Hand and Forearm Tc-99m HMDP Bone Image Findings of Reflex Sympathetic Dystrophy Similar to Those of Radiopharmaceutical Arterial Administration in the Arm

A patient with a four year history of right shoulder pain was referred for a bone scan. His chest CT scan showed a calcified mass lesion in the posterior aspect of the right lung, involving the right fourth rib posteriorly. The Tc-99m HMDP showed diffuse uptake in the soft tissue of the right forearm and the right hand, as well as the elbow, wrist, proximal half of the right ulnar, and two-thirds of the right radius and bones of the hands, consistent with reflex sympathetic dystrophy (RSD). These findings are almost identical to those of the patient who received arterial administration of the bone-imaging agent into a brachial artery. In the RSD patient, the shoulder pain probably related to erosion of the fourth rib by the tumor mass. This may produce neurovascular flush—vascular dilatation and permeability—and sympathetic nervous system effect on the microcirculation within the bone and joint to open closed vessels. The end result would be identical to those effects in brachial arterial administration, to allow more radiopharmaceutical uptake in the bones and joints distal to the elbow.