LWBK1006-25 LWW-Govindan-Review December 12, 2011 19:21
Chapter 25•Cancer of the Endocrine System 361represent the most widely used methods to treat malignant hypercalcemia.
Mithramycin has been used in the past to treat metastatic parathyroid car-
cinoma. Cinacalcet (Sensipar) directly lowers PTH levels by increasing the
sensitivity of calcium-sensing receptors on chief cells of the parathyroid
gland to extracellular calcium. It also results in concomitant serum cal-
cium decrease. Calcitonin can also be used to treat hypercalcemia and has
an analgesic effect in cases of pathologic fracture.Answer 25.19. The answer is A.
Several genetic defects have been reported to be associated with parathy-
roid cancer. Mutations of the HRPT2 gene (1q25-31) have been described
in this disease, most commonly in association with the hyperparathy-
roidism jaw tumor syndrome. However, many sporadic parathyroid carci-
nomas exhibit defects in this gene. This gene codes for a tumor suppressor
protein called “parafibromin,” whose function is not yet known. Allelic
loss in several chromosomes has been noted, but other than HRPT2, no
gene has definitively been associated with parathyroid carcinoma. RET
proto-oncogene mutation is not associated with parathyroid carcinoma.Answer 25.20. The answer is A.
Parathyroid cancer is rare enough that no staging system has been estab-
lished. A palpable mass is virtually never present with benign parathy-
roid adenomas or hyperplasia. The reported overall 5-year survival rate
is approximately 50% to 75%.Answer 25.21. The answer is B.
This patient has MEN1 syndrome because his presentation includes
pituitary adenoma and hyperparathyroidism. Prolactin-producing
pituitary adenomas are treated initially with dopamine agonists;
transsphenoidal resection is reserved as a second-line treatment. Subto-
tal parathyroidectomy (or total parathyroidectomy with autotransplan-
tation of a parathyroid tissue in the arm) is the standard approach in
treating hyperparathyroidism in MEN1 syndrome. Further evaluation is
warranted to exclude pancreatic neuroendocrine tumors possibly produc-
ing gastrin, especially in the presence of gastrointestinal symptoms.Answer 25.22. The answer is C.
Hyperparathyroidism is the most common manifestation in this disor-
der. The other endocrine disorders include pituitary adenomas, pancreatic
neuroendocrine tumors, carcinoid tumors, and occasionally adrenocorti-
cal adenomas. Other manifestations include lipomas, collagenomas, and
angiofibromas.Answer 25.23. The answer is D.
Virtually 100% of patients with MEN2A have C-cell hyperplasia or MTC;
50% have pheochromocytoma, and 20% to 30% have hyperparathy-
roidism. Diffuse neuronal hypertrophy is part of MEN2B.