Ultrasonography is routinely used for the evaluation of skin and soft tissue complaints. It is relatively easy to perform due to the superficial location of each structure allowing for high-frequency imaging, thereby producing high-resolution, detailed images. Commonly, ultrasound is used to evaluate for abscess, cellulitis, and foreign bodies within the skin and soft tissue. Recently, evidence demonstrates that ultrasound is becoming more useful and efficient in the diagnosis of necrotizing fasciitis, a life-threatening condition that requires timely recognition. This chapter will review basic skin and soft tissue anatomy, image acquisition, normal ultrasound anatomy, and interpretation of pathology.
KeywordsCellulitis Abscess Hematoma Necrotizing fasciitis Foreign body Lymph node
Normal skin and soft tissue ultrasound. Soft tissue layers from superficial to deep include: epidermis, dermis, subcutaneous tissue (hypodermis), fascia, muscle, bone (MP4 629 kb)
Cellulitis. Cellulitis typically appears as cobblestoning of the subcutaneous tissue with associated thickening of the dermal layers (MP4 2251 kb)
Cellulitis with increased tissue edema. Note cobblestoning with increased anechoic areas due to severe cellulitis and/or concomitant tissue edema of other etiology (MP4 2160 kb)
Abscess. Hypoechoic fluid collection with internal echogenic debris representing an abscess (MP4 2040 kb)
Abscess with internal swirling from compression. With compression by the transducer, internal swirling of abscess contents will occur. This can help distinguish an abscess from other etiologies such as a lymph node (MP4 2024 kb)
Necrotizing fasciitis with perifascial fluid. Fluid tracking along the fascial plane with thickened subcutaneous tissue and a loss of normal architecture. Perifascial fluid greater than 4 mm likely indicates a diagnosis of necrotizing fasciitis (MP4 2279 kb)
Hematoma. Hypoechoic fluid collection representing abdominal hematoma. On ultrasound, may be indistinguishable from abscess (MP4 473 kb)
Metal foreign body in long axis. Brightly echogenic foreign body represents a broken needle within the neck of a patient from intravenous drug abuse (MP4 1940 kb)
Metal foreign body in short axis. Brightly echogenic foreign body represents a broken needle within the neck of a patient from intravenous drug abuse (MP4 2110 kb)
Lymph node. Lymph node with hyperechoic medulla surrounded by hypoechoic cortex. Also imaged are two vascular structures that are more round and anechoic when compared with a lymph node (MP4 2174 kb)
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