1289268

Differential Diagnosis of Adrenal Tumour and Upper Pole Renal Tumour by I-131 Cholesterol Adrenocortical Scintigraphy

M. TAKEDA, T. TORII, T. NISHIYAMA, Y. KATAYAMA, T. TSUTSUI, T. KOMEYAMA, M. TAKEDA,* M. KIMURA **

Department of Urology, Niigata University School of Medicine; * Section of Urology, Koseiren Nagaoka Chuo Hospital; ** Department of Radiology, Niigata University School of Medicine, Japan

(Accepted April 4, 1992)

A 27-year-old housewife with right hypochondralgia was admitted for treatment of a huge right adrenal or upper pole renal tumour. The tumour measured 10x 8x 8 cm and was hypovascular. The main blood supply derived from the right adrenal artery which originated from the abdominal aorta just proximal to the right renal artery. Although several diagnostic imaging studies suggested that the tumour arose from the right adrenal gland, the bilateral adrenal glands were equally visualized on I-131 cholesterol adrenocortical scintigraphy. After surgery and pathological examination, the tumour proved to be a renal cell cancer, while the right adrenal gland was intact. This case demonstrates that adrenocortical scintigraphy is useful in the differentiation of adrenal and renal tumours when a large tumour occupies the upper pole of the kidney or adrenal gland.

Introduction

Despite continuing improvements in computed tomography (CT), ultra- sonography (US) and magnetic resonance imaging (MRI), the differentiation of ad- renal from upper pole renal tumour is still difficult. We report a case in which I-131 cholesterol adrenocortical scintigraphy was more useful in differentiating renal from adrenal tumour than CT and angiography, and discuss methods used in the differentiation of these lesions.

Case report

A 27-year-old housewife presented with right hypochondralgia and was admitted for treatment of a right renal or adrenal tumour which had been de- tected by US at the outpatient clinic. On physical examination, a large soft mass was palpated in the right hypochondral region. Blood pressure, blood examina- tion, blood chemistry, serum cortisol, serum aldosterone and urinary catechol- amine were all within normal limits. Abdominal US showed a large multicystic 10×8×8 cm mass at the right upper pole of the kidney. CT showed similar find-

Fig. 1. Abdominal CT with contrast enhancement. A large multicystic tumour (white arrow) at the upper pole of the kidney or the right adrenal gland, compressing the right lobe of the liver

ings as well as the possibility of direct invasion to the liver (Fig. 1). The normal right adrenal gland could not be visualized on CT and US. Angiography revealed that the tumour was hypovascular and its vessels derived mainly from the dia- phragmatic artery and small adrenal artery which originated from the abdominal aorta slightly proximal to the right renal artery (Fig. 2). On I-131 cholesterol adrenocortical scintigraphy, the bilateral adrenal glands were equally visualized (Fig. 3), suggesting that the tumour was unlikely to be of adrenal origin. At surgery, the right kidney encapsulated with the large tumour measured 18 x 12 x 12 cm, and weighed 1080 g, and could be easily separated from the liver (Fig. 4). The right adrenal gland was normal. Histopathologic examination revealed that the tumour was a renal cell carcinoma. Postoperatively, the patient did well and was discharged 2 weeks after operation.

Discussion

Recent improvements in imaging diagnosis have made possible new diag- nostic and therapeutic strategies for tumours of the kidneys, adrenal glands and retroperitoneum [1]. The new non-invasive imaging techniques, such as US, CT and MRI, can eliminate the need for angiography to diagnose renal masses. In spite of such improvements, however, it is still almost impossible to differentiate adrenal tumours from large hypovascular upper pole renal tumours clearly by US, CT and even angiography [2, 3]. Little information is available about the

Fig. 2a. Abdominal aortography. The right kidney deviates downward (white arrow) due to compression by the tumour. The right renal artery only slightly fed the tumour

Fig. 2b. Right adrenal arteriography. The upper and median regions of the tumour are hyper- vascular, and the tumour is fed mainly by the right adrenal artery

Fig. 3. Posterior view of I-131 cholesterol adrenocortical scintigraphy 2 days post-injection without dexamethasone suppression

Fig. 4. Cut surface of the tumour (arrow) and the right kidney (arrow head), commonly encapsulated

efficacy of adrenocortical scintigraphy in differentiating these lesions. Although I-131 adrenocortical scintigraphy was useful in our case, two possible exceptions can be entertained. One is non-functioning adrenal cancer whose blood supply is derived mainly from the ipsilateral renal artery. The other is upper pole renal cell cancer which has directly invaded or metastasized to the ipsilateral adrenal gland. Although the usefulness of MRI in this area has been increasing rapidly, it is still almost impossible to diagnose the origin of such tumours by MRI even when using various pulse sequences and contrast media.

Acknowledgement

We thank the staff of the Section of Radiology, Nagaoka Chuo Hospital, and Prof. S. Sato for supervision of this report.

References

1. Davidson, A. J., Hartman, D. S .: Imaging strategies for tumors of the kidney, adrenal gland and retroperitoneum. CA-A Can. J. Clin., 37, 151 (1987).

2. Shrago, G. G., Mckinnon, C. M., Clark, R .: Adrenal tumors simulating intrarenal lesions. Am. J. Roentgenol., 121, 518 (1974).

3. Fritzsche, P., Anderson, C., Cahil, P .: Vascular specificity in differentiating adrenal carci- noma from renal cell carcinoma. Radiology, 125, 113 (1977).