Evaluation of Subclinical Extension of Basal Cell Carcinoma.

Background: Basal cell carcinoma (BCC) is the most common malignancy with increasing incidence worldwide. The tumor invades surrounding tissues in an irregular pattern via subclinical and microscopic finger-like growths known as subclinical extension. Subclinical extension may be responsible for incomplete resection of the tumor. This study investigates the subclinical extension of BCC.

Methods: In a retrospective study for evaluation of subclinical extension of BCC, Patients' demographic data and characteristics (disease duration, location, size, and history of radiotherapy) were documented. Pathology samples were assessed in terms of histological type, subclinical extension, depth, and involvement of margins.

Results: The study was conducted on 102 pathological samples of 84 patients (49 males, 35 females) with BCC. The mean age was 65.4±12.55 years. Overall, 83% of pathology samples had subclinical extension. Subclinical extension had no correlation with lesion size (=0.591; r=0.056), but had a direct correlation with lesion depth (=0.033; r=0.220). Resection of the tumor with a margin of 5.5 mm eliminated the entire lesion and its subclinical extension area with a confidence rate of 95%.

Conclusion: Based on this study, resection of BCC lesions with a margin of 5.5 mm will eradicate the whole lesion including the subclinical extension area with 95% confidence rate. Depth of the tumor, not its size or histologic subtype, affects the required margin of excision.