Diagnosis
Marfan's syndrome with aortic dissection complicated by
pheochromocytoma and medullary carcinoma of the thyroid gland. CT
of the aorta confirmed a type B dissection beginning just distal to
the origin of left subclavian artery and extending to the level of
the aortic bifurcation (figure 1). There was no evidence of leakage
or rupture. CT images through the upper abdomen revealed a mass
that appeared to be invading or displacing the right lobe of the
liver (figure 2). Most of the mass exhibited some degree of
contrast enhancement, with low-attenuation areas posteriorly. MRI
evaluation of the mass demonstrated low signal on T1 with very high
signal throughout most of the mass on T2-weighted images (figures 3
and 4). T2-weighted images also revealed areas of low signal
posteriorly, with fluid-fluid levels indicating cyst formation,
necrosis, and/or hemorrhage. The mass exhibited a mild degree of
enhancement after gadolinium administration. Diagnostic
considerations include hepatic masses, such as cavernous
hemangioma, hemorrhagic adenoma, hepatocellular carcinoma, and
metastasis, as well as adrenal masses, such as hemorrhagic adenoma,
adrenal carcinoma, metastases, or pheochromocytoma. Serum and urine
catecholamines subsequently were found to be quite elevated, and
pheochromocytoma was confirmed after excising the mass (following
preoperative prophylaxis with phenoxybenzamine). Review of the
chest CT revealed a low-attenuation lesion in the left lobe of the
thyroid gland, and the serum calcitonin level was found to be
elevated. Total thyroidectomy was performed, and medullary
carcinoma confined to the left lobe of the thyroid gland was
confirmed.
Discussion
This patient's triad of Marfanoid habitus (arachnodactyly,
increased lower extremity-to-trunk ratio, and scoliosis),
pheochromocytoma, and medullary carcinoma of the thyroid gland
supports a diagnosis of multiple endocrine neoplasia type IIb.
However, this patient did not exhibit the characteristic mucosal
neuromas usually seen in this disorder. The MEN IIb syndrome
usually is inherited as an autosomal dominant trait. The patient's
parents exhibited no manifestations of the disease, but the
patient's sister and two sons do exhibit Marfanoid body habitus. In
Marfan's syndrome, aortic dissection and aneurysm are due to cystic
medionecrosis, probably related to production of faulty elastin
fibers. Other cardiovascular abnormalities associated with Marfan's
syndrome include mitral valve prolapse, mitral regurgitation, and
aortic root dilation with regurgitation. Although the Marfanoid
habitus is a relatively common phenotypic expression in MEN IIb,
the cardiovascular manifestations of Marfan's syndrome, including
aortic dissection as in this case, have not been described
previously in MEN IIb. Whatever the ultimate genetic explanation
for the appearance of pheochromocytoma and aortic dissection in
this patient, this combination of pathology provided an interesting
diagnostic and therapeutic challenge. The tremendous blood pressure
and cardiac output fluctuations associated with catecholamine
release by the pheochromocytoma may have accelerated any
preexisting weakness in the tunica media and perhaps led to
premature dissection.
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