Imaging features of primary hyperPTH?
(excess PTH leads to excessive osteoclastic activity)
1) SUBPERIOSTEAL bone resorption
- Acro-osteolysis
- classically affects the radial aspects of the proximal and middle phalanges of the 2nd and 3rd fingers
- medial aspect of tibia, femur, humerus
- lamina dura of mandible: floating teeth (not specific)
2) SUBCHONDRAL bone resorption:
- lateral end of the clavicles
- symphysis pubis
- sacroiliac joints
3) SUBLIGAMENTOUS resorption
- ischial tuberosity
- trochanters
- inferior surface of calcaneus and clavicle
4) Brown tumors. Expansile well-defined geographic lytic lesions with narrow zone of transition. (mandible, hands, pelvis, ribs)
- Osteopenia
- Osteosclerosis (diffusely coarsened trabeculae, rugger jersey spine, salt and pepper skull; UNLIKE pagets which is usu not so uniform)
What are the 3 types of hyperparathyroidism
- Primary
- due to hyperfunctioning parathyroid adenoma (80%) > gland hyperplasia (10-15%) > carcinoma (5%) [can be confirmed on Technetium nuclear scintigraphy (TS) with sestamibi/tetrosfosmin] - Secondary
- caused by chronic hypocalcaemia with renal osteodystrophy being the most common cause (others include malnutrition, vitamin D deficiency)
- results in parathyroid hyperplasia - Tertiary
- autonomous parathyroid adenoma caused by the chronic overstimulation of hyperplastic glands in renal insufficiency
Imaging findings of secondary (or tertiary) hyper PTH?
The findings in secondary (and tertiary) hyperparathyroidism are often associated with the osteosclerosis of renal osteodystrophy and the osteomalacia of vitamin D deficiency:
- subperiosteal bone resorption
- osteopenia
- osteosclerosis, e.g. rugger jersey spine
- soft tissue calcification/chondrocalcinosis
- superscan: generalised increased uptake on Tc-99m pertechnetate bone scan (cf
superior and inferior rib notching
