Zaman Shamaila, Patel Bijal, Glynne Paul, Vanderpump Mark, Alsafi Ali, Khan Sairah, Flora Rashpal, Palazzo Fausto, Wernig Florian
Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK.
The Physicians' Clinic, London, UK.
Endocrinol Diabetes Metab Case Rep. 2020 Mar 13;2020. doi: 10.1530/EDM-20-0011.
Ectopic adrenocorticotropic hormone (ACTH) production is an uncommon cause of Cushing's syndrome and, rarely, the source can be a phaeochromocytoma. A 55-year-old man presented following an episode of presumed gastroenteritis with vomiting and general malaise. Further episodes of diarrhoea, joint pains and palpitations followed. On examination, he was hypertensive with no clinical features to suggest hypercortisolaemia. He was subsequently found to have raised plasma normetanephrines of 3.98 nmol/L (NR <0.71) and metanephrines of 0.69 nmol/L (NR <0.36). An adrenal CT showed a 3.8 cm right adrenal nodule, which was not MIBG-avid but was clinically and biochemically consistent with a phaeochromocytoma. He was started on alpha blockade and referred for right adrenalectomy. Four weeks later, on the day of admission for adrenalectomy, profound hypokalaemia was noted (serum potassium 2.0 mmol/L) with non-specific ST-segment ECG changes. He was also diagnosed with new-onset diabetes mellitus (capillary blood glucose of 28 mmol/L). He reported to have gained weight and his skin had become darker over the course of the last 4 weeks. Given these findings, he underwent overnight dexamethasone suppression testing, which showed a non-suppressed serum cortisol of 1099 nmol/L. Baseline serum ACTH was 273 ng/L. A preliminary diagnosis of ectopic ACTH secretion from the known right-sided phaeochromocytoma was made and he was started on metyrapone and insulin. Surgery was postponed for 4 weeks. Following uncomplicated laparoscopic adrenalectomy, the patient recovered with full resolution of symptoms.
Phaeochromocytomas are a rare source of ectopic ACTH secretion. A high clinical index of suspicion is therefore required to make the diagnosis. Ectopic ACTH secretion from a phaeochromocytoma can rapidly progress to severe Cushing's syndrome, thus complicating tumour removal. Removal of the primary tumour often leads to full recovery. The limited literature suggests that the presence of ectopic Cushing's syndrome does not appear to have any long-term prognostic implications.
异位促肾上腺皮质激素（ACTH）分泌是库欣综合征的一种罕见病因，而其来源极少可能是嗜铬细胞瘤。一名55岁男性在经历了一次疑似肠胃炎发作，伴有呕吐和全身不适后前来就诊。随后又出现腹泻、关节疼痛和心悸发作。检查时，他患有高血压，但无提示皮质醇增多症的临床特征。随后发现他的血浆去甲肾上腺素升高至3.98 nmol/L（正常范围<0.71），肾上腺素为0.69 nmol/L（正常范围<0.36）。肾上腺CT显示右侧肾上腺有一个3.8 cm的结节，该结节不摄取间碘苄胍（MIBG），但在临床和生化方面与嗜铬细胞瘤相符。他开始接受α受体阻滞剂治疗，并被转诊进行右侧肾上腺切除术。四周后，在肾上腺切除术入院当天，发现严重低钾血症（血清钾2.0 mmol/L），伴有非特异性心电图ST段改变。他还被诊断为新发糖尿病（毛细血管血糖28 mmol/L）。他报告在过去4周内体重增加，皮肤变黑。鉴于这些发现，他接受了过夜地塞米松抑制试验，结果显示血清皮质醇未被抑制，为1099 nmol/L。基础血清ACTH为273 ng/L。初步诊断为已知右侧嗜铬细胞瘤分泌异位ACTH，于是开始使用甲吡酮和胰岛素治疗。手术推迟4周。在进行了无并发症的腹腔镜肾上腺切除术后，患者康复，症状完全缓解。
嗜铬细胞瘤是异位ACTH分泌的罕见来源。因此，诊断需要高度的临床怀疑指数。嗜铬细胞瘤分泌的异位ACTH可迅速发展为严重的库欣综合征，从而使肿瘤切除复杂化。切除原发肿瘤通常会导致完全康复。有限的文献表明，异位库欣综合征的存在似乎没有任何长期预后影响。
