surrounded by hyper-reflective collagen strands (yellow arrows). D. Mohs frozen section showing infiltrative BCC (H&E, 4X magnification). In this case, RCM did not show any evidence of residual BCC, but OCT suggested an infiltrative component. This case highlights the synergist value of the combined RCM-OCT device.