Bone Island

Hi, I went in for x-ray of knee because of possible arthritis and as a result of x-ray they saw what they call a bone island in my tibia.  I now have to go for a bone scan because my doctor said that no doctor is willing to say the bone island is not cancer without further follow-up because of my previous cancer.  What are they looking for on a scan, can they tell the difference between a bone island and bone mets on a scan?

[Fernando Roque, MD]

Hi.  Metastatic bone lesions create three characteristic radiographic patterns, osteolytic, osteoblastic or mixed.  When bone destruction predominates and the host bone fails to react, an osteolytic pattern is seen.  When the formation of new material by the host bone predominates, an osteoblastic pattern appears.  Mixed patterns happen when neither process is dominant.  Osteolytic lesions appear moth-eaten and map-like, while osteoblastic lesions have irregular areas of thick new bone formation.  

There is no pattern that is diagnostic of a particular type of cancer, but breast cancer often presents with an osteolytic or mixed lesion.  With a bone island I would expect the lesion to be more of the osteoblastic type.  But there are always exceptions to these generalizations.