RADIOLOGICAL OBSERVATION OF THE GROWTH OF NONFUNCTIONING ADRENAL TUMORS

Abstract

42 RADIOLOGICAL OBSERVATION OF THE GROWTH OF NONFUNCTIONING ADRENAL TUMORS Gaku Tamaki*, Yuji Kato, Tatsuhiko Kura, Yuji Saga, Hidehiro Kakizaki. Asahikawa, Japan. INTRODUCTION AND OBJECTIVE: Improvement in abdominal imaging techniques has increased the detection of adrenal incidentaloma. When the adrenal mass is less than 4cm in diameter and nonfunctioning, usually it can be followed with a regular radiological examination. However, if the tumor growth is observed, we must decide whether it should be removed with the possibility of malignant potential in mind. To elucidate the frequency and velocity of tumor growth among nonfunctioning adrenal masses, we performed a retrospective analysis of chronological changes in diameter of clinically nonfunctioning adrenal tumors. METHODS: From January 2000, 138 patients with adrenal mass visited our hospital. All the patients underwent a diagnostic workup that included computed tomography (CT) and endocrinological function of the adrenal gland. CT was taken twice or more in 47 patients (23 males and 24 females) with nonfunctioning adrenal tumor. These 47 patients (mean age 62.7 years) had 55 tumors (unilateral in 39 and bilateral in 8) and were followed for 1-116 months (median 20.8 months). We examined chronological changes in tumor diameter and the velocity of tumor growth by CT. RESULTS: Clinical diagnosis of 55 tumors was adenoma in 44, metastatic tumor in 5, cyst or hematoma in 4, myelolipoma and uncertain nature in one each. Among the 55 tumors, 7 (12.7%) showed 5 mm or greater increase in diameter and the velocity of tumor growth in the 7 tumors was 39.6 mm per year. Adrenalectomy was performed for 2 of the 7 tumors with growth and pathological diagnosis was cyst and gastrointestinal stromal tumor (GIST) of the stomach in one each. Suspected diagnosis of the other 5 tumors with growth was metastatic tumor in 2, adenoma in 2 and cyst in 1. Four of the 55 tumors showed 5 mm or greater decrease in diameter and the remaining 44 tumors showed no change in diameter. Suspected diagnosis of the 5 tumors with regression was adenoma in 3 and cyst and hematoma in one each. If only nonfunctioning adenoma is taken into account, the frequency and velocity of tumor growth was 4.5% (2/44) and 7.3mm per year, respectively. Regarding adrenal tumors other than adenoma, the frequency and velocity of tumor growth was 45.5% (5/11) and 52.5mm per year, respectively. CONCLUSIONS: When a diagnostic workup suggests nonfunctioning adrenal adenoma, the frequency of tumor growth is very low and thus repeating imaging studies at a short interval is not warranted. However, if the radiological feature of adrenal adenoma is lacking, close followup is mandatory to detect tumor growth and to treat without undue delay.