Computed Tomography and Magnetic Resonance Images of Adrenocortical Oncocytoma Cases
In May 2012, a 10-yr-old girl presented to our outpatient clinic for the evaluation of precocious puberty, which was diagnosed elsewhere. The patient reported no specific past history and no specific clinical symptoms, such as flushing, fever, or abdominal pain. A physical examination revealed elevated breast buds and the start of menstruation. The results of laboratory evaluations showed increased levels of androstenedione (23.1, normal range: 1.7-2.7 ng/dL) and estradiol (46.61, normal range: 0.2-3.0 ng/mL). Testosterone was mildly increased (1.64, normal range: 0.03-0.68 ng/mL), cortisol was slightly decreased (5.49, normal range: 6.2-19.4 µg/dL), and normal ranges of follicle stimulating hormone, luteinizing hormone, and adrenocorticotropic hormone were observed. There were no chromosomal anomalies. Abdominal CT scans detected a well-circumscribed, oval-shaped, 6-cm mass in the left adrenal gland, located superior to the left kidney, which demonstrated stippled calcifications on a precontrast scan. After the injection of a nonionic contrast medium (Omnipaque 350®, GE Healthcare, USA), volume of 100 mL of contrast medium was injected at a rate of 3 mL/s via an antecubital vein, heterogeneous well enhancement was visualized during the 1-min delayed scan, and enhancement washout was demonstrated on the 15-min delayed scan (). The CT Hounsfield unit (HU) was 40 HU on precontrast, 140 HU at 1 min, and 70 HU at 15 min. The absolute washout value ([Enhanced CT HU-Delayed CT HU]/[Enhanced CT HU-Unenhanced CT HU]×100) was approximately 70% (a value of more than 60% indicates adrenal adenoma), and the relative washout value ([Enhanced CT HU-Delayed CT HU]/Enhanced CT HU×100) was 50% (a value of more than 40% indicates adrenal adenoma) (). Initially we thought that functional adrenal adenoma should be included in the differential diagnosis. A left adrenalectomy was performed. During the operation, there was no evidence of hypertension associated with palpation of the mass or direct invasion to the surrounding organs. The tumor was approximately 6×4 cm, well-encapsulated and dark brown in color (). The tumor consisted of multiple small hemorrhagic vascular lakes with old blood. The microscopic examination revealed that the neoplasm consisted of polygonal cells with abundant eosinophilic cells and granular cytoplasm. Nuclear cellular atypia with enlarged nuclei were identified (×200, ×400 High Power Field [HPF], hematoxylin and eosin [H&E], ). An electron microscopic study was performed, and electron-dense inclusion and closely packed mitochondria with Golgi complex were found (×400 HPF, ). Thus, we concluded that the final diagnosis in this case was adrenocortical oncocytoma. The patient had an uneventful postoperative course and was doing well one year after surgery without new lesions.