High-frequency ultrasound in the diagnosis of selected non-melanoma skin nodular lesions

Abstract

Introduction: Ultrasonographic examination is commonly used in an outpatient setting, possibly due to its low cost, low risk for patients and the possibility to obtain real time images. Typically used heads have the frequency ranging from 7.5 to 12 MHz. Higher frequencies ensure higher resolution, yet they are limited by the penetration depth - reaching from several to several tens of millimetres into the skin. High-frequency ultrasonography (HFUS) appears to be a promising method for the detection and differential diagnostics of selected nodular skin lesions.

Aim: The study aimed at a comparison of the data obtained by using HFUS, histopathological and dermatoscopic images of selected skin lesions to determine their common features.

Material and methods: Nodular lesions classified as potentially malignant were subjected to clinical, dermatoscopic and high-frequency ultrasonographic examinations. Then the patients were referred for surgical removal with histopathological assessment.

Results: A total of 54 nodular lesions were examined, out of which 34 were diagnosed as non-melanoma. The most common lesions were melanocytic naevi dermatofibroma, nodular basal cell carcinoma and pyogenic granuloma. Other examined lesions included blue naevus, seborrheic wart, xanthogranuloma juvenile and Spits naevus. In all lesions except Spitz naevus, HFUS images corresponded at least with dermatoscopic or histopathology images.

Conclusions: HFUS can be used as a supporting diagnostic tool ensuring better pre-operative proceedings. HFUS is a non-invasive, easy and inexpensive screening method for the determination of different skin cancers as it provides valuable information allowing to determine the cutting margins and lesion shape.

Keywords: basal cell carcinoma; blue nevus; high-frequency ultrasonography; pyogenic granuloma; seborrheic wart; xanthogranuloma juvenile.

Figure 1

A – Basal cell nodular carcinoma: 1) dermoscopy: singular, irregular branched and arborizing vessels (black triangle), grey-blue dots (white dotted arrow) and globules (white triangle), 2) histopathology: compartments of individual cell groups and radiant bands between them (black arrows), 3) ultrasonography: chaotically distributed areas with intensified echogenicity (white arrows). B – Blue naevus: 1) dermoscopy, 2) histopathology, 3) ultrasonography. Pigment located superficial (black dot), pigment located in deeper areas of the dermis (black triangle). C – Seborrheic wart: 1) dermoscopy: milia-like cysts (black arrow), 2) histopathology: round intralesional cysts of loose keratin (black arrow), 3) ultrasonography: hyperechoic strands (white arrow). D – Xanthogranuloma juvenile: 1) dermoscopy: white hyperkeratotic areas (black arrow), structureless light yellow and brown areas (black triangles), 2) clinical image, 3) ultrasonography: the thickest part of the entry echo in the centre (single white arrow), thin entry echo on the edges (two white arrows). E – Spitz naevus: 1) dermoscopy: dark brown/black areas (white triangles), structureless blue/red/white areas (white arrow), 2) clinical image, 3) 50 MHz ultrasonography: clearly hypoechoic conical structure (white star), wide basis (two white stars), 4) 20 MHz ultrasonography. F – Dermatofibroma: 1) dermoscopy: network with thin lines (black arrow), shades of grey and white (black triangle), 2) histopathology: poorly defined proliferation of “fibrohistiocytic” cells within the dermis, 3) 50 MHz ultrasonography: poorly marked intradermal hypoechogenic area, 4) 20 MHz ultrasonography. G – Compound naevus: 1) dermoscopy, 2) histopathology, 3) 50 MHz ultrasonography, 4) 20 MHz ultrasonography. Pigment located in the upper layers of the dermis (black dot), pigment located in the deeper layer of the dermis (black square), parts of hair follicle (white arrow). H – Pyogenic granuloma: 1) dermoscopy, 2) histopathology: thick layer of epidermis on the surface of the lesion (black triangle), blood clots (black arrow), 3) 50 MHz ultrasonography, 4) 20 MHz ultrasonography: thick central hyperechogenic entry area (white triangle), blood clots visible in the HFUS as minor hyperechoic foci inside the nodule (white arrow)