CASE 9
By: Dr. Saleh Othman, MD, MSc, JMCB
HISTORY: A 54-year-old male patient with chronic renal impairment presented with progressive muscle and bony pain. Laboratory data showed elevated parathyroid hormone and high value of corrected calcium.
What are your findings?
What is you’re your differential diagnosis?
What is the value of bone scan in similar disease conditions?
FINDINGS:
Generalized increased tracer uptake throughout whole the skeleton with no soft tissue uptake (Super scan). Note the bilateral lung and stomach uptake due to known hypercalcemia. Findings suggestive of hyperparathyroidism.
DIFFERENTIAL DIAGNOSIS:
Other metabolic bone disease such as osteomalacia, osteoporosis, Paget’s disease, fibrous dysplasia, osteopetrosis.
DIAGNOSIS:
Hyperparathyroidism.
PEARLS AND DISCUSSION:
Hyperparathyroidism(HPT) is of three types. Primary HPT caused by hyperplasia or adenoma of parathyroid glands and secondary HPT which is usually associated with chronic renal failure. 50-80% of patients with primary HPT have normal bone scan unlike secondary HPT which is usually have abnormal bone scan.
Bone scan in other metabolic bone disease: It has a limited value:
Osteomalacia: Is a metabolic bone disease caused by vitamin deficiency which leads to failure of the bone matrix to calcify. Bone scan usually shows generalized increased uptake and sometime show pseudo fractures which appear as focal areas of increased uptake.
Osteoporosis: Bone scan usually normal. If there are any fractures (insufficiency fractures), it will appear as focal increased uptake at the fracture site.
Paget’s disease: Bone scan shows diffuse increased uptake in involved bones. The disease usually polyostotic but in 20% of cases can be monostatic. If changes occur in bone scan over a brief period of time, they should not be attributed to Paget’s disease, and other pathology (e.g. metastases) should be considered.
Fibrous dysplasia: Bone scan shows increased uptake in affected bones. Lesions in polyostotic fibrous dysplasia are often unilateral (Albright Syndrome) they may be bilateral.
Teaching points:
The diagnosis of hyperparathyroidism is based on biochemical markers, and bone scanning has a limited role in making the diagnosis.
Bone scanning may assist in differentiating hyperparathyroidism from metastatic disease in the setting of elevated calcium levels. In HPT, findings a super bone scans include generalized increased uptake throughout the skeleton including appendicular bones and no soft while in metastatic super scan appendicular bones are spared.
Osteomalacia is a laboratory diagnosis and bone scan add little information to the diagnosis, but it may reveal pseudofractures which may explain some of the patient symptoms.
FURTHER READING:
Bone Scintigraphy: Part 3. Bone Scanning in Metabolic Bone Disease. I. Fogelman, B.D. Coffier and M.L. Brown. J Nuci Med 1993; 34:2247-2252
Bone scan in metabolic bone diseases. Review. Saeid Abdelrazek, Piotr Szumowski, Franciszek Rogowski, Agnieszka Kociura-Sawicka, Małgorzata Mojsak, Małgorzata Szorc Nucl. Med. Rev 2012;15(2):124-131.
