Aim: While histology remains the "gold standard" for cutaneous tumoral pathology, high-frequency ultrasound (HFUS) was shown to play a significant role in the non-invasive, pre-therapeutic assessment of skin tumors. The aim of our study was to determine whether there is a significant correlation between the ultrasound (US) and histological measurements of basal cell carcinoma (BCC) tumor depth. Materials and Methods: The present study retrospectively analyzed clinical, dermoscopy, HFUS and histological examinations of 90 patients (52 men and 38 women) with histologically confirmed BCC, with focus on tumor depth index (DI). Results: On clinical examination, 54 lesions were nodular (32 presented ulcerations) and 36 superficial lesions. Dermoscopy showed suggestive signs of BCC, most frequently "in focus" arborising superficial vessels (n=81), blue-grey ovoid nests (n=48) and specks of brown pigment (n=7). HFUS revealed well-defined (n=88) or poorly defined (n=2) hypoechoic, vascularized lesions, with inhomogeneous structure (n=90) and characteristic hyperechoic dots (n=36). A strong correlation (Pearson's r=0.92) between the HFUS (mean measured US depth = 1.33 mm) and histological (mean measured histological depth = 1.47 mm) DI of the investigated skin lesions was found, although significant differences (p<0.001 -t-test for paired samples) between the two measurements were observed. Conclusions: HFUS provides reliable information about BCC depth of invasion that cannot be otherwise obtained prior to surgery. In this manner, it completes the preclinical evaluation and can have an impact on the choice of the optimal therapeutic method.

Basal cell carcinoma (BCC) is a malignant skin cancer which commonly exhibits aberrant blood flow because of angiogenesis. Its invasiveness and lack of metastatic potential may be explained by the typical pattern of vascularization seen in BCCs, where blood vessels are absent in the tumor islands and prominent in the tumor’s periphery. From clinical point of view, high-frequency ultrasound (HFUS) is a useful tool for the evaluation of the lateral and depth extension of these tumors; furthermore, by employing color Doppler, important data regarding the vascularization degree of BCCs is provided. Knowingly, the sonographic vascular pattern of cutaneous tumors can aid in improving diagnosis and treatment by differentiating between benign and malignant lesions, between various types of cutaneous malignancies and also between various types of BCC (e.g., low risk versus high risk). Our aim was to perform a review integrating all currently known vascular properties of BCC as a tumor entity.