Ultrasound technology in dermatology.

As a noninvasive diagnostic method, real-time B-mode sonography belongs to the diagnostic standard procedures in various fields of clinical medicine, for example, internal medicine, gynecology, and otorhinolaryngology. During the past 3 decades, ultrasound technology has been extended to clinical dermatology. High-frequency ultrasound systems with 20- to 50-MHz probes are used for the assessment of tumoral and inflammatory processes of the skin, providing information about their axial and lateral extension. They are of special interest in preoperative situations and for the monitoring of skin conditions under therapy. In contrast to high-frequency ultrasound systems, the value of ultrasound technology with the use of 7.5- to 15-MHz probes generally is not accepted worldwide, although it can be used easily and without significant side effects. Promising results have been reported from specialized diagnostic centers, especially for the assessment of peripheral lymph nodes and soft-tissue tumors. Although it is unable to provide malignancy specific information, ultrasound is nonetheless helpful in the follow-up of patients undergoing, for example, chemotherapy or radiotherapy. The 3-dimensional size and outline of a tumor as well as its relation to surrounding structures like vessels can be described. Moreover, information about the tumor quality (solid, cyst, complex) and the inner structure of a tumor (hypoechoic, hyperechoic, homogenous, inhomogenous, calcification foci, necroses) can be provided. In addition to conventional B-mode-sonography, newer ultrasound techniques like native and signal-enhanced color Doppler sonography as well as ultrasound-guided fine needle aspiration cytology are reviewed.