Carcinoma-like nonfunctional pheochromocytoma in the right adrenal gland: A case report

Abstract

Evaluation of the malignant potential of a pheochromocytoma (PCC) remains controversial. PCC is regarded as a neuroendocrine tumor (NET), and the classification of NETs has gradually been defined over the last decade, particularly for gastroenteropancreatic NET. The present study describes a case of locally advanced, carcinoma-like, nonfunctional PCC, which may be regarded as neuroendocrine carcinoma (NEC) rather than a malignant PCC. A 72-year-old man was referred to Saitama Red Cross Hospital (Saitama, Japan), presenting with a 2-month history of right flank pain. Computed tomography revealed a right adrenal gland tumor, which measured 6.0 cm in diameter, invading the hilum of the right kidney, liver and inferior vena cava (IVC). Radical surgery was performed with en bloc resection of the right kidney, and adjacent parts of the liver and IVC. Immunohistochemical examination demonstrated that all of the resected tissues were positive for cytokeratin AE1/AE3, chromogranin A, synaptophysin, cluster of differentiation 56 and Ki-67, and the specimen had a Ki-67 index of 80%. A diagnosis of carcinoma-like PCC or NEC of the adrenal gland was confirmed. Reports of NEC of the adrenal gland are extremely rare in the literature, and classification of PCC as a NET has not yet been fully discussed. The present case may therefore contribute to the classification of NETs in the adrenal gland.

Keywords: Ki-67; adrenal gland neoplasms; malignant pheochromocytoma; neuroendocrine carcinoma; neuroendocrine tumor; pheochromocytoma.

Figure 1.

Abdominal contrast-enhanced computed tomography showing a right adrenal tumor (6.0 cm in diameter) (A) suspected of invading the adjacent liver, and (B) extending into the posterior of the inferior vena cava and the hilum of the right kidney.

Figure 2.

A histopathological diagnosis of neuroendocrine carcinoma of the adrenal gland was confirmed based on (A) H&E staining (magnification, ×20), and immunohistochemical staining positive for (B) chromogranin A (magnification, ×40), (C) synaptophysin (magnification, ×40) and (D) Ki-67 (magnification, ×40). H&E staining revealed that the polygonal tumor cells had a high nucleus-to-cytoplasm ratio with abundant nuclear chromatin, and were arranged in cord-like and alveolar patterns. The mitotic count was 27/10 high-power fields, while the Ki-67 index was 80%. H&E, hematoxylin and eosin.