診斷: 因為在central, rule in sarcoidosis, small cell lung cancer, squamous lung carcinoma, bronchial carcinoid tumor 因為pathology 是small blue cell, 所以只剩下small cell lung cancer跟bronchial carcinoid tumor 因為題幹沒有提到 carcinoid syndrome的症狀, 所以要把bronchial carcinoid tumor 刪掉 elimination (step 1 的題目就是考典型, 所以如果題幹沒有提到, 但是某個選項一定有的症狀, 那就不是那個選項) 所以答案就是small cell lung cancer, 然後會有ADH過多的症狀→SIADH, hyponatremia 參考圖片: https://www.facebook.com/615598082416899/photos/p.728651974444842/728651974444842/?type=3&av=615598082416899&eav=AfYvF5lp_O0TZCPrs0luC2WvS8AgjwB2_tVnmOfUpA8qm2w8tfMgrwCvJDyKlnP2Lr4
submitted by ∗cassdawg(1780)
The description points toward small cell carcinoma of the lung (a small blue cell tumor, FA2020 p684, 228)
Small cell lung cancer has a very high association with ectopic ADH secretion as a paraneoplastic syndrome. Ectopic secretion of ADH (SIADH, p338) leads to hyponatremia primarily by increased volume and subsequent inhibition of the RAAS (renin-angiotensin-aldosterone system) which causes loss of sodium.