Ectopic tumors account for about 20 percent of all cases of ACTH-dependent Cushing syndrome. The vast majority of these are located in the thorax, with bronchial neuroendocrine tumors being the leading cause (up to 54 percent), as noted by Maria Vittoria Davi, M.D., and colleagues in the European Journal of Endocrinology in 2017 and Jaroslaw Aniszewski, M.D., and others in the World Journal of Surgery in 2001.

Due to their small size, effective preoperative localization can be problematic. The patient reported here was evaluated before the Food and Drug Administration approval of gallium 68 (68-Ga) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE) for PET-CT. Andrea M. Isidori, M.D., Ph.D., and others reviewed conventional and nuclear medicine imaging in ectopic Cushing syndrome in The Journal of Clinical Endocrinology & Metabolism in 2015. A 68-Ga DOTATATE-PET-CT scan may or may not have localized the ACTH-secreting bronchial neuroendocrine tumor in our patient.

In concert with advances in targeted imaging for neuroendocrine tumors, there have been advances in minimally invasive therapy allowing delivery of cryoablation probes to small tumors. Cryoablation induces cancer cell death by activating a number of molecular and cellular processes during the freeze-thaw cycles leading to cancer cell destruction and tissue necrosis, with protection of surrounding normal lung tissue.

Subsequent inflammatory and immune reactions continue for hours to days following the procedure to achieve local tumor control — as reported by Thierry de Baere, M.D., and colleagues in the Journal of Thoracic Oncology in 2015 and Masanori Inoue and others in BioMed Research International in 2014.