A case of ACTH producing oat cell carcinoma cause of ectopic Cushing's syndrome and life threatening hypokalaemia

Abstract

Introduction: Ectopic Cushing’s syndrome caused by ectopic ACTH secretion are under-diagnosed.Case report: A 50 years old male patient is hospitalized for severe hypokalaemia and diabetes.Last 6 months he had a history of chest pain, prolonged cough, general weakness, difficultiesclimbing stairs, confusion, loss of consciousness. Previously, he was hospitalized in psychiatrichospital for psychotic alterations, in cardiology for high blood pressure and cardiomyopathy (Ef40%). Type 2 diabetes is diagnosed before 3 months; treated with basal insulin. Initialinvestigations revealed Na 144 mmol/l (135–145), K+ 1.9 mmol/l (3.5–5.2), Urea 9 mmol/l, Cr(s)47 mmol/l, Glu(s) 9 mmol/l. DXA confirmed osteoporosis (T-score >−2.5). Basal cortisol 1300nmol/l, Daily rhythm of cortisol during 24 h was >1750 nmol/l. ACTH 641.2 pg/ml (7.2–63.6).On chest x ray it was suspicious tumoral mass, confirmed with chest CT. Tumor mass waspresent on upper mediastinum to the left until hilus, enlarged mediastinal lymph nodes,infiltration on the left lobe and pleural effusion in the same part. Gas analysis: partialymanifested respiratory insufficiency. Endoscopic bronchoscopy with ultrasound (EBUS) wasperformed for cyto/immunocytochemical analysis for ACTH. Citologycaly confirmed IVclassification group of malignancy – oat cell carcinoma and immunocytochemy for ACTH waspositive in 5–10% of neoplastic cells and positive for chromogranin in 30–40% and NSE in 50–60% of tumoral population. Patient was referred to Clinic of Pulmology and Institute ofOncology.Conclusion: Diagnosis of ectopic Cushing’s syndrome explain other co-morbidities such ashypokalaemia, diabetes, osteoporosis, psychosis. Appropriate diagnostic procedures withoutadditional tests (dexamethasone suppression test, MRI), accelerates the diagnosis of this life-threatening patient

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