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Background
Superficial soft-tissue masses are cutaneous or subcutaneous in location in comparison to deeper soft-tissues masses, which usually require further imaging. Superficial lesions have a variety of diagnoses ranging from benign lesions to pathologies that require biopsy or surgical consultation. Ultrasonography can reliably characterize superficial soft-tissue masses and be used to provide recommendations to ordering physicians.

Educational Goals / Teaching Points
Superficial soft-tissue masses commonly lead to pain, edema, or other symptoms. Superficial soft-tissue masses may be characterized as benign masses, pseudomasses, enlarged lymph nodes, or neoplastic processes. Accurate identification of these masses is necessary to guide further management. Ultrasonography can sufficiently characterize superficial masses and allow for diagnosis of the most common entities. Radiologists should be comfortable describing and diagnosing common superficial soft-tissue masses.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Benign masses include lipomas, fat necrosis, epidermal inclusion cysts, sebaceous cysts, peripheral nerve sheath tumors (PNST), vascular malformations, ganglia, nodular fasciitis, and subcutaneous endometriosis. Lipomas present as hyperechoic or isoechoic masses with linear hyperechogenic strands and minimal vascularity. Fat necrosis presents with mixed echogenicity, poor margins or a hypoechoic halo, and no vascularity. Epidermal inclusion cysts present as hypoechoic masses with anechoic or hypoechoic keratin debris, no vascularity, and possible tracts to the epidermis. PNSTs present as hypoechoic, well-circumscribed masses with nerve continuity and internal vascularity. Vascular malformations present as heterogeneous masses with hypoechoic and hyperechoic components and vascular flow. Ganglia are mucinous hypoechoic or anechoic masses usually without vascularity. Nodular fasciitis refers to a hypoechoic or isoechoic nodule with mild vascularity. Subcutaneous endometriosis presents as heterogeneous, hypoechoic lesions with hyperechoic components with or without vascularity. Pseudomasses include bursa, abscess, foreign bodies, and hematomas. Bursitis presents as a hypoechoic sac with possible internal echogenicity and variable vascularity. Abscesses present as hypoechoic heterogeneous masses with internal echoes and peripherally increased vascularity. Foreign bodies have variable presentation, but may be echogenic with posterior shadowing, and possible peripheral hypoechogenicity and vascular flow. Hematomas present as avascular hypoechoic areas with variable internal echogenicity. Lymph nodes present as hypoechoic ovals with hyperechoic hila and internal vascular flow. Enlargement may be reactive or due to lymphoma, leukemia, or metastasis. Neoplastic processes may present with nonspecific findings including a hypoechoic solid or mixed solid and cystic appearance with heterogeneity and internal vascular flow.

Conclusion
Common superficial soft-tissue masses can be diagnosed with ultrasonography. Accurate characterization, diagnosis, and recommendations from radiologists are necessary to ensure appropriate management.