Question:My grandson is 9 years old very petite for his age, He is really tiny. He broke his arm (humerus) while throwing the basketball at the basket. It turns out he has aggressive Unicameral bone cyst. They will do a biopsy next week. My question is what is the proper treatment for this tumor? The tumor is very large compared to his bones and I believe it may be in his growth plate. Thank you so much for your help!
Answer:A unicameral bone cyst is a benign lesion. It can cause problems because instead of bone structure, there is a hole filled with fluid, so these kids do tend to break with a small amount of energy. If the cyst touches the growth plate – it is active and may be getting bigger. Once the bone decides to behave and on x-ray that cyst moves away from the growth plate (meaning the growth plate grows and starts making bone instead of a hole) then it is a latent cyst. These cysts are painless and asymptomatic. They are most commonly found incidentally when the child has an x-ray for another reason, or, in your case, because a small trauma caused the bone to break through the cyst.
There are several ways that the bone cyst may go away. The inflammatory response from the fracture may cause the bone cyst to heal (by not typically) More aggressively – your Orthopedic Surgeon may offer Steroid injections into the cyst (this too is not a guarantee and may take several injections) he or she may offer curettage and bone grafting (that means the cyst gets scraped out and filled with some sort of bone graft) The cyst may return after even that. Your surgeon may suggest spanning the cyst with intramedullary nails (they look like knitting needles and they go inside the bone.) That technique affords some protection from future fracture and in and of itself may allow the bone cyst to heal.
Ultimately – when your grandchild’s growing bone is no longer using all the energy to grow (age ~16 for boys and ~14 for girls) the bone will begin remodeling (I think of this like paving the highway; old bone is eaten up and new bone is laid down) Shortly after that – this cyst will disappear.
The x-ray features of a unicameral bone cyst are classic and it is unlikely something else. The treatment your family choses depends on the sports your grandchild plays and how much growth he has remaining.