What can cause painless swelling in a baby's tibia bone?

Hi,

Welcome to icliniq.com.

It looks like your child has a painless bump on the tibia or leg. Can you describe where exactly you see this swelling or bump, either upper, mid, or lower tibia? Has this been evaluated by a doctor with X-rays? There can be numerous causes for such swelling. My most common suspicion would be bow legs which may be normal in kids of that age. Early standing is usually not correlated with any skeletal problems. But early walking has been correlated withBlount's disease (growth variant of tibia). If the swelling or bump is in the lower half of tibia, it could be a congenital pseudoarthrosis, which is pretty rare. Tumors, infection, etc., are other rare causes. I would be able to give more accurate information if you could send me some pictures of your kid's legs. If x-rays have been done, you could attach those too.

Thank you.

Hi,

Welcome back to icliniq.com.

Thank you for attaching the x-rays (attachment removed to protect patient identity) and for giving me an opportunity to assist you. From the x-ray, it looks like he has a thickening of the anterior cortex (outer shell of bone). A few reasons for this thickening are osteofibrous dysplasia (OFD) and adamantinoma. Simply anterolateral bowing of the tibia is a precursor of pseudoarthrosis. There may be other rarer possibilities too which only a biopsy may help rule out. Adamantinoma is the least likely one since it usually does not occur at such a young age. Has he been diagnosed with any particular syndrome? Have you noticed any skin patches anywhere in the body? The latter could be a sign of a condition called neurofibromatosis (NF-1). There is an association between anterolateral bowing of the tibia and pseudoarthrosis with NF-1. While a biopsy of this lesion may give us a tissue diagnosis, I would not suggest starting with that for now. The reason is, for both OFD and anterolateral bowing, the initial treatment is observation (wait and watch). If the swelling keeps on worsening, it may be prudent to do serial X-rays to see if the appearance changes. Right now, there are no cystic changes (dark cavities within the thickening) on the X-rays. If these cysts appear in the near future, it would indicate a weakening of the bone and the possibility of a fracture. If the bowing worsens, and the deformity becomes asymmetric from the other leg, he may need a brace to prevent a fracture and possible pseudoarthrosis. If no fracture occurs, he may not need any surgery till his adolescence. Even at that time, the surgery would be just to realign the deformed tibia if needed. I know this is a lot of information and can be overwhelming. I would suggest reading about congenital pseudoarthrosis of tibia over the internet, if possible, to know more about this condition. I would also strongly suggest seeing an orthopedic surgeon with expertise in pediatric orthopedic problems to evaluate this swelling. You may be advised a biopsy or other imaging studies like CT or MRI to further evaluate this swelling. If it turns out to be OFD or anterolateral bowing, there is about a 10 to 30 % chance of fracture and pseudoarthrosis in the future. I do not think being an early stander or walker has caused this problem. However, there is a chance that the deformity may worsen in him because he is at an age where the normal (physiological) bowing at the knee can stress his tibia more than usual.

Thank you.