Mandaliya Rohan, Hughes Lesley, Auerbach Herbert, LePar Felice
Department of Internal Medicine, Abington Memorial Hospital, Abington, PA 19001, USA.
Temple University School of Medicine, Philadelphia, PA 19140, USA.
Case Rep Oncol Med. 2014;2014:874831. doi: 10.1155/2014/874831. Epub 2014 May 15.
A 70-year-old female with a history of mild cirrhosis was referred by her primary care provider for a platelet count of 36,000/ μ L which had dropped from 47,000/ μ L in a week along with mild pain in extremities. Serum potassium was low (2.9 mEq/L) in spite of the patient being recently started on potassium supplement on outpatient for hypokalemia. Initially thrombocytopenia was attributed to cirrhosis. However, platelet counts continued to drop to a nadir of 9000/ μ L in spite of several platelet transfusions. Hypokalemia was refractory to potassium supplements. Subsequent bone marrow biopsy revealed extensive marrow necrosis with a focus of small cell tumor cells of pulmonary origin. CT scan of the chest showed a spiculated left lung mass. The ACTH level was high, with normal rennin and aldosterone levels. The patient likely had ectopic ACTH syndrome from small cell lung cancer. She died within few days of diagnosis. Severe thrombocytopenia and refractory hypokalemia can rarely be initial presentations of small cell lung cancer. Thrombocytopenia should prompt an evaluation for bone marrow metastases and a search for undiagnosed systemic malignancy. In severe cases of metastases, bone marrow necrosis can be present. Refractory hypokalemia can be the sole presentation of ectopic ACTH production.
一名70岁女性，有轻度肝硬化病史，其初级保健医生因其血小板计数从一周前的47,000/μL降至36,000/μL并伴有轻度肢体疼痛而将其转诊。尽管患者最近因低钾血症在门诊开始补钾，但血清钾仍低（2.9 mEq/L）。最初，血小板减少归因于肝硬化。然而，尽管多次输注血小板，血小板计数仍继续降至最低点9000/μL。低钾血症对补钾治疗无效。随后的骨髓活检显示广泛的骨髓坏死，并伴有起源于肺部的小细胞肿瘤细胞灶。胸部CT扫描显示左肺有一个毛刺状肿块。促肾上腺皮质激素（ACTH）水平升高，肾素和醛固酮水平正常。该患者可能患有小细胞肺癌引起的异位ACTH综合征。她在诊断后几天内死亡。严重血小板减少和难治性低钾血症很少是小细胞肺癌的初始表现。血小板减少应促使对骨髓转移进行评估，并寻找未诊断的全身性恶性肿瘤。在严重转移病例中，可能会出现骨髓坏死。难治性低钾血症可能是异位ACTH分泌的唯一表现。
