To investigate the sonographic manifestations of skin diseases, by means of combining an ultrasound biomicroscope (UBM) with a 50 MHz probe and a conventional ultrasound machine with a wide-band high frequency probe.

From March 2013 to December 2016, 124 patients with 136 skin lesions that were proven by surgical and pathological findings were enrolled in the study. Among them, 105 patients (117 lesions) had benign and 19 patients (19 lesions) had malignant lesions. Each case was scanned with a UBM and its 50 MHz probe, and the other conventional ultrasound machine and its 6-15 MHz probe. Eleven types of sonographic manifestations were described according to pathological classifications: layers of the skin lesion, internal character, continuity of the epidermis, keratinization of the epidermis, flatness of skin surface, shape, boundary, internal echo, posterior echo, internal blood flow, and peripheral blood flow.

Sonographic features of various benign and malignant skin lesions were demonstrated. Benign lesions: Pigmented nevus: A lesion located in the epidermis and dermis, with a regular shape, a clear boundary, and no or little blood flow; Seborrheic keratosis: A lesion causing the hyperkeratosis of the epidermis, with posterior attenuation and no or little blood flow; Epidermoid cyst: A lesion located in the dermis and subcutaneous layer, with solid or complex component, posterior attenuation, and no or little blood flow; Blue nevus: A lesion confined to the dermis, with an oval or round shape, a clear boundary, and no or some blood flow; Dermatofibroma: A lesion located in the epidermis and dermis, or infrequently involving subcutaneous tissues, with a regular shape, an unclear boundary, and no or little blood flow; Hemangioma: A lesion located in the epidermis and dermis, extending into subcutaneous tissues in some cases, with solid or complex component, posterior enhancement or not, and internal hypervascular supply with few peripheral vessels; Lipoma: A lesion located subcutaneously and appearing as high echogenicity, posterior enhancement, and no internal blood flow. Malignant lesions: Basal cell carcinoma: A tumor located in the epidermis and dermis, invading into the subcutaneous layer in some cases, with interruption of skin layers, epidermal hyperkeratosis, a rough surface, an irregular shape, a clear boundary, posterior attenuation or not, and some or abundant internal blood flow; Squamous cell carcinoma: An infiltrative tumor involving the subcutaneous tissue, with marked thickening of keratinized epidermis, a rough surface, an irregular shape, a clear boundary, posterior attenuation, internal hypervascular supply, and no continuity of the epidermis; Actinic keratosis: A change limited in the epidermis and the dermis, with epidermis hyperkeratosis, an irregular shape, an unclear boundary, posterior attenuation, and intact epidermis; Bowen's disease: A tumor invading the epidermis, dermis, and subcutaneous layer, with epidermis hyperkeratosis, an irregular shape, an ill-defined margin, posterior attenuation, some internal blood flow, and complete epidermis.

Various skin lesions not only share common sonographic manifestations but also have characteristic changes. UBM combined with conventional ultrasound examination is helpful for the classification and differentiation of skin diseases, and has important application value in the diagnosis and treatment of skin diseases.