Eric K. Outwater, MD . Donald G. Mitchell, MD . Ira G. Rubenfeld, MD
Correction to a Previously Published Case: Recurrence of Invasive Adrenocortical Tumor after Excision of Atypical Adenoma1
A 74-year-old woman had hyperaldo- steronemia and an adrenal adenoma that showed no evidence of lipid on in-phase and opposed-phase gradient- echo magnetic resonance (MR) images. MR images obtained 4 years after resec- tion of the mass showed large masses of invasive tumor in the resection site, with small foci of lipid, and biopsy re- sults confirmed the presence of an ad- renocortical tumor.
Index terms: Adrenal gland, CT, 86.1211 . Adrenal gland, MR, 86.121411, 86.121412 · Ad- renal gland, neoplasms, 86.317, 86.324
Radiology 1997; 202:531-532
T HE detection of lipid in benign adre- nocortical nodules and adrenal adenomas with computed tomography (CT) or magnetic resonance (MR) imag- ing is an established technique for diag- nosing such lesions noninvasively (1-6). In an earlier description of chemical shift MR imaging for diagnosis of be- nign adrenocortical masses (7), one of us (D.G.M.) found that 26 of 27 benign cortical masses showed a loss of signal intensity on opposed-phase gradient- echo or fat-saturation spin-echo T1- weighted MR images. The one adrenal mass that did not show this loss of sig- nal intensity was excised and found to be an atypical adenoma without evi- dence of malignancy. The histologic re- sults of this tumor were presented (7). The benign adrenal lesion, which did not contain lipid, was actually a low- grade adrenocortical carcinoma, al- though it was not recognized histologi- cally as such at the time. We present this case report to correct the results pre- sented in the earlier article and to ana- lyze some of the imaging features of these tumors.
CASE REPORT
A 74-year-old woman was evaluated with MR imaging for symptoms of aldo-
1 From the Departments of Radiology (E.K.O., D.G.M.) and Medicine (I.G.R.), Thomas Jefferson University Hospital, 132 S 10th St, 10th Floor, Main Bldg, Philadelphia, Pa 19107-5244. Re- ceived September 16, 1996; accepted September
23. Address reprint requests to E.K.O. € RSNA, 1997
sterone excess. Her aldosterone level was 185 ng/dL (5,130 pmol/L), and her blood pressure was 200/110 mm Hg. MR imaging at 1.5 T showed two adrenal masses in the left adrenal gland. One mass showed typical loss of signal in- tensity on opposed-phase images, which is characteristic for adrenal ad- enoma. The second, larger mass (4.5 x 2.4 cm) showed higher signal intensity on T2-weighted images and no appar- ent loss of signal intensity on opposed- phase images (Figure). The adrenal masses were excised. The smaller mass was consistent with its imaging features in that it showed abundant lipid within the adrenal adenoma. The second mass showed atypical but benign cells that were small, tightly packed, and devoid of substantial lipid droplets. There was abundant interstitial space between the cells.
The patient underwent MR imaging 2 years later for recurrent symptoms of
aldosterone excess (blood pressure, 193/96 mm Hg; potassium ion level, 2.5 mmol/L). The MR images showed a small amount of tissue within the adre- nalectomy bed and small nodules adja- cent to the renal cortex and in the para- spinal muscles along the plane of the incision for left adrenalectomy (Figure, part d). The patient underwent imaging 21/2 years later when her blood pressure was 230/110 mm Hg. Repeat MR imag- ing at this time showed large masses at the site of the previous three nodules: in the adrenalectomy bed, posterior to the kidney, and in the left paraspinal muscle (Figure, part e). Small foci of relative signal intensity loss on op- posed-phase images, consistent with lipid, were identified within the mass. Biopsy resulted in benign histologic findings identical to those of the origi- nal tumor, with few mitoses. She under- went chemotherapy.
Benign adrenocortical nodules or ad-
a.
b.
c.
M
M
d.
e.
Growth of a low-grade left adrenal tumor. T1-weighted (a) in-phase (repetition time msec/ echo time msec, 115/4.2; flip angle, 90°) and (b) opposed-phase (72/2.4; flip angle, 90°) spoiled gradient-echo images obtained at initial presentation show a mass (arrow) with no evidence of lipid (ie, no loss of signal intensity relative to the spleen or kidney) in the left adrenal gland. (c) T2-weighted fast spin-echo image (5,383/91) obtained at initial presentation reveals high signal intensity in the mass (arrow). (d) T2-weighted fast spin-echo image (5,000/102) obtained 2 years later after resection of the mass shows a high-signal-intensity nodule (arrow) in the paraspinal muscle along the incision site (dotted line). (e) Gadolinium-enhanced fat-saturated gradient-echo image (120/2.3; flip angle, 90°) obtained 21/2 years later shows enhancing masses (M) in the paraspinal muscle and adjacent to the kidney. Biopsy showed tumor cells identical to those of the original histologic examination.
enomas contain small amounts of lipid. CT or MR imaging can demonstrate lipid in most nodules or adenomas, but there is a group of these benign nodules that cannot be accurately characterized as lipid containing with MR imaging or CT (1-4,6). No systematic study has been performed to determine whether the nodules that show no lipid have any particular clinical relevance. Occa- sional adrenocorticocarcinomas may show foci of lipid on opposed-phase MR images (8,9). In our patient, the tu- mor demonstrated more aggressive be- havior than a benign adenoma. Repeat review of the material with the patholo- gist showed no change in the original interpretation: atypical but benign cells.
DISCUSSION
This case report is presented to revise earlier data that showed this tumor to
be a benign adenoma. Second, it reem- phasizes the difficulty of differentiating some adenomas from adrenocortical carcinomas on the basis of either histo- logic or MR criteria.
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