title: Syndrome of inappropriate antidiuretic hormone secretion in a patient with cryptococcal meningoencephalitis: a hidden mediastinal small cell carcinoma.
abstract: We report a 59-year-old man with cryptococcal meningoencephalitis who presented with typical features of syndrome of inappropriate antidiuretic hormone secretion (SIADH). There was no evidence of lung disease or drugs causing SIADH. Studies for endocrine functions and tumor markers were normal. The patient's hyponatremia was refractory to treatment (Na 120-125 mmol/L) after resolution of the cryptococcal infection. Three months after completion of antifungal treatment, a radiograph of the chest disclosed widening of the mediastinum. Computed tomography revealed a mediastinal mass. A tentative diagnosis of extrapulmonary cryptococcoma or a tumor was made. Positron emission tomography using F-fluorodeoxy glucose demonstrated an intense uptake mass in the mediastinum without lesions elsewhere in the body. A biopsy of the mass clearly showed small cell carcinoma (SCC) with positive immunoreactivity for arginine vasopressin and atrial natriuretic peptide. The hyponatremia completely resolved and tumor size dramatically decreased after chemotherapy. To the best of our knowledge, this is the first case of mediastinal SCC associated with SIADH. Patients with otherwise unexplained SIADH should be meticulously scrutinized for a possible malignancy.
authors.affiliation: Division of Nephrology, Department of Medicine, Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: Chan-Chih
authors.initials: CC
authors.lastname: Yang
authors.forename: Herng-Sheng
authors.initials: HS
authors.lastname: Lee
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Chen
authors.forename: Chih-Jen
authors.initials: CJ
authors.lastname: Cheng
authors.forename: Shih-Hua
authors.initials: SH
authors.lastname: Lin
mesh_terms: D018288:Carcinoma, Small Cell / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy; D002945:Cisplatin / Q000627:therapeutic use; D005047:Etoposide / Q000627:therapeutic use; D015725:Fluconazole / Q000627:therapeutic use; D006801:Humans; D007010:Hyponatremia / Q000150:complications / Q000175:diagnosis; D007177:Inappropriate ADH Syndrome / Q000175:diagnosis / Q000209:etiology*; D008297:Male; D008479:Mediastinal Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000188:drug therapy; D016919:Meningitis, Cryptococcal / Q000150:complications* / Q000188:drug therapy; D008590:Meningoencephalitis / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy; D008875:Middle Aged; D049268:Positron-Emission Tomography
chemical_list: D005047:Etoposide; D015725:Fluconazole; D002945:Cisplatin