Pigmented Pheochromocytoma: an Unusual Variant of a Common Tumor.

Pheochromocytoma is a neuroendocrine tumor arising from the adrenal medulla. A number of variants of pheochromocytoma are known; however, pigmented pheochromocytoma is extremely rare, with only few cases reported in literature. We report the cases of two patients with pigmented pheochromocytoma. Case 1 was a 28-year-old female who presented with complaints of breathlessness, palpitations, and anxiety for 5 years, which had worsened over the last 8 months. Computed tomography (CT) abdomen showed a right suprarenal mass. Case 2 was that of an 18-year-old girl who presented with similar complaints and was diagnosed with hypertension. CT abdomen showed bilateral adrenal masses. Urinary vanillyl mandelic acid was raised in both patients. Sections examined from all three tumors showed cells arranged in Zellballen pattern, separated by thin fibrovascular septae. Tumor cells showed moderate to marked nuclear pleomorphism in case 1. Mitoses were, however, not seen. There was no evidence of capsular or vascular invasion. Many of the tumor cells showed intracytoplasmic black pigment, which was positive for Fontana-Masson and was bleach-labile, confirming it as melanin. Hemosiderin deposition was also identified. Large areas of hemorrhagic necrosis were seen in case 1. Tumor cells were immunopositive for chromogranin and synaptophysin, while they were negative for HMB-45. Electron microscopy was performed. A final diagnosis of pigmented pheochromocytoma was rendered in both cases. Pigmented pheochromocytoma is a very rare tumor, which needs to be differentiated from other pigmented tumors like malignant melanoma of adrenal gland and pigmented adrenal adenoma. Histochemistry and immunohistochemistry help in making this distinction.