title: A black adrenal adenoma difficult to be differentiated from a malignant adrenal tumor by CT, MRI, scintigraphy and FDG PET/CT examinations.
abstract: Black adrenal adenoma (BAA) is an adrenal adenoma which contains lipofuscin and has a black or brown appearance. Preoperative diagnosis of BAA is difficult because it is diagnosed by pathologic findings. We report a case of an incidentally discovered non-hyperfunctioning BAA in the left adrenal gland of a 58-year-old man. It showed an oval lipid-poor mass, 3 cm × 2 cm in size on computed tomography (CT) and magnetic resonance imaging (MRI), no avid uptake of (131)I-norcholesterol and (123)I-meta-iodobenzylguanidine (MIBG) on scintigraphy, and intense avid uptake of (18)F-fluorodeoxyglucose (FDG) on positron emission tomography-CT (PET/CT). FDG PET/CT showed that it was a hypermetabolic lesion, more intense than the activity of the liver, and the maximum standardized uptake value was 5.6 on 1-h early imaging and 8.3 on 2-h delayed imaging, suggesting a malignant tumor. BAA is a clinically rare benign adrenal adenoma, but it should be kept in mind that BAA may exhibit false-positive results for malignancy or inconclusive results for benignity with modern imaging modalities including CT, MRI, adrenal scintigraphy with radiolabelled cholesterol and radiolabelled MIBG, and FDG-PET like this case.
authors.affiliation: Department of Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan. toyo.nakajo@dolphin.ocn.ne.jp
authors.forename: Masatoyo
authors.initials: M
authors.lastname: Nakajo
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nakajo
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Kajiya
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tani
authors.forename: Masashi
authors.initials: M
authors.lastname: Tsuruta
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sugita
authors.forename: Shunsaku
authors.initials: S
authors.lastname: Fushitani
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Umekita
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D003937:Diagnosis, Differential; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18