Ectopic Adrenocorticotropic Hormone-Secreting Pituitary Adenoma in the Clivus Region: A Case Report

Abstract

Ectopic pituitary adenoma (EPA) is a pituitary adenoma unrelated to the intrasellar component and is an extremely rare disease. EPA resembles typical pituitary adenomas in morphology, immunohistochemistry, and hormonal activity, and it may present with specific or non-specific endocrine manifestations. Here, we report a rare case of ectopic adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma in the clival region. Only three patients with ACTH-secreting pituitary adenomas occurring in the clivus have been previously reported, and the present case was diagnosed as a clivus-ectopic ACTH-secreting pituitary macroadenoma. Thus, in addition to the more common organs, such as the lung, thymus, and pancreas, in the diagnosis of ectopic ACTH syndrome, special attention should be paid to the extremely rare ectopic ACTH-secreting pituitary adenoma of the clivus region.

Keywords: Cushing’s syndrome; adrenocorticotropic hormone; clivus; ectopic pituitary adenoma; endocrine.

Figure 1

(A) MR T1+T2 scan (transverse view). MR T1 scan (left) shows the soft tissue mass of the occipital clivus (white arrow), and MR T2 scan (right) shows that the right internal carotid artery, cavernous sinus, and tumor are within close proximity to each other (white arrow). (B) MR T1 enhanced scan (sagittal view) shows clear demarcation between normal pituitary gland and mass (white arrow). (C) MR T2 scan (sagittal view) shows that the pituitary fossa is normally present (white arrow). (D) CT (sagittal view) shows bony destruction of dorsum sellae, clivus, and sphenoid sinus by mass (white arrow).

Figure 2

Pathological diagnosis of (clivus) ectopic pituitary adenoma. (A) Pituitary adenoma revealing a trabecular and nested structure revealing vascular invasion (hematoxylin and eosin (HE) stain, 200x) composed of two distinct types of cells. (B) ACTH expression in the EPA (200x, ACTH-antibody, Dako).