Quick detection of nonmelanoma skin cancer by histopathology: feasibility and diagnostic accuracy of immediate cutaneous diagnosis

Background: Dermoscopy, diagnostic cytology, confocal microscopy are used to improve diagnostic accuracy. Frozen section techniques have been used to control margins but not for diagnosis. Objectives: We used a new frozen section technique called immediate cutaneous diagnosis for nonmelanoma skin cancer, assessing its feasibility and accuracy in obtaining a result within 15 minutes and recording limitations. Methods and Materials: An observational, prospective clinical study was designed. Biological samples were divided into two: one half was included in paraffin, following the standard procedure, and immediate cutaneous diagnosis was applied in the other. Fresh tissue was examined by frozen sections with perpendicular slides and staining with toluidine blue. Two hundred and sixty patients were enrolled. Results: Immediate cutaneous diagnosis-toluidine blue had a sensitivity of 98.7% (95%CI: 93.0-100%) and a specificity of 92.6% (95%CI: 87.4-96.1%) in detecting nonmelanoma skin cancer. Inter-rater agreement between two dermatopathologists using Cohen's kappa was 0.796 (P<0.0001) in a subsample of 101 cases. Immediate cutaneous diagnosis-toluidine blue had a sensitivity for squamous epithelial lesions of 78.3% (95%CI: 63.689.1%) and a specificity of 98.4% (95%CI: 95.5-99.7%)

Challenges for New Adopters in Pre-Surgical Margin Assessment by Handheld Reflectance Confocal Microscope of Basal Cell Carcinoma; A Prospective Single-center Study

In vivo reflectance confocal microscopy (RCM) is a useful tool for assessing pre-surgical skin tumor margins when performed by a skilled, experienced user. The technique, however, poses significant challenges to novice users, particularly when a handheld RCM (HRCM) device is used. To evaluate the performance of an HRCM device operated by a novice user to delineate basal cell carcinoma (BCC) margins before Mohs micrographic surgery (MMS). Prospective study of 17 consecutive patients with a BCC in a high-risk facial area (the H zone) in whom tumor margins were assessed by HRCM and dermoscopy before MMS. Predicted surgical defect areas (cm 2) were calculated using standardized photographic digital documentation and compared to final defect areas after staged excision. No significant differences were observed between median HRCM-predicted and observed surgical defect areas (2.95 cm 2 [range: 0.83-17.52] versus 2.52 cm 2 [range 0.71-14.42]; P = 0.586). Dermoscopy, by contrast, produced significantly underestimated values (median area of 1.34 cm 2 [0.41-4.64] versus 2.52 cm 2 [range 0.71-14.42]; P < 0.001). Confounders leading to poor agreement between predicted and observed areas were previous treatment (N = 5), a purely infiltrative subtype (N = 1), and abundant sebaceous hyperplasia (N = 1). Even in the hands of a novice user, HRCM is more accurate than dermoscopy for delineating lateral BCCs margins in high-risk areas and performs well at predicting final surgical defects