Melanoma of unknown primary origin presenting as a rapidly enlarging adrenal mass

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

OBJECTIVE

Adrenal masses usually represent benign and nonfunctional adrenal adenomas; however, primary or metastatic malignancy should also be considered. Discovery of an adrenal mass needs further evaluation in order to exclude malignancy and hormonal secretion. We present a rare case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma.

CASE REPORT

A 61-year-old male farmer was referred for evaluation of a mass in the right supraclavicular region and a left adrenal lesion. The patient had a history of a multifocal papillary and medullary thyroid carcinoma. Laboratory tests revealed increased 24hour urinary dopamine and also increased serum calcitonin and neuron specific enolase. A pathology report of the resected right supraclavicular mass and left adrenal showed a malignant melanoma.

CONCLUSION

This is a case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma. Although this case is very rare and there are rigid diagnostic criteria for the diagnosis of primary adrenal melanoma, it underlines the fact that the differential diagnosis of a dopamine secreting adrenal mass should include primary or metastatic malignant melanoma in order to determine the best diagnostic approach for the patient and select the most appropriate surgical management.

Metabolic and anatomic characteristics of benign and malignant adrenal masses on positron emission tomography/computed tomography: a review of literature

PET/CT with (18)F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal "incidentaloma" FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been 'indeterminately' categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.