CASE REPORT Successful treatment of Cushing’s disease caused by ectopic intracavernous microadenoma Mitsuteru Koizumi Æ Takeshi Usui Æ Shozo Yamada Æ Ichiro Fujisawa Æ Tsunehisa Tsuru Æ Kazutaka Nanba Æ Hanae Hagiwara Æ Takashi Kimura Æ Tamiko Tamanaha Æ Tetsuya Tagami Æ Mitsuhide Naruse Æ Akira Shimatsu Published online: 3 December 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Adrenocorticotropic hormone (ACTH)-secret- ing pituitary adenomas are sometimes difficult to visualize, even with high-quality magnetic resonance imaging, due to their small size and variable location. Sampling the cav- ernous or inferior petrosal sinus is helpful for confirming the central origin of a tumor, but ectopic corticotroph adenomas in the paraseller region also typically exhibit a high central/peripheral plasma ACTH ratio. We experi- enced an extremely rare case of Cushing’s disease caused by an ACTH-secreting microadenoma located entirely inside the left cavernous sinus attached to the medial wall (ectopic pituitary adenoma) that was not visible by pre- operative MRI. In this case, the microadenoma was completely removed and an endocrinologic cure was achieved. This case reveals that in addition to meticulous sectioning of the pituitary gland, bilateral periglandular inspection with visualization of the medial wall of the cavernous sinus and of the diaphragm should always be performed to detect ectopic parasellar microadenomas when no adenoma is visible by preoperative MRI. Keywords Cushing’s disease Á Ectopic Á Intracavernous sinus Á Surgery Introduction Guidelines for diagnosing Cushing’s syndrome were recently published [1]. Endocrinologic findings should be followed by sellar magnetic resonance imaging (MRI) with gadolinium for anatomic localization of the tumor. If no tumor is evident on MRI, inferior petrosal sinus sampling or cavernous sinus sampling with corticotropin-releasing hormone (CRH) stimulation may unequivocally confirm the presence of a pituitary tumor [2]. Occasionally, how- ever, the pituitary tumor cannot be identified during surgery or hypercortisolism is not restored even after total hypophysectomy, despite endocrinologic and inferior petrosal sinus sampling or cavernous sinus sampling data indicating the presence of a tumor in the pituitary gland [3]. There are several possible reasons for these findings; misdiagnosis, presence of a very small pituitary tumor, lack of surgical experience [4], corticotroph hyperplasia [5–7], and presence of an extra-pituitary parasellar adenoma [4, 8–10]. We report here in a case of ectopic adrenocortico- tropin (ACTH)-secreting pituitary adenoma located on the intracavernous sinus that was not visualized by preopera- tive MRI. After surgery, the clinical symptoms of Cushing disease disappeared. M. Koizumi Á T. Usui Á T. Tsuru Á K. Nanba Á H. Hagiwara Á T. Kimura Á T. Tamanaha Á T. Tagami Á M. Naruse Á A. Shimatsu Department of Endocrinology and Metabolism, National Hospital Organization Kyoto Medical Center, Mukaihata-cho Fukakusa Fushimi-ku, Kyoto 612-8555, Japan T. Usui (&) Á T. Tagami Á M. Naruse Á A. Shimatsu Clinical Research Institute Center for Endocrine and Metabolic Diseases, National Hospital Organization Kyoto Medical Center, Mukaihata-cho Fukakusa Fushimi-ku, Kyoto 612-8555, Japan e-mail: tusui@kyotolan.hosp.go.jp; tusui@kuhp.kyoto-u.ac.jp S. Yamada Department of Hypothalamic & Pituitary Surgery, Toranomon Hospital, Tokyo, Japan I. Fujisawa Department of Radiology, Kishiwada City Hospital, Kishiwada, Japan 123 Pituitary (2011) 14:295–298 DOI 10.1007/s11102-008-0156-9