Pathology of the parathyroid glands

Question 1

what is the most common cause of primary hyperparathyroidism?

Answer 1

parathyroid gland adenoma

Question 2

what characterizes primary hyperparathyroidism?

Answer 2

• lesions WITHIN the parathyroid gland that secrete excessive PTH
• autonomous overproduction of PTH NOT suppressed by the negative feedback inhibition of elevated serum calcium

Question 3

how does excess PTH cause hypercalcemia?

Answer 3

• 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

Question 4

what is the main cause of flank pain / hematuria / renal stone formation?

Answer 4

filtered load of calcium exceeds kidney’s ability for reabsorption - calcium is still excreted in urine

Question 5

what are the clinical symptoms of primary parathyroidism?

Answer 5

STONES - kidney stones
BONES - osteomalacia, cystic lesions, brown tumors (osteitis fibrosa cystica)
GROANS - high calcium - produces gastrin - PUD (most common)
MOANS - depression

Question 6

what type of tumor is a parathyroid adenoma?

Answer 6

SOLITARY

Question 7

how is parathyroid carcinoma diagnosed?

Answer 7

• breaks through capsule

- metastasis

Question 8

what differences are seen between normal parathyroid tissue and parathyroid adenoma?

Answer 8

• no fat cells
• primarily chief cells
• thin rim of normal parathyroid tissue

Question 9

what is the second most common cause of primary hyperparathyroidism? what are the clinical features?

Answer 9

parathyroid hyperplasia

• all 4 glands are enlarged
• hyperplastic glands usually LACK the usual fat cells

Question 10

parathyroid hyperplasia is most common in patients with what syndrome?

Answer 10

MEN syndrome

Question 11

what is MEN syndrome?

Answer 11

parathyroid disease associated with tumors of the pancreas, adrenal, thyroid, and pituitary glands

Question 12

how is parathyroid hyperplasia different from adenoma histologically?

Answer 12

hyperplasia - NO rim of normal parathyroid tissue

Question 13

definition: secondary hyperparathyroidism

what is the most common cause?

Answer 13

parathyroid hyperplasia due to hypocalcemia from some OTHER causes

most common - chronic renal failure (low calcium and high PTH)

Question 14

what constitutes a major problem stemming from secondary hyperparathyroidism?

Answer 14

bone disease (“renal osteodystrophy”leading to brown tumors)

Question 15

parathyroid carcinoma: characteristics

Answer 15

• low malignant potential

- 50% cured by en bloc resection

Question 16

what is the main morphological characteristic of parathyroid carcinoma?

Answer 16

FIBROUS BANDS (90% present)

Question 17

parathyroid carcinoma: histology

Answer 17

• uniform cells resembling normal parathyroid cells
• cells arrayed in nodular or trabecular patterns
• cells enclosed in fibrous bands

Question 18

what are the only reliable criteria for diagnosing parathyroid carcinoma?

Answer 18

invasion of surrounding tissues and metastasis

Question 19

what are the causes of hypoparathyroidism?

Answer 19

• autoimmune disorder (main cause)
• iatrogenic
• DiGeorge syndrome

Question 20

hypoparathyroidism: signs and symptoms?

Answer 20

• mental changes
• circumoral paresthesia
• chvotek sign
• trousseau sign

progresses to convulsions and tetany

Question 21

how is hypoparathyroidism diagnosed?

Answer 21

decreased serum calcium and increased serum phosphate

Question 22

hypoparathyroidism: treatment

Answer 22

• vitamin D
• calcium gluconate cookies
• recombinant human PTH