Unicameral (simple) bone cyst is a common benign bone lesion frequently found in children and adolescents, typically occurring in long bones such as the humerus or femur. These cysts are characterized by a well-defined, fluid-filled cavity within the bone, usually containing clear yellowish fluid, and are often found incidentally during imaging studies conducted for other reasons, such as fractures. Generally, unicameral bone cysts are asymptomatic; however, they can lead to bone weakness and fragility, increasing the risk of pathological fractures, particularly in weight-bearing bones. The precise etiology of these cysts remains unclear, although they are believed to arise from a combination of developmental abnormalities and changes in the bone's normal remodeling process. Imaging studies, primarily X-rays, show a characteristic appearance: a lucent lesion with well-defined margins in the metaphysis of long bones. In some cases, Magnetic Resonance Imaging (MRI) may be utilized to further assess the cyst and differentiate it from other bone lesions. The treatment approach for unicameral bone cysts often depends on the size of the cyst, the symptoms presented, and the patient's age. Small, asymptomatic lesions usually require no intervention and can be monitored over time, as many cysts resolve spontaneously. However, for larger cysts or those that cause significant symptoms or instabilities, various treatment options are available. Intralesional curettage, which involves the surgical removal of the cyst, followed by filling the cavity with a bone graft or bone substitutes, is a common surgical intervention aimed at promoting bone healing. In some cases, especially when there is a high risk of fracture, corticosteroid injections can be administered directly into the cyst to reduce inflammation and encourage healing. Recurrence of the cyst after treatment is possible, and regular follow-up with imaging is recommended to monitor for any changes. Overall, while unicameral bone cysts are generally benign and can resolve naturally, proactive management may be necessary to prevent complications associated with bone fragility and to ensure optimal outcomes for affected individuals. It is crucial for healthcare providers to differentiate between unicameral bone cysts and other more serious lesions, such as aneurysmal bone cysts or malignancies, thereby necessitating careful imaging and clinical evaluation. The prognosis for patients with unicameral bone cysts is typically excellent, especially with appropriate management and monitoring, allowing individuals to continue normal activities and maintain a good quality of life.
