Joint Program in Nuclear Medicine
Hemorrhage into a Parathyroid Adenoma
David A. Israel, MD PhD
April 4, 2000
Presentation
A 74 year old woman presented with stridor and dysphagia. The emergency
room personnel noticed an 'abnormal' appearance of the neck at the time
of intubation. A CT scan was obtained. Shortly thereafter, a gallium scan
was requested. Several days later, the same patient had imaging performed
with sestamibi.
Imaging Findings
CT
CT scan of the neck and chest shows a soft tissue,
slightly high attenuation, heterogeneous, infiltrative, mass-like opacity
involving the middle mediastinum, extending posterior to the upper trachea.
It is inseparable from the upper esophagus and extends medial to the aortic
arch from which it is also inseparable. The arch appears pushed laterally
by this opacity. The mass continues up into the retropharyngeal and pericervical
regions, and extends inferiorly to the level of the carina. Small bubbles
of gas are seen in the more superior aspect adjacent to the right clavicle
(arrow shows bubbles; T = trachea; M = mass;
C = clavical). There is no evidence of lymphadenopathy.
Gallium Scintigraphy
Gallium scan shows an approximately 4-cm diameter
region of moderately intense Gallium uptake in the lower neck (shown
by arrow), corresponding to the location of an open surgical biopsy
which had been performed on the mass-like lesion following the recent neck
and chest CT. Most of this soft-tissue mass shows no Gallium avidity.
Surgical biopsy result: blood, few cells, no sign of lymphoma or other
recognizable tumor.
Routine labs reveal elevated serum Ca: Total 11.9 (Normal: 8.8 - 10.5);
Ionic 1.56 (Normal: 1.13 - 1.32)
Sestamibi Scintigraphy
Images at 3 hours post-injection of sestamibi reveal
a large focus of sestamibi uptake in the right lower neck and a small focus
of sestamibi uptake in the left upper neck (shown
by arrow). The findings are consistent with bilateral parathyroid adenomas.
(A parathyroid adenoma had been suspected on the basis of the elevated
serum calcium levels. The measured PTH was 208 pg/ml (Normal range 10 -
60) ).
Follow-up
Subsequent surgery revealed a normal right lower parathyroid gland. The
right upper parathyroid was not in a normal location. There was an indurated
lesion in the right paratracheal lower neck consistent with an ectopic
right upper parathyroid adenoma, communicating with a large hematoma. Pathology
confirmed bilateral benign parathyroid adenomas.
Follow-up
Subsequent surgery revealed a normal right lower parathyroid gland. The
right upper parathyroid was not in a normal location. There was an indurated
lesion in the right paratracheal lower neck consistent with an ectopic
right upper parathyroid adenoma, communicating with a large hematoma. Pathology
confirmed bilateral benign parathyroid adenomas.
Diagnosis
-
Two Parathyroid Adenomas
-
Hemorrhage within one of the Parathyroid Adenomas
Discussion
Hemorrhage within a parathyroid adenoma is a known, though rare complication,
with fewer than cases reported in the literature as of July 1995. The hemorrhage
tears through the thin capsule and dissects into cervical and mediastinal
tissues.
Parathyroid adenoma is a benign neoplasm of the parathyroid which usually
comes to clinical attention because of overproduction of parathyroid hormone.
-
Solitary parathyroid adenomas account for roughly 80% of cases of primary
hyperparathyroidism.
-
The next most frequent cause of primary hyperparathyroidism is termed chief
cell parathyroid hyperplasia, in which all of the parathyroid glands are
hyperfunctioning.
-
In a few percent of cases, as in the presented case, more than one, but
not all, of the glands are hyperfunctioning, so-called double or multiple
adenoma.
Parathyroid adenomas are thought to be the result of a somatic mutation
in a parathyroid cell which results in a clonal expansion of mutant cells.
A variety of different chromosomal deletions have been demonstrated in
different adenomas, with probable deletion of tumor suppressor genes. The
incidence increases in those exposed to neck irradiation, with a lag time
of decades, but in most cases, no history of mutagen exposure is elicited.
The disease occurs in all age groups but has its peak incidence between
the 3rd and 5th decades, with an estimated annual incidence of 2 per 1000
population. However, the clinical course is variable, with some cases remaining
essentially asymptomatic, and others presenting acutely with severe dehydration
and even coma, the hypercalcemic parathyroid crisis. Excessive levels of
parathyroid hormone lead to presenting features such as nephrolithiasis
and impaired renal function, peptic ulcers, mental status changes, and
bone resorption, leading to osteitis fibrosa cystica and, in some patients,
osteopenia. Bone involvement tends to affect cortical bone more than trabecular
bone. Other manifestations include proximal muscle weakness and atrophy,
chondrocalcinosis, and pseudogout.
The diagnosis of primary hyperparathyroidism is typically confirmed
by direct measurement of circulating PTH levels by immunoassay. The first
line therapy for symptomatic patients is surgical excision. The surgery
is low-risk, curative, and has a success rate of over 90% in experienced
hands. Asymptomatic patients, particularly older patients who wish to avoid
surgery may be followed.
In many practices, resectional surgery is undertaken without the use
of prior imaging. Since about 80% of cases are due to a solitary adenoma,
when such a tumor is found by exploration and removed, and if normal parathyroid
tissue can be demonstrated in at least one other gland (to exclude cases
of chief cell parathyroid hyperplasia), chances of success are good. However,
this approach will fail in the case of multiple adenomas. At the other
extreme, even when all four glands are identified at surgery, there are
documented cases of presence of 5 or 6 glands, and ectopically located
glands (e.g: mediastinal) are not rare. To avoid failures in such cases,
or to rectify them at re-operation, imaging can be helpful.
Imaging techniques include ultrasound, CT, angiography, and of course,
scintigraphy. Ultrasound and CT can identify nodular structures, and differentiate
solid tissue from cysts, but cannot distinguish between a thyroid nodule,
a lymph node, and a parathyroid adenoma.
Scintigraphy can be used to distinguish between thyroid and parathyroid
tissue, and identify larger than normal foci of parathyroid tissue. Two
methods are in use. The method used in the case presented uses sestamibi,
which is taken up by both thyroid and parathyroid tissue, but washes out
of the thyroid relatively rapidly, leaving predominantly parathyroid activity
on delayed images. An older method uses a combination of images obtained
with two tracers; a pertechnetate image, depicting only thyroid uptake,
is subtracted from a thallium image, which depicts the combination of thyroid
and parathyroid uptake. The difference image represents foci of parathyroid
tissue.
References
Case Records of the MGH, New England Journal of Medicine 333(3) 175-181,
July 1995.
Isselbacher, K. et. al, Harrison’s Principles of Internal Medicine,
13th Ed., McGraw-Hill, 1994.
Murray, I.P.C, Ell, P.J. Nuclear Medicine in Clinical Diagnosis and
Treatment, 2nd Ed. Churchill-Livingstone, 1999.
Wilson, J.D. et al, Williams Textbootk of Endocrinology, 9th Ed., W.B.
Saunders, Philadelphia 1998.
Click here to go to Joint
Program in Nuclear Medicine home page and Copyright notice.
J. Anthony Parker, MD PhD, Tony_Parker@CareGroup.Harvard.edu