Working Diagnosis:
Scalene Muscle Strain with hematoma/seroma formation

Treatment:
Watchful waiting was recommended with close follow up including weekly measurements both manually and with ultrasound. Furthermore, the patient was instructed to avoid activities that could lead to contact with the afflicted area or require extensive use of the arm, shoulder or neck.

Outcome:
Upon return visit 2 week later, the fullness in the right supraclavicular fossa had decreased significantly with associated improvement in the tightness described with neck movements.

Author's Comments:
Participants in organized sports are on the rise with an estimated 30-45 million children playing annually. Despite the numerous benefits of athletics, participants are at an increased risk for injury. Factors such as maturational status, body mass index (BMI), gender, anatomic variation and biomechanical movement patterns are intrinsic predispositions to injury. Muscular injury can be broadly classified as extrinsic, including contusions and penetrating wounds corresponding to a site of impact, or intrinsic injuries caused by contraction and concurrent elongation of muscle leading to fiber destruction at the myotendinous junction. Intrinsic injury, also known as strain, can be further categorized as grade 1 through 3 wherein grade 1 is microscopic tear, grade 2 is discontinuity of muscle fiber with hypervascularity and grade 3 is complete discontinuity of muscle fibers often with retraction of tendon ends. Moreover, hematoma formation can commonly be seen with grade 2 strain and can be pathognomonic for such an injury. Muscle hematoma typically resolves in 6 to 8 weeks, however, once blood products have resorbed, a seroma may develop and persist. Finally, under the appropriate clinical context, it is important to remember that the intramuscular hematoma mass-like appearance on MR imaging must be differentiated from a hemorrhagic tumor, particularly one with central necrosis.

Editor's Comments:
Supraclavicular masses are typically thought of as concerning for metastatic lesions from the pulmonary, gynecologic or gastrointestinal systems. Imaging evaluation can be performed with ultrasound, CT or MRI (as in this case). CT and MRI provide greater information than ultrasound in that they are able to better characterize the mass. MRI provides better soft tissue differentiation than CT. In this case it was not only able to identify the mass but also demonstrate the mass origin (scalene strain).

References:
Blankenbaker, DG.; Tuite, MJ. Temporal changes of muscle injury. Semin Musculoskelet Radiol. 2010 June: 14(2):176-93

Draghi, F.’ Zacchino, M.; Canepari, M.; Nucci, P.; Alessandrino, F. Muscle injuries: ultrasound evaluation in the acute phase. J Ultrasound. 2013 May: 16(4)209-14

Paterno, MV.; Taylor-Hass, JA.; Myer, GD.; Hewett, TE. Prevention of overuse sports injuries in the young athlete. Orthop Clin North Am. 2013 Oct: 44(4)533-64

Shelly, MJ.; Hodnett, PA.; MacMahon, PJ.; Moynagh, MR.; Kavanagh, EC.; Eustace, SJ. MR imaging of muscle injury. Magn Reson Imaging Clin N Am. 2009 Nov: 17(4)757-73

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