Cushing's syndrome caused by ectopic corticotropin secretion by multiple peripheral pulmonary carcinoids and tumorlets of carcinoid type

Multiple peripheral pulmonary carcinoid tumors or their smaller counterpart s (tumorlets of carcinoid type) are the most unusual form of carcinoids as a cause of ectopic corticotropin syndrome. Only three case reports were fou nd in the literature. We describe a 35 year-old female patient with ectopic corticotropin secretion due to multiple peripheral pulmonary carcinoid tum ors and tumorlets. A high-dose dexamethasone suppression test result led to the diagnosis of Cushing's disease in our case. But no tumor was identifie d on sella imaging and bilateral inferior petrosal sinus sampling was non-d iagnostic. Computed tomography of the lungs revealed multiple acinar-nodula r parenchymal infiltrations confined to the left lung. Corticotropin-depend ent hypercortisolism persisted after bilateral adrenalectomy. A second oper ation was necessary to remove the hyperplastic adrenal remnants. Meanwhile, computed tomography findings of the thorax were unchanged. We decided to e xplore these nodules by open lung biopsy. During the procedure multiple nod ules ranging 12 to 3 mm in diameter scattered throughout the left lung were observed and left pneumonectomy was performed. Histopathological diagnosis was multiple peripheral carcinoid tumors and tumorlets of carcinoid type s howing positive immunostaining with corticotropin. This observation emphasi zes a rare form of carcinoids as a cause of ectopic corticotropin secretion and its unusual response to high dose dexamethasone suppression test. (J. Endocrinol. Invest. 23: 536-541, 2000) (C) 2000, Editrice Kurtis.