嗜鉻細胞瘤，尤其是位於腎上腺以外者，可能因未被查覺而造成致命的併發症，由於異常的位置及不明顯的症狀、位於腎上腺以外的嗜鉻細胞瘤很容易被忽略。我們回顧性探討五十八例嗜鉻細胞瘤，其中四十五例其腫瘤位於腎上腺內（Group A），十三例之腫瘤位於腎上腺以外（Group B）。我們比較兩組病患之臨床資料，包括年齡、性別、症狀，生化資料，發生惡性之情形，去氧核酐酸流動細胞圖形儀，定位方法等，除了Group A 的男性比率較Group B高以外，其餘的臨床資料在兩組之間，並無明顯差別，MIBG Scan 及 CT scan 是定位腎上腺外鉻細胞瘤之最佳方法，高度的警覺性是診斷腎上腺外嗜鉻細胞瘤之最重要因素，這些腫瘤和腎上腺嗜鉻細胞瘤一可能轉變成惡性，長期的追蹤是必須的。

Pheocromocytomas, especially extra-adrenal lesions, can potentially cause lethal complications if they are not recognized. Because of possible unusual locations and lack of classical symptoms or signs, extra-adrenal pheochromocytomas may be easily neglected. A retrospective review of 58 cases of pheochromocytomas showed that 45 cases were adrenal lesions (Group A) and 13 cases were extra-adrenal lesions (Group B). Clinical parameters, e.g., age, sex, symptoms or signs, biochemical data, incidence of malignancy, DNA flow cytometric studies, localization methods were compared. In Group A, the male sex seemed to be more dominant than in Group B. Other clinical parameters were quite compatible in both groups. There was no difference in the incidence of malignancy or results of DNA flow cytometric studies between the groups. Radioactive iodine-labeled metaiodobenzyl-guanidine scan and computed tomography scan seemed to be the best localization methods. With improvement in diagnostic modalities, hagh index of suspicion is still the key in diagnosing extra-adrenal pheochromocytomas. As in their adrenal counterparts, malignanc is possible. Long-term follow-up for these extra-adrenal lesions is essential.