Renal osteodystrophy - metabolic superscan

Case contributed by Dr Evan Sirc

Patient Data

Gender: Male

Tc-99m MDP bone scan

Nuclear medicine

Anterior and posterior planar images from a Tc-99m MDP whole body bone scan demonstrate diffusely increased radiotracer uptake throughout the axial and appendicular skeleton. Especially intense activity is noted in the mandible and maxilla. There is absent renal and bladder activity.  

Lateral radiograph of the skull demonstrates numerous small lucent foci throughout the calvarium creating a "salt and pepper" appearance.  

AP radiograph of the pelvis demonstrates diffuse osteosclerosis.  A partially calcified transplant kidney is incidentally noted in the right pelvis. 

Lateral radiograph of the lumbar spine demonstrates osteopenia with a biconcave appearance of some vertebral bodies ("fish vertebra" appearance).  

Case Discussion

The appearance of the bone scan is consistent with a "metabolic superscan," in this case due to secondary hyperparathyroidism (renal osteodystrophy).  Note that activity is increased throughout the entire skeleton, including the distal appendicular skeleton, which is characteristic of a superscan due to metabolic disorders.  In contradistinction, a metastatic superscan will typically affect only the axial and proximal appendicular skeleton.  Another differential consideration for this case would include multifocal Paget disease, although the appearance would typically not be so uniform.  

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