Shinichi Fukuhara, Tamaki Oohashi, Hidetoshi Matsuo, Tomohiro Sameshima

BACKGROUND AND AIM

Although sternal fractures are uncommon in children. Plain radiography may be unsuitable in these cases, with the potential for missed diagnosis of a fracture and of a subcutaneous abscess.

Ultrasound examination can improve the diagnosis with demonstrated usefulness for the diagnosis of fractures including those of the sternum, in adults and children.

However, the use of ultrasound to diagnose and guide the clinical management of sternal fracture complicated by a subcutaneous abscess has not previously been reported.

METHODS

The evaluation of bone with ultrasound is performed using a high-frequency probe, with continuous evaluation of the cortex of the bone in the area of interest, with bilateral comparison.

For long bones, disruption of the echogenic cortical line is indicative of a fracture on ultrasound images. The echogenicity of an abscess, relative to surrounding structures, can also range from being anechoic to being hyperechoic.

Occasionally, the contents of the abscess are hyperechoic or isoechoic compared to the adjacent inflamed tissues, with the abscess being distinguished from cellulitis by the presence of liquefaction.

RESULTS

A 5-year-old boy presented to our ED complaining of an exacerbation of precordial pain.

The pain was associated with mild swelling over the sternum, due to an injury sustained 6 days prior when he was hit by a door.

A chest CT performed at the time of the injury did not reveal a fracture and the patient was discharged from the ED.

However, the pain and mild swelling remained constant over the next few days, and then progressed, with the swelling extending to the anterior chest, bilaterally, and the patient developing a low-grade fever. This exacerbation prompted his parents to seek further medical consultation.

On arrival to the ED, the patient was alert and cooperative, with a T 37.6°C, pulse 105 and O2 sat 98% at room air. He was in mild distress.

On physical exam, breath sounds were heard bilaterally, with no acute cardiopulmonary issues identified. Swelling was observed over the sternum, extending to the anterior chest, bilaterally. There was no observed redness in the region. The anterior chest was tender on palpation. However, direct palpation of the sternum was not possible due to the swelling.

POCUS revealed a sternal fracture accompanied by a discontinuity of the sternal alignment and fluid retention around the fracture site.

Swirling of purulent material inside the abscess was observed by movement of the point of high echogenicity. The swelling over the anterior chest was diagnosed as subcutaneous fluid retention.

A contrast chest CT examination was performed, revealing a sternal fracture with a subcutaneous abscess.

CONCLUSION

In this case, we demonstrate its usefulness for the diagnosis and appropriate management of a sternal fracture, complicated by a subcutaneous abscess, in a young child, that was not previously detectable on chest CT.

As POCUS can be easily performed at the bedside, its use would be warranted to rule out a sternal fracture in pediatric patients presenting with swelling of the anterior chest and local tenderness of the sternum, even if these fractures are deemed to be uncommon in children.

Our case further demonstrates that POCUS can be useful for detecting a subcutaneous abscess complicating the sternal fracture, allowing us to provide appropriate treatment.