Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Ectopic thyrotropin secreting pituitary adenoma concomitant with papillary thyroid carcinoma: Case report

RATIONALE

Ectopic thyrotropin (TSH)-secreting pituitary adenomas are exceedingly rare. To date, there are only 6 cases reported. Here, we describe an even rarer ectopic TSH-secreting pituitary adenoma (TSH-oma) concomitant with papillary thyroid carcinoma.

PATIENT CONCERNS

A 27-year-old female was admitted to the hospital in 2002 for neck enlargement and palpitation. Thyroid function test showed increased thyroid hormones and unrepressed TSH. Thyroid ultrasound examination displayed diffuse goiter. The patient was presumptively diagnosed as primary hyperthyroidism and treated with anti-thyroid drugs. Her condition was then improved, but the serum TSH was persistently unrepressed. Therefore, central hyperthyroidism due to TSH-oma or pituitary resistance to thyroid hormone (PRTH) was suspected. Pituitary magnetic resonance imaging (MRI) examination was deservedly performed to rule out TSH-oma, which turned out to be normal. In addition, T3 suppression test was negative. Thus, PRTH, as an uncommon cause of inappropriate TSH secretion, was regarded as the working diagnosis. Triiodothyroacetic acid, which was reported to be effective for PRTH, was then administrated. But it did not work well. To control the symptoms completely and normalize the level of thyroid hormones, radioiodine therapy was carried out in 2007, followed by levothyroxine replacement therapy. Consequently, the symptoms were relieved, whereas serum TSH remained at high levels even with adequate levothyroxine. Unexpected, thyroid papillary carcinoma and a neoplasm in her nasopharynx were successively detected in 2012, which were then removed by surgery. Somewhat interestingly, the serum TSH declined to normal after the operation.

DIAGNOSES

The patient was ultimately diagnosed as an ectopic TSH-secreting pituitary adenoma concomitant with papillary thyroid carcinoma.

INTERVENTIONS

Thyroidectomy and removal of the ectopic TSH-secreting pituitary adenoma by surgery were carried out, followed by levothyroxine replacement therapy.

OUTCOME

Three years after the surgery, the patient felt well with levothyroxine 125ug daily. Serum thyroid hormones and TSH kept in normal and no signs of neoplasm recurrence.

LESSONS

Although extremely rare, ectopic TSH-secreting pituitary adenoma, as an uncommon cause of thyrotoxicosis, should be taken into consideration among those who have a longstanding hyperthyroidism with unsuppressed TSH.