Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to benign etiology. In fact, although the appearance of the corticomedullary junction of bones affected with myeloma and metastases can look very similar (and the term endosteal scalloping is used by many authors) the underlying mechanism of resorption may well be different .
Lesions that typically result in endosteal scalloping include: