A 12 year old with arm pain after doing push ups during gym class. What is the diagnosis?
Answer
Diagnosis: Pathologic fracture with a unicameral bone cyst
Unicameral bone cysts are benign lesions that mainly affect children and adolescents. On xray the cyst is noted to be a mildly expansile, lytic, thin walled lesion without periosteal reaction. The most common sites are the proximal humerus and femur. These lesions can resolve spontaneously, but there is a risk of pathologic fracture. If fracture is detected, then the fracture site should be treated as any other fracture in the area. These lesions can also be found incidentally in which case they should be referred to orthopedics for outpatient follow up.
References
Kadhim, M, Thacker M, Kadhim A and Holmes L. Treatment of unicameral bone cyst: systemic review and meta analysis. J Child Orthop. 2014 Mar; 8(2): 171-191.
Mascard E, Gomez-Brouchet A, Lambot K. Bone cysts: Unicameral and aneurysmal bone cyst. Orthop Traumatol Surg Res. 2015 Feb; 101.
