Unicameral
bone cysts (UBCs) in children usually are asymptomatic. Most UBCs are discovered when a radiograph is performed on a child who has had accidental
trauma to a limb. Symptomatic
cysts typically present with
pain, often the result of
pathologic fracture through a large
cyst or occult
stress fracture within the thinned cortex around the
cyst. Simple radiography is the best method for detecting such
cysts, which typically are located within the long bone (femur, tibia, fibula, humerus), but can appear elsewhere.
Cysts typically appear in the proximal metaphysis, but some involve the epiphysis and growth plate, thereby affecting bone growth. If clinically necessary to confirm the diagnosis, computed tomography or magnetic resonance imaging can delineate the
cyst better or demonstrate an
occult fracture. For the asymptomatic UBC, close follow-up is the recommended course of action. However, surgical intervention by
corticosteroid or autogenous bone marrow injection or open
curettage with
bone grafting is recommended if the
cyst is symptomatic, carries an increased risk for
pathologic fracture (weight-bearing bone or dominant arm of a throwing athlete), or shows signs of an impending
pathologic fracture. Clinical and radiographic follow-up is recommended after surgical intervention, because UBC recurrence after initial surgery is reported to occur in 18% to 88% of patients.