CLINICAL IMAGE
Adrenocortical carcinoma mimicking pheochromocytoma on iodine 123-labeled metaiodobenzylguanidine scintigraphy
Karolina M. Nowak1, Agnieszka Łebek-Szatańska1, Radosław Samsel2, Katarzyna Roszkowska-Purska3, Jarosław B. Ćwikła4, Lucyna Papierska1
1 Department of Endocrinology, Centre of Postgraduate Medical Education, Bielański Hospital, Warsaw, Poland
2 Division of Surgery, Department of Oncology, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland
3 Department of Pathology, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland
4 Department of Cardiology and Cardiac Surgery, School of Medicine, University of Warmia and Mazury, Olsztyn, Poland
A 39-year-old man with decompensated hyper- tension of up to 190/100 mm Hg was admitted to our department of endocrinology due to bilat- eral adrenal tumors revealed by ultrasonography and computed tomography (CT) of the abdomen. Noncontrast attenuation of the 63-mm left ad- renal tumor was 35 HU, and its absolute (APW) and relative (RPW) percentage washouts at de- layed contrast-enhanced CT (delay, 10 min) were 60% and 30%, respectively, while for the small- er 23-mm right adrenal tumor-98% and 77%, respectively. Chemical-shift magnetic resonance imaging (MRI) classified the left adrenal tumor as nonadenoma, as no signal loss occurred in the out-of-phase sequence (FIGURE 1A and 1B). Hypercortisolism and hyperaldosteronism were excluded, but the urinary levels of methoxycat- echolamines were 916 µg/24 h and 953 µg/24 h and remained in the upper limit of normal (up to 1000 µg/24 h). Iodine 123-labeled metaiodoben- zylguanidine (123I-MIBG) scintigraphy was car- ried out 6 hours after the patient had been given
a 380-MBq intravenous bolus injection of the ra- diotracer. It involved whole-body scanning com- plemented by single-photon emission CT (SPECT) centered on the lower part of the head, abdomen, and pelvis. The examination was performed with the E.cam imaging equipment (Symbia E SPECT gamma camera, Siemens Healthineers, Hoffman Estates, Illinois, United States) and showed an in- creased heterogeneous uptake in the left adrenal gland (FIGURE 1C). Somatostatin-receptor scintig- raphy with 630 MBq of technetium 99m-labeled hydrazinonicotinyl-Tyr3-octreotide gave similar results (FIGURE 1D).
Based on imaging and biochemical evaluation, a suspicion of pheochromocytoma (PCC) was raised and the patient underwent a surgery af- ter 2 weeks of a-blocker intake. After that, the pa- thology report, verified by 2 well-trained pathol- ogists, revealed a 71-mm adrenocortical carcino- ma (ACC), which stained negative for chromo- granin. Additional staining showed type 2 and 5 somatostatin receptors. Currently, 2 years after
Correspondence to: Karolina M. Nowak, MD, Department of Endocrinology, Centre of Postgraduate Medical
Education, Bielański Hospital, ul. Cegłowska 80, 01-809 Warszawa, Poland, phone: +48 22569 05 29, email: karolina.brodowska@gmail.com
Received: July 22, 2019.
Revision accepted: August 27, 2019.
Published online: August 30, 2019.
Pol Arch Intern Med. 2019; 129 (11): 822-823
doi:10.20452/pamw.14958
Copyright by Medycyna Praktyczna, Kraków 2019
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the initial diagnosis, the patient remains on mi- totane treatment and has no signs of recurrence.
Scintigraphy is used in the diagnostic work- up of adrenal disorders and is especially helpful when the diagnosis cannot be determined by CT or MRI.1 In the presented case, the clinical and biochemical evaluation, high density on unen- hanced CT, normal APW on delayed contrast- -enhanced CT, and no lipids on MRI suggested PCC (approximately 25% of PCCs have a high APW and/ or RPW value).2 In clinical practice, functional imaging with 123I-MIBG can be use- ful in confirming the diagnosis of PCC.3 Radio- tracer uptake in chromaffin cells occurs through passive diffusion and norepinephrine transport- ers. The tracer is then accumulated in the secreto- ry granules of the cells via vesicular monoamine transporters.4 Although 123I-MIBG scintigraphy (with SPECT) has high specificity (95%-100%) and sensitivity (83%-100%), false-positive results do occasionally occur.3-5 Tumors that mimic PCC include adrenal adenoma, retroperitoneal angio- myolipoma, hemangioma, malignant lymphoma, hepatocellular carcinoma, and other neuroendo- crine tumors not derived from chromaffin cells, such as medullary thyroid carcinoma, carcinoid tumors, Merkel cell carcinoma, or ganglioneuro- ma. An increased MIBG uptake was also described in 2 cases of ACC.4,5 It is speculated that it may be caused by passive diffusion of the radiotracer due to increased blood flow, but the underlying mechanisms are still incompletely understood. Nevertheless, these are extremely rare cases and they do not discredit the usefulness of 123I-MIBG scintigraphy in diagnosing PCC. However, oth- er adrenal lesions should be considered if an in- creased heterogeneous or inadequate radiotrac- er uptake is detected due to a large tumor mass.
ARTICLE INFORMATION
CONFLICT OF INTEREST None declared.
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HOW TO CITE Nowak KM, Łebek-Szatańska A, Samsel R, et al. Adre- nocortical carcinoma mimicking pheochromocytoma on iodine 123-labeled metaiodobenzylguanidine scintigraphy. Pol Arch Intern Med. 2019; 129: 822- 823. doi:10.20452/pamw.14958
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