Pheochromocytoma
Pheochromocytomas and paragangliomas are catecholamine- producing tumors derived from the sympathetic or parasympathetic nervous system.
These tumors may arise 1.sporadically 2.inherited as features of multiple endocrine neoplasia type 2 3.several other pheochromocytoma-associated syndromes : Neurofibromatosis, von Hippel- Lindau, succinate dehydrogenase (B,C,D)
Epidemiology Pheochromocytoma is estimated to occur in 2–8 of 1 million persons per year about 0.1% of hypertensive patients harbor a pheochromocytoma. mean age at diagnosis is about 40 years, although the tumors can occur from early childhood until late in life.
The "rule of tens" for pheochromocytomas states that 1.10% are bilateral 2.10% are extraadrenal 3.10% are malignant
Clinical Features clinical presentation is variable, ranging from 1.an adrenal incidentaloma 2.hypertensive crisis with associated cerebrovascular or cardiac complications.
Diagnosis
Treatment Complete tumor removal is the ultimate therapeutic goal.
Preoperative patient preparation is essential for safe surgery Adrenergic blockers ( phenoxybenzamine ) should be initiated at relatively low doses (e.g., 5–10 mg orally three times per day) and increased as tolerated every few days. Adequate alpha blockade generally requires 7 days, with a typical final dose of 20–30 mg phenoxybenzamine three times per day.
Oral prazosin or intravenous phentolamine can be used to manage paroxysms while awaiting adequate alpha blockade. Before surgery, blood pressure should be consistently below 160/90 mmHg, with moderate orthostasis.
Beta blockers (e.g., 10 mg propranolol three to four times per day) can be added after starting alpha blockers and increased as needed if tachycardia persists. Other antihypertensives, such as calcium channel blockers or angiotensin-converting enzyme inhibitors, have been used when blood pressure is difficult to control with phenoxybenzamine alone. Because patients are volume-constricted, liberal salt intake and hydration are necessary to avoid orthostasis.