The plain radiographs are characterized by osseous resorption. Subperiosteal resorption of cortical bone is virtually pathognomonic of hyperparathyroidism. This is most commonly identified along the radial aspect of the middle phalanges of the second and third digit. Additional regions where subperisoteal resorption may be identified include the phalangeal tufts as well as the tibia, humerus and femur. In addition to the characteristic subperiosteal bone resorption, there may be endosteal, subchondral, subphyseal, trabecular, and subligamentous osseous resorption.
Brown tumors appear as single or multiple well marginated lesions often located within the hands.
The lesions are often eccentric and cortical in location. Other common sites of involvement include the facial bones, pelvis, ribs, and femora. Although the radiographic manifestation of a lytic lesion located within the phalanges is a somewhat nonspecific finding in which enchondroma would be in the differential, other manifestations of hyperparathyroidism are often apparent. Brown tumors are rarely associated with complications, but may on occasion result in spinal cord compression secondary to vertebral body collapse or pathologic fracture. Resnick D. Diagnosis of Bone and Joint Disorders , 2nd Edition.