Which is the following is not associated with the condition shown on the CT films of a 57-year-old lady with hypertension?
{morfeo 53}
A. It can occur alone, or be associated with some hereditary disorders, and all the hereditary forms are autosomal recessive
B. Even after successful surgery, 27% to 38% of patients continue to have residual nonparoxysmal hypertension.
C. Although a few patients remain hypertensive in the immediate post-operative period, most require treatment for hypotension.
D. In 10% to 15% of patients, hypoglycemia may occur in the period immediately after tumor removal.
Answer: A
The CT film shows a malignant pheochromocytoma on the right side.
Pheochromocytoma is often called the “10% tumor” because 10% are bilateral, 10% are malignant, 10% occur in children, 10% are extra-adrenal, and 10% are familial.
All hereditary forms of pheochromocytoma are autosomal dominant. The conditions include:
1. multiple endocrine neoplasia type II (MEN2)
2. von Hippel-Lindau (VHL) disease
3. von Recklinghausen’s neurofibromatosis or neurofibromatosis type 1 (NF1)
4. familial paraganglioma (PGL) syndromes 1 and 4.
In 10% to 15% of patients, transient hypoglycemia can occur due to the removal of catecholamine suppression of insulin secretion. Frequent glucose monitoring in the post-operative period is necessary. In the period immediately after tumor removal, it is advisable to prevent hypoglycemia by infusion of 5% dextrose immediately after tumor removal and continuing for several hours thereafter. Although a few patients remain hypertensive in the immediate post-operative period, most require treatment for hypotension, which is best managed by administration of fluids.
Post-operative hypoglycemia is transient, whereas low blood pressure and orthostatic hypotension may persist for up to a day or more after surgery and require care with assumption of sitting or upright posture.
Reference
1. Pheochromocytoma: An Update on Risk Groups, Diagnosis, and Management. Mary Ann Nguyen-Martin, MD, Gary D. Hammer, MD, PhD. Hospital Physician February 2006
2. Lam KY, Chan AC, Wong WM, Lam KS.A review of clinicopathologic features of pheochromocytomas in Hong Kong Chinese. Eur J Surg Oncol. 1993 Oct;19(5):421-7.
Twenty-two Chinese patients with pheochromocytomas including 18 surgical and four autopsy cases were reported. The incidence at autopsy was 0.048%. The tumours were most common in the sixth and the fourth decades in males and females, respectively. There was no sex predilection. The incidence of bilaterality was 4.5% and the tumours were more common on the right side. 9.1% of the tumours were malignant and they were larger than their benign counterparts. Solid and diffuse pattern and mixed pattern were the most common histologic patterns. Minor histological features included hyaline globules (64%), nuclear pseudo-inclusions (55%), lipid degeneration (4.5%) and peri-adrenal brown fat (18%). All of them were strongly positive for the three pan-neuroendocrine markers (neuron-specific enolase, synaptophysin and chromogranin) confirming the usefulness of these markers in diagnosing pheochromocytoma.
3. FKW Chan, KL Choi, SC Tiu, CC Shek, TK Au Yong. A case of giant malignant phaeochromocytoma. Hong Kong Med J 2000;6:325-8. (free fulltext at HKMJ website here)
Malignant phaeochromocytoma is defined as the presence of tumour deposits at sites that are normally devoid of chromaffin cells. We report on a 63-year-old man who had a giant malignant phaeochromocytoma of the right adrenal gland that encased the inferior vena cava. The urinary excretion rates of catecholamines and their metabolites were normal, except for normetanephrine, which was excreted at a higher rate than normal. The tumour was surgically unresectable by laparotomy. Postoperatively, the patient was given a 4-month trial of subcutaneous octreotide and intravenous meta-iodobenzylguanidine I 131. Occult lung secondary tumours were first detected by meta-iodobenzylguanidine scintigraphy after 2 years, and the patient died of bone and lung metastases 1 year later. Because phaeochromocytoma is rare, local experience in managing this disease is limited. This report alerts physicians of the methods of diagnosing and managing surgically unresectable malignant phaeochromocytoma.
4. SEVERE POST-OPERATIVE HYPOGLYCEMIA COMPLICATING ADRENALECTOMY FOR PHEOCHROMOCYTOMA N.C. HODGE, M.D.†, S.D.DEJOY III, M.D.†, C. R. MCHENRY, M.D.‡ Departments of Anesthesia† and Surgery‡, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH (Weblink here)