Investigation of Superficial Soft Tissue Lesions

Clinical Context and Diagnostic Approach

The American College of Radiology recommends ultrasound as the initial imaging modality for superficial soft tissue lesions, due to its excellent diagnostic accuracy, with a sensitivity of 94.1% and specificity of 99.7% for characterizing common superficial masses, in patients presenting with a well-demarcated, red, painful lesion on the thigh 3
Ultrasound can differentiate solid from cystic lesions, identify fluid collections requiring drainage, and characterize the lesion's relationship to adjacent structures without radiation exposure, which is particularly important for initial evaluation in elderly patients 1, 2, 3
The use of high-frequency transducers (≥10 MHz) in ultrasound detects even minor inflammatory changes and can characterize effusions, guiding further management, such as aspiration or biopsy, in patients with suspected soft tissue lesions 1, 2

The American College of Radiology suggests that imaging should precede biopsy to characterize the lesion and guide biopsy site selection, reducing the risk of inadequate sampling or complications, and recommends core needle biopsy over fine-needle aspiration for solid masses 4, 5
Ultrasound-guided aspiration is recommended for fluid collections, enabling microbiological culture and cytological analysis, which is crucial for diagnosing infections or malignancies in patients with superficial soft tissue lesions 4

The initial step in the clinical algorithm is to perform an ultrasound examination with a high-frequency transducer to characterize the lesion, which helps in identifying the need for further imaging or intervention, such as MRI or biopsy, in patients with atypical or inconclusive ultrasound findings 1, 2, 3
If ultrasound findings are atypical or inconclusive, MRI is recommended for further characterization, providing more detailed information on the lesion and its relationship to surrounding structures 3