Periosteal chondroma of the hand and humerus

A) Hand – Observe the juxtacortical radiolucency present within the metaphysis of the proximal phalanx (arrow). There is a cortical indentation, with scalloping or a saucerized depression of the outer cortex and a well-defined inner margin.
B) Humerus – Note the rather large cortical indentation with scalloped inner margins present on the medial aspect of the metaphysis of the proximal humerus. The classic cortical saucerized depression at the outer cortex, with a well-defined inner margin, is visualized at the caudal aspect of this lesion. This is a characteristic appearance for a periosteal chondroma (juxtacortical chondroma).