Endocrine parathyroid tumors Flashcards
What is the histologic description of a parathyroid
adenoma?
A parathyroid adenoma appears as a hypercellular gland
consisting of chief and oncocytic cells with decreased intercellular fat.
What are some intraoperative techniques used to
identify a parathyroid adenoma?
Localization of an adenoma can be assisted by preoperative injection of methylene blue, which stains abnormal para-thyroid glands preferentially. Preoperative injection of sestamibi in conjunction with intraoperative gamma probes can also be used to identify a parathyroid gland.
What is the most sensitive imaging study for identifying the location of a parathyroid adenoma?
Technetium-99 m sestamibi with single-photon emission CT
(or SPECT; sensitivity from 70 to 100%). Ultrasound imaging
is reported to be successful in localization in 50 to 90% of cases but is highly user dependent. 4D CT scan is an emerging technology, but the localization success rate remains to be determined.
How frequently is primary hyperparathyroidism
caused by a single adenoma versus four-gland hyperplasia?
A single parathyroid adenoma is the cause in 80 to 85% of
cases and four-gland hyperplasia in 10 to 15% of cases.
Other causes of primary hyperparathyroidism include double adenomas (5%) and parathyroid carcinoma (< 1%).
What features of a patient with hypercalcemia and elevated PTH are more concerning for a para-
thyroid carcinoma compared with benign parathyroid adenoma?
Aside from a palpable neck mass, other features worrisome
for parathyroid carcinoma include markedly elevated serum calcium levels (> 14), markedly elevated PTH, concomitant
renal and bone disease, symptoms consistent with severe hypercalcemia, and evidence of invasion such as recurrent
laryngeal nerve palsy.
What proportion of primary hyperparathyroidism
is caused by parathyroid carcinoma?
About 0.1 to 1% of persons with primary hyperparathy-
roidism have a parathyroid carcinoma.
What are the incidence and prevalence of parathyroid carcinoma?
Parathyroid carcinoma is one of the rarest of all human cancers, with an incidence of 0.015 per 100,000 population and a prevalence of 0.005% in the United States.
How does the patient population with parathyroid
carcinoma compare with patients with parathyroid
adenoma?
There is an even distribution of males and females with parathyroid carcinoma, whereas there is female predominance in parathyroid adenoma. Patients on average are younger with parathyroid carcinoma (average age in 40s) compared with parathyroid adenoma (average age 50 to 60s).
What feature on physical examination is most concerning for parathyroid carcinoma?
A palpable neck mass (reported in 30 to 76% of patients
with parathyroid carcinoma), which is rarely associated with
a benign adenoma
What is the gross pathologic description of a parathyroid carcinoma compared with a benign
adenoma?
Benign adenomas are generally soft, round, or oval and
reddish brown. Parathyroid carcinoma is frequently a large,
lobulated, and firm to stony-hard mass, with a grayish white capsule that is frequently adherent or invasive to surrounding tissues.
What is the American Joint Committee on Cancer
(AJCC) staging system for parathyroid carcinoma?
There is no AJCC staging system for parathyroid carcinoma
because of its low incidence.
What is the most common cause of death in
patients with parathyroid carcinoma?
Patients often die from the effects of excessive PTH
secretion and uncontrolled hypercalcemia rather than growth from tumor mass.
What is the best prognostic factor in parathyroid
carcinoma?
Early recognition and complete surgical resection at initial
operation offer the best prognosis.
Describe the prognosis for parathyroid carcinoma.
Surgical cure and survival can be achieved in patients
undergoing an R0 (complete) resection. Patients with recurrent disease can be palliated with aggressive surgical
therapy and calcimimmetic medications such as cincalcet.
What is the preferred treatment approach to
parathyroid carcinoma?
Parathyroid carcinoma should be aggressively treated with en bloc resection of the tumor, ipsilateral central neck components, including thyroid lobectomy, tracheoesophageal soft tissue, and central lymph node dissection.
