00:00
Paragangliomas are tumors
composed of chromaffin cells.
00:05
80% of Intra-adrenal pheochromocytomas
are paragangliomas.
00:10
Pheochromocytoma and extra-adrenal
sympathetic paragangliomas
almost always
secrete catecholamines.
00:17
These include norepinephrine,
epinephrine, and dopamine.
00:22
Although catecholamine-secreting
tumors are rare overall,
they are found in 0.5%
of patients with hypertension.
00:31
Pheochromocytomas account for 5%
of adrenal incidentalomas.
00:37
An incidentaloma is
a radiographic term
for a mass incidentally
found on imaging.
00:43
Most pheochromocytomas
secrete norepinephrine
resulting in episodic or sustained hypertension
as was present in our case.
00:52
Orthostatic hypotension
can also be seen
and likely reflects
low plasma volume.
00:57
Symptoms as described include
palpitations, tremor, pallor, and anxiety.
01:03
Less commonly, these patients
can present with papilledema,
diabetes mellitus,
and cardiomyopathy.
01:09
Most of these manifestations are from
elevated levels of blood pressure.
01:13
Approximately, 10%
of pheochromocytomas
and 20 to 50% of paragangliomas
are malignant.
01:21
Pheochromocytomas are seen with
multiple endocrine neoplasia syndromes.
01:27
Type 2A and 2B MEN syndromes include
neurofibromatosis type 1
and Von Hippel-Lindau syndrome.
01:35
Let’s review some of the multiple
endocrine neoplasia syndromes.
01:40
MEN 1 is caused by the inheritance
of one mutated allele
with a somatic mutation in other allele
and leads to neoplasias.
01:48
The most common presentation is with
a parathyroid adenoma, often multiple.
01:53
To confirm the
diagnosis of MEN 1,
this must be associated with
pancreatic islet cell tumors
or enteric tumors like a
gastrinoma or an insulinoma.
02:04
Pituitary adenomas
may also occur.
02:07
Other associations include carcinoid tumors
and adrenocortical adenomas.
02:12
MEN 2A most commonly manifests
with medullary thyroid carcinoma
in association with a pheochromocytoma
which is often multifocal
as well as parathyroid
hyperplasia.
02:24
MEN 2B manifests with
medullary thyroid carcinoma.
02:29
But here, although also associated
with pheochromocytomas
is also accompanied
by mucosal neuromas,
gastrointestinal
ganglioneuromas,
and patients may have
a Marfanoid body habitus.
02:42
Returning now to confirming the
diagnosis of pheochromocytoma,
the excessive secretion of catecholamines
or their metabolites
as measured in the plasma
or urine will help.
02:53
Evaluation is recommended for all
incidentally noted adrenal masses
or in the setting of
hereditary pheochromocytoma
or paraganglioma syndromes.
03:04
The sensitivity of plasma free
metanephrines is the highest
of any screening test in endocrinology
at 96-100%.
03:12
However, the specificity is
relatively low at 85-89%.
03:17
Bear in mind that
the pretest probability
based on the
patient’s presentation
in terms of signs and symptoms
can improve this.
03:26
Plasma free metanephrines
will reliably exclude
a pheochromocytoma
when negative.
03:32
But further testing is needed
to confirm the diagnosis
unless the result is
markedly abnormal,
often in the range of four times
the upper limits of normal.
03:43
Imaging follows the biochemical diagnosis
for radiographic localization.
03:49
Because most catecholamine-secreting tumors
are located in the abdomen,
a CT or MRI of the abdomen
is the best place to start.
03:58
If negative, an Iodine-123 MIBG
scan can be performed.
04:04
Adjunctive diagnostic tests are MRI
of the chest and the neck region
if you have not identified the
tumors within the abdomen.
04:17
Laparoscopic adrenalectomy is
the preferred treatment
for pheochromocytoma except in the
case of a large or malignant tumor
where an open
adrenalectomy is required.
04:28
Long-term follow up is needed for
pheochromocytoma and paragangliomas
due to difficulty distinguishing
benign from malignant tumors.
04:37
Metastases have been reported after 20 years of the diagnosis.
04:42
In addition to routine
clinical surveillance,
annual measurements of plasma
or urine metanephrines
is indicated to assess for a
current or metastatic disease.
04:53
Metastatic disease is managed
with additional surgery
and MIBG therapy as well as
chemotherapy and/or radiotherapy.