Bilateral Adrenal Masses: Phaeochromocytoma or Melanoma?

Abstract

Adrenal masses vary in importance from being incidental findings of no clinical significance to having sinister consequences through malignancy. The importance in integrating the clinical history, biochemical findings and results of modern imaging techniques is illustrated in this case. CASE HISTORYA man of 70 presented to his general practitioner with a 2month history of weight loss, anorexia, nausea and abdominal pains. Past medical history included pharyngeal pouch and excision of a malignant melanoma from his left shoulder 7 years previously. The previous melanoma was a 1 cm maximum diameter superficial spreading type of malignant melanoma showing invasion of the epidermis and superficial dermis with a maximum depth of 0.6 mm. The resection margins were clear. The patient had shown no clinical evidence of local recurrence or axillary lymphadenopathy at 6-monthly reviews and was discharged after 5 years of follow-up according to the prevalent protocol.Physical examination was unremarkable except for a scar on his shoulder. Routine blood tests and chest radiograph were normal. He was referred to his local hospital where he was seen a month later and was found to be hypertensive, with a blood pressure of 190/96 mmHg, for which he was commenced on lisinopril. Abdominal ultrasound and subsequent computerized tomography scanning (Figure 1) revealed enlargement of both adrenal glands, reported as 'probably benign'. In view of the hypertension and adrenal masses, urinary catecholamines were measured. 24-hour urinary noradrenaline (254 nmol/24 h) and adrenaline (21 nmol/24 h) excretion were normal, but 24-hour urinary dopamine was grossly elevated at 18 783 nmol (normal 53194 nmol). He was referred to the tertiary centre (3 months after his initial presentation to his general practitioner) for further investigation of possible bilateral dopamine secreting phaeochromocytoma.He was seen the next day. By now he was generally unwell with nausea and vomiting, and had lost 20 kg in weight since the start of his illness. He had no palpitations, sweats or fainting. He looked cachectic and tanned. There was no palpable lymphadenopathy. Blood pressure was 159/85 mmHg. Large masses were palpable in both abdominal flanks. Adrenal insufficiency was suspected and after performance of a short Synacthen test (baseline cortisol 296 nmol/L, 30-min cortisol 268 nmol/L) he was started on hydrocortisone. His symptoms improved dramatically with increases in appetite and weight, and rapid resolution of the nausea and vomiting.After correction of his hypoadrenalism, routine blood tests were normal. Plasma noradrenaline (2.79 nmol/L; normal range 0.59-5.33 nmol/L) and adrenaline (50.055 nmol/L; normal range 50.82 nmol/L) were not elevated, 153 Figure 2 Melanuria-a specimen of the patient's urine that had been left standing. The dark colour is due to the oxidation of melanogens in the urine.

Adrenal malignant melanoma masquerading as a pheochromocytoma in a patient with a history of a multifocal papillary and medullary thyroid carcinoma

“…Generally, on CT scan, large pheochromocytomas (>2-3cm) can be inhomogeneous with areas of hemorrhage and low attenuation necrosis. On MRI, after contrast administration, pheochromocytomas enhance avidly and have a prolonged washout phase, at least at their viable areas, while necrotic parts of the tumor do not enhance (27). Adrenal metastases are usually presented with similar imaging features on MRI, as well (28).…”

“…Pheochromocytomas sometimes express somatostatin receptors, but most of the times benign tumors are octreotide-negative (66%-75%), even though they appear MIBG-positive. However, octreotide scintigraphy has 90% sensitivity in detecting malignant-metastatic pheochromocytomas and paragangliomas (27,29). Similarly, octreotide scintigraphy, showed a sensitivity and specificity of 87% and 94% respectively, for diagnosing metastases from malignant melanoma (30).…”