Moffitt AM Endo Report PEARLS 9/16: Brown tumors and hyperparathyroidism!

First, what are giant cell and brown tumors?! Two new diagnoses for me!

  • Giant cell bone tumors: primary bone tumors caused by osteoblast dysregulation, is rare and aggressive but benign. Most common in Asians (20% of Asians with bony lesions have this!), and can metastasize to soft tissue or lung. Treatment is surgical resection, or denosumab (monoclonal Ab targeting RANK ligand, which alters the balance between osteoclastic vs blastic activity).
  • Brown tumors: on imaging, very similar to giant cell bone tumors. This one is associated with CKD (2/2 hyperparathyroidism) and affects bone only (not soft tissue or lung). Amazingly, by treating the hyperparathyroidism (with surgery), bone can remodel and brown tumors can disappear (can take years)!!

Take-home point: for hypercalcemia, always start by checking a PTH. If it’s elevated, break it down into primary, secondary, and tertiary (pseudohyperparathyroidism) as this can affect your treatment (more details below). If somebody needs to go for parathyroidectomy, let your endocrine surgeons determine whether to get a sestamibi scan first, and monitor for hungry bone syndrome (low calcium) in the immediate post-op period!!

Other pearls from the morning!

  • Patients with CKD often have low calcium and high phosphate. If they also have hyperparathyroidism which causes hypercalcemia, worry about the calcium x phosphate product and calciphylaxis!
  • Hyperparathyroidism causes increased bone turnover and therefore increased risk of osteoporosis. To screen for osteoporosis in these patients, check radial bone density instead of traditional L-spine/hip DEXA because effects are preferentially seen here (rich in cortical bone)!
  • Great question about MEN syndromes: always think about these for patients with hyperparathyroidism (MEN 1 = parathyroid, pituitary, and pancreas; MEN 2 = parathyroid, medullary thyroid cancer, pheo) but no need for genetic screening on diagnosis of primary hyperparathyroidism. No need to worry about MEN for 2ndary/tertiary hyperparathyroidism.
  • Treatment for hyperparathyroidism!
    • Primary: 2/2 parathyroid adenoma or hyperplasia. Often asymptomatic. Ok to monitor unless pt meets criteria for surgery:
      • Symptomatic hypercalcemia
      • Ca >1 mg/dl about upper limit of normal
      • Urine calcium >400mg/24h (risk of stones)
      • Renal insufficiency
      • Osteoporosis
      • Young age (< 50)
    • Secondary: 2/2 CKD (low calcium, low active vit D). Treat with calcitriol (active vitamin D) when CKD pts have elevated PTH.
    • Tertiary: excessive PTH secretion by parathyroid gland after long period of 2ndary hyperparathyroidism. Treat with cinacalcet (activates calcium-sensing receptors) or surgery if refractory.
  • If a patient needs a parathyroidectomy, surgeons will determine whether they would like a sestamibi scan beforehand. Intra-op, they will check serial PTHs to make sure all of the parathyroid glands are removed! In the immediate post-op period (days), watch for hungry bone syndrome (severely low Ca, phos, and Mg) from high preop bone turnover and increased influx of calcium into bone from the sudden removal of high PTH levels on osteoclastic resorption (this is the presumed pathophys).Treatment includes calcium supplementation and bisphosphonates.
    • A great question came up about ways to prevent hungry bone syndrome – found an article suggesting that bisphosphonate pretreatment may help (but no prospective studies)! PMID 16622740.



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