Neuroscience · Year 2 · from Neuroscience
Case 3: Pheochromocytoma - Catecholamine Excess
Patient Presentation
Demographics: 38-year-old female
Chief Complaint: Episodes of severe headache, palpitations, and sweating
History of Present Illness: A 38-year-old woman presents with a 6-month history of intermittent episodes characterized by severe throbbing headache, pounding heartbeat, and profuse sweating. Episodes occur 2-3 times per week, last 20-30 minutes, and are accompanied by intense anxiety and pallor. She has noted progressively worsening hypertension, with recent readings at home reaching 200/120 mmHg during episodes. Between episodes, her blood pressure is elevated but more modest (150/95 mmHg). She has lost 10 pounds despite normal appetite. Family history is significant for a father who died suddenly at age 42 and a brother with thyroid cancer.
Physical Examination:
- Vital signs (during episode): BP 210/125, HR 124, RR 20, T 37.4C
- Vital signs (baseline): BP 158/98, HR 88
- General: Diaphoretic, anxious, pale during episode
- Cardiovascular: Tachycardic, regular rhythm, no murmurs
- Abdominal: Palpation of left upper quadrant precipitates hypertensive episode (suggestive of tumor manipulation)
Workup:
- Plasma free metanephrines: Markedly elevated (metanephrine 856 pg/mL, normal <57; normetanephrine 1243 pg/mL, normal <148)
- 24-hour urine catecholamines and metanephrines: Elevated
- CT abdomen with contrast: 4 cm left adrenal mass with heterogeneous enhancement
- MIBG scan: Avid uptake in left adrenal gland, no metastatic disease
- Genetic testing: RET proto-oncogene mutation positive (MEN2A)
- Serum calcitonin: Elevated (medullary thyroid cancer screening)
Diagnosis: Pheochromocytoma in the setting of Multiple Endocrine Neoplasia type 2A (MEN2A)
Treatment:
- Alpha-blockade with phenoxybenzamine initiated 2 weeks before surgery (non-competitive alpha antagonist; titrated to postural hypotension)
- Beta-blockade added AFTER adequate alpha-blockade (to avoid unopposed alpha stimulation)
- High-sodium diet and fluids to expand contracted intravascular volume
- Laparoscopic adrenalectomy after adequate preparation
- Screening for medullary thyroid carcinoma and hyperparathyroidism (MEN2A components)
- Genetic counseling and family screening
Clinical Pearl: Pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells, most commonly arising in the adrenal medulla. The episodic nature of symptoms reflects intermittent catecholamine release. The classic triad is headache, diaphoresis, and palpitations. Alpha-blockade must precede beta-blockade to prevent unopposed alpha-mediated vasoconstriction during catecholamine surges. The "10% rule" historically stated 10% are bilateral, 10% extra-adrenal, 10% malignant, and 10% familial, but genetic testing reveals hereditary syndromes in up to 40% of cases.
Clinical Image
Image Description: Clinical photograph demonstrating unilateral Horner syndrome with ptosis (drooping eyelid), miosis (constricted pupil), and apparent enophthalmos on the affected side compared to the normal contralateral eye.
Attribution: Image from Wikimedia Commons (https://commons.wikimedia.org/), Creative Commons Attribution-ShareAlike license.