It is functionally active chromaffin tumor, which may be located in the adrenal medulla or other sites of sympathetic ganglia or chromaffin tissue. This tumor stains deep brownish color when exposed to chromium salts. This tumor is derived from primitive cells originating in the neural crest, which can differentiate to form pheochromocytes. This tumor has a tendency to produce large amount of catecholamines, primarily norepinephrine.
Pheochromocytomas often involve the right rather than the left adrenal medulla and in 10% of cases it may be bilateral. This tumor tends to be circumscribed and yellowish brown, but occasionally this may attain a large size. Large growths frequently exhibit areas of necrosis, hemorrhage or cyst formation.
Pheochromocytomas may develop at all ages, but are usually encountered between the ages of 20 and 50 years. This tumor presents in a bizarre fashion which is often referred to as adrenal sympathetic syndrome. Paroxysmal or persistent arterial hypertension is there. The patient complains of sweating, palpitation and headache. Death may occur from myocardial infarction or cerebaro-vascular accident. The patient may present with diabetes mellitus.
Occasionally pheochromocytomas are due to increased secretion of epinephrine and norepinephrine. Usually patients with paroxysmal hypertension are more symptomatic than those with sustained hypertension. When the secretion is mainly epinephrine, the effects include sweating, tachycardia and hyperglycemia. However hypertensive episode may be stimulated by injection of drugs, e.g., histamine or glucagon or by injection of contrast materials used for arteriography.
Investigations-
1. It is confirmed by increased excretion rates of urinary epinephrine and norepinephrine or their metabolites.
2. Provocative test by intravenous administration of histamine.
3. Conventional urography.
4. Ultrasound.
5. CT scan.
6. Adrenal imaging.
7. Arteriography.
8. Adrenal venography.
Treatment-
The main treatment of pheochromocytoma is surgery. The place of medical treatment is restricted to-
1. Preoperative preparation.
2. For patients who refuse surgery.
3. For patients who have functioning metastases.