Ultrasound Evaluation of Pediatric Orthopaedic Patients

Jody Litrenta, MD; Karim Masrouha, MD; Amy Wasterlain, MD; Pablo Castaneda, MD


J Am Acad Orthop Surg. 2020;28(16):e696-e705. 

In This Article

Soft-tissue Masses

The appearance of a soft-tissue mass is a concern that often prompts referral to pediatric orthopaedics. Often, a relatively short differential diagnosis can be made based on history and physical examination. Common causes of soft-tissue masses include ganglion cyst, popliteus cyst, abscess, giant cell of tendon sheath, foreign body, and hemangioma. Ultrasonography images can aid the orthopaedic surgeon to determine the size and composition of a mass and its position in relation to nearby structures such as joints or vasculature.[26] Grayscale images help determine echogenicity as compared to surrounding normal tissue and the architecture of the mass, whereas color doppler can show any vascularity within the mass. In addition, compressibility of the mass can aid in the differentiation of a vascular malformation or hemangioma from a solid, otherwise noncompressible mass (Figures 9 and 10). These characteristics can help the surgeon refine the differential diagnosis and determine the appropriate course of treatment.

Figure 9.

Figure demonstrating common cystic soft-tissue masses.

Figure 10.

Figure demonstrating vascularity within a soft-tissue mass.

Although ultrasonography can be useful in the workup and management of many soft-tissue masses, it is probably most definitive as a diagnostic tool in confirming cystic masses and those associated with foreign bodies. A study by AbiEzzi and Miller[26] which evaluated soft-tissue masses in 44 pediatric patients found that ultrasonography alone was diagnostic in 11/13 cystic masses and 12/18 solid masses and helpful but not diagnostic in 12/13 mixed masses. The cystic masses identified were either ganglion or popliteus cysts. The two cystic masses that were not correctly diagnosed were found to be hemangiomas on surgical exploration. Of the 12 solid masses for which ultrasonography was diagnostic, all were foreign bodies. This study corroborates another earlier study and highlights a role for ultrasonography in aiding or confirming the diagnosis in some very common pediatric soft-tissue masses with a low rate of inaccurate information.[26,27]

Both cystic masses, either ganglion or popliteus cysts, and foreign bodies are often easily identifiable by history and clinical examination alone. However, the use of a bedside ultrasonography provides objective diagnostic information. For cystic masses, sonographic data can also be particularly reassuring for those presenting in less common areas. In children, the history may be unreliable in the cases of retained foreign bodies. Ultrasonography is an excellent tool in these instances to confirm and localize the object.

Among solid or mixed masses, the role and usefulness of ultrasonography varies. In the case of giant cell tumors of tendon sheath, ultrasonography can be definitively diagnostic.[28] Fibrous tumors or hemangiomas can be more challenging to identify. Although rare in the pediatric patient, soft-tissue sarcomas are possible. Any mass not easily identifiable by sonographic findings, or accompanied by any concerning physical examination findings and/or history, should be fully evaluated with advanced cross-sectional imaging.