Age / Sex : 15 / M

Age / Sex :
15/M

Chief complaint : limping gait (D : 1 year)

Primary hyperparathyroidism by parathyroid adenoma

Discussion

Findings:

- Both knee AP showed subperiosteal bone resorption along the medial aspect of both tibia. The growth plate of femur, tibia and fibula are irregularly widened with indistinct zone of provisional calcification. Adjacent metaphysis are sclerotic.

- Pelvis AP showed indistinct border or cortical bone, suggestive of subperiosteal bone resorption. Both sacroiliac joints are widened with indistinct border, suggestive of subchondral bone resorption. Both femoral heads are inferomedially slipped.

- Neck CT showed an oval enhancing mass in posteroinferior aspect of the right lobe of thyroid gland. 

- ^99mTc MIBI scan showed a hot uptake in the inferior aspect of thyroid gland on early phase image. A hot uptake lesion was remained, while uptake of both thyroid glands were washed out on 2hours delayed image.

- Laboratory findings : Ca/P 12.5/2.7 (8.2~10.5 / 2.3~4.5 mg/dL), iCa 6.1 (4.6~5.4 mg/dL), BUN/Cr 7/0.5 (5~23 / 0.5~1.4 mg/dL), ALP 14250 (40~250 IU/L), PTH 2600 (15~65 pg/mL)

Differential Diagnosis: Primary Hyperparathyroidism (by parathyroid adenoma)

                    Renal osteodystrophy

                    Osteoporosis

                    Rickets

                    Ankylosing spondylitis

Diagnosis: Primary hyperparathyroidism (by parathyroid adenoma)

Discussion: Hyperparathyroidism is a general term indicating an increased level of parathyroid hormone in blood. Primary hyperparathyroidism is characterized by increased parathyroid hormone secretion as a result of diffuse hyperplasia (10%), adenoma (90%), carcinoma (<1%). The fundamental biochemical marker of hyperparathyroidism is persistent hypercalcemia. Initial symptoms are related to urolithiasis, peptic ulcer, pancreatitis. Radiologic findings are bone resorption, bone sclerosis, and chondrocalcinosis.

Bone resorption can be categorized as subperiosteal, intracortical, endosteal, subchondral, subphyseal, trabucular, subligamentous, and subtendinous. Subperiosteal bone resorption is most frequent along the radial aspect of phalanges of the index and middle finger, terminal phalanges, medial aspect of tibia, humerus, and femur, ribs, and lamina dura. Subchondral resorption is frequent in the joint of axial skeleton, such as sacroiliac joint, sternoclavicular, symphysis pubis. Subchondral resorption of sacroiliac joint simulate radiologic finding of ankylosing spondylitis. In children with primary or secondary hyperparathyroidism, irregular radiolucent areas may appear in the metaphysic adjacent to growth plate, which simulates rickets. Trabecular resorption within medullary bone in advanced stage of disease, giving the speckled appearance of skull which is termed the “salt and pepper” appearance. Bone sclerosis is observed more frequently in renal osteodystrophy (secondary hyperparathyroidism), although it may be apparent in primary hyperparathyroidism. In primary hyperparathyroidism, bone sclerosis may be localized and patchy in the metaphysis of long bone, skull, vertebral endplates. Brown tumors were initially described as being characteristic of primary hyperparathyroidism, but more recently they have been noted with increasing frequency in secondary hyperparathyroidism as well. Brown tumors represent localized accumulation of fibrous tissue and giant cells, which may osteolytic lesion mimicking bone tumor. They appear as single or multiple well-defined lesions frequently eccentric or cortical in location.  

References:

Parathyroid disorders and renal osteodystrophy. In: Resnick D, Kransdorf MJ. Bone and joint imaging 3^rd ed. Philadelphia. Elsevier Saunders 2005: 603-611