TITLE:
Clear Discrepancy in Neurofibromin Expression between NF1 Pheochromocytoma Cells and Non-Tumorous Adrenal Medullary Cells
AUTHORS:
Koji Mikami, Yumiko Okuno, Masayoshi Zaitsu, Hiroki Tanaka, Koichi Sakazume, Akiko Tonooka, Toshimasa Uekusa, Takumi Takeuchi
KEYWORDS:
Pheochromocytoma, NF1, Neurofibromin
JOURNAL NAME:
Open Journal of Urology,
Vol.6 No.5,
May
20,
2016
ABSTRACT: Neurofibromatosis type 1 (NF1) is a common
inherited disorder with an autosomal dominant trait. We encountered an NF1
patient who showed adrenal pheochromocytoma, and analyzed expression of
neurofibromin in an excised specimen. A 54-year-old man showing multiple
neurofibromas and café-au-lait spots in the skin was pointed out to have a
right adrenal tumor by ultrasonography. Abdominal CT also revealed a right
adrenal tumor. He was diagnosed with neurofibromatosis type 1 with no family
history. Urine catecholamines, metanephrine, and normetanephrine levels were
elevated. MIBG scintigraphy showed positive right adrenal uptake, and so
pheochromocytoma was also diagnosed. The patient underwent laparoscopic right
adrenalectomy. The excised adrenal specimen of this patient was stained with
anti-neurofibromin polyclonal antibody. The NF1 pheochromocytoma was completely
negative for neurofibromin protein expression, while the NF1
non-pheochromocytomatous adrenal medulla was neurofibromin-positive in the
cytoplasm and nucleus. The clear discrepancy in neurofibromin expression
between pheochromocytoma cells and “normal” adrenal medullary cells of the
patient may well be explained by Knudson’s two-hit hypothesis.