Flashcards in Pathology of the parathyroid glands Deck (22):
what is the most common cause of primary hyperparathyroidism?
parathyroid gland adenoma
what characterizes primary hyperparathyroidism?
- lesions WITHIN the parathyroid gland that secrete excessive PTH
- autonomous overproduction of PTH NOT suppressed by the negative feedback inhibition of elevated serum calcium
how does excess PTH cause hypercalcemia?
- increased bone resporption and calcium mobilization from bone
- increased renal tubular reabsorption of calcium in urine
- increased urinary excretion of phosphate
- increased renal synthesis of vitamin D - enhancing calcium absorption in gut
what is the main cause of flank pain / hematuria / renal stone formation?
filtered load of calcium exceeds kidney's ability for reabsorption - calcium is still excreted in urine
what are the clinical symptoms of primary parathyroidism?
STONES - kidney stones
BONES - osteomalacia, cystic lesions, brown tumors (osteitis fibrosa cystica)
GROANS - high calcium - produces gastrin - PUD (most common)
MOANS - depression
what type of tumor is a parathyroid adenoma?
how is parathyroid carcinoma diagnosed?
- breaks through capsule
what differences are seen between normal parathyroid tissue and parathyroid adenoma?
- no fat cells
- primarily chief cells
- thin rim of normal parathyroid tissue
what is the second most common cause of primary hyperparathyroidism? what are the clinical features?
- all 4 glands are enlarged
- hyperplastic glands usually LACK the usual fat cells
parathyroid hyperplasia is most common in patients with what syndrome?
what is MEN syndrome?
parathyroid disease associated with tumors of the pancreas, adrenal, thyroid, and pituitary glands
how is parathyroid hyperplasia different from adenoma histologically?
hyperplasia - NO rim of normal parathyroid tissue
definition: secondary hyperparathyroidism
what is the most common cause?
parathyroid hyperplasia due to hypocalcemia from some OTHER causes
most common - chronic renal failure (low calcium and high PTH)
what constitutes a major problem stemming from secondary hyperparathyroidism?
bone disease ("renal osteodystrophy"leading to brown tumors)
parathyroid carcinoma: characteristics
- low malignant potential
- 50% cured by en bloc resection
what is the main morphological characteristic of parathyroid carcinoma?
FIBROUS BANDS (90% present)
parathyroid carcinoma: histology
- uniform cells resembling normal parathyroid cells
- cells arrayed in nodular or trabecular patterns
- cells enclosed in fibrous bands
what are the only reliable criteria for diagnosing parathyroid carcinoma?
invasion of surrounding tissues and metastasis
what are the causes of hypoparathyroidism?
- autoimmune disorder (main cause)
- DiGeorge syndrome
hypoparathyroidism: signs and symptoms?
- mental changes
- circumoral paresthesia
- chvotek sign
- trousseau sign
progresses to convulsions and tetany
how is hypoparathyroidism diagnosed?
decreased serum calcium and increased serum phosphate