Simple Bone Cyst

Simple bone cyst is a benign (non-cancerous) indolent tumor of bone. It’s commonly seen in very young kids. Most commonly it involves Humerus (arm bone). However, it can affect any bone of body. It is basically an area of bone where the normal calcium deposition has not occurred and a cavity filled with fluid has persisted. This makes that part of bone weak and it can fracture even with minor trauma. This remains the commonest presentation scenario for SBC. In some kids, it is presented as an incidental finding where an x-ray is done for pain due to some other cause and this lesion is revealed.

Exact cause of Simple bone cyst is unknown. However, it has been linked to genetic mutations and also calcium metabolism disturbances.

It is diagnosed with the help of Xray, MRI and CT scan. It is usually a diagnosis made on clinical symptoms and xray – MRI. Biopsy is seldom needed.

Many patients present with fracture. If it’s the upper limb cyst, a simple plaster / splint immobilization is done for 6 weeks. In lower limb cyst, if patient presents with fracture, it needs fixation with nail / plate. Fracture almost always heals on its own and in over 40% of patients, even cyst heals. If the cyst remains persistent, then further treatment is done for it.

Current standard of care for treatment of SBC is known as “Curopsy”. It is a minimally invasive treatment where only a 5 mm cut is made on the skin and the cyst walls are removed with a special needle. In the same sitting, steroid injection is made in the cyst. This procedure may need to be repeated 2 or 3 times at 6 to 8 weekly interval. Success rate of this procedure is 80%.

As far as possible, a major surgery is avoided in treatment of SBCs. But in resistant cysts, intralesional curettage is done which is curative in almost all the patients.

Once the treatment is over, patient needs to follow up on regular bases irrespective of any problems for next 5 years. It is only then, that the patient is declared free of tumor!