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 tumor cells separated by fibrovascular stroma is a characteristic finding.

Pathophysiology

Mutations of the genes VHL, RET, NF1, SDHB, and SDHD are all known to cause familial pheochromocytoma. Traditionally pheochromocytoma known as the "10% tumor":

Bilateral disease is present in approximately 10% of patients
Approximately 10% of tumors are malignant
Approximately 10% are located in chromaffin tissue outside of the adrenal gland
Approximately 10% occur in childhood
Approximately 10% are familial
Approximately 10% recur after being resected
Approximately 10% patients do not have hypertension

Pheochromocytoma can occur in patients with multiple endocrine neoplasia (MEN 2 and MEN 3), also patients with Von Hippel Lindau (VHL ) may develop pheocromocytoma.

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 tumor cells containing eosinophilic cytoplasm separated by fibrovascular stroma.