Pheochromocytoma pathophysiology

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]

Overview

On gross pathology pheochromocytoma appears as Multinodular, multicentric pattern of growth. On microscopic histopathological analysis nesting (Zellballen) pattern composed of well-defined clusters of tumour cells separated by fibrovascular stroma is a characteristic finding.

Pathophysiology

Traditionally it is known as the "10% tumor":

bilateral disease is present in approximately 10% of patients
approximately 10% of tumours are malignant
approximately 10% are located in chromaffin tissue outside of the adrenal gland
Approximately 10% arise in childhood
Approximately 10% are familial
Approximately 10% recur after being resected
Approximately 10% patients do not have hypertension (Campbell's Urology)These tumors can form a pattern with other endocrine gland cancers which is labeled multiple endocrine neoplasia (MEN). Pheochromocytoma may occur in patients with MEN 2 and MEN 3. VHL (Von Hippel Lindau) patients may also develop these tumors.

Tumor Location

In adults, 90% tumors are located unilaterally and are solitary, and 10% are located outside the adrenal gland. In children 50% are adrenal, while 25% are bilateral and 25% are extraadrenal. The common extradrenal locations are the abdomen, thorax and urinary bladder.

Gross Pathology

Multinodular, multicentric pattern of growth of pheochromocytoma may be seen.

Bilateral pheochromocytoma in MEN2. Gross image.

Microscopic Pathology

Pheochromocytoma typically demonstrate a nesting (Zellballen) pattern on microscopy. This pattern is composed of well-defined clusters of tumour cells containing eosinophilic cytoplasm separated by fibrovascular stroma.