Ectopic adrenocorticotropic hormone-secreting carcinoid with solitary cryptococcosis in the lungs

Background Carcinoid tumors can on rare occasions ectopically produce adrenocorticotropic hormone (ACTH), causing Cushing's syndrome, and patients could become immunocompromised. Care must therefore be taken regarding infectious complications. In particular, ACTH-producing pulmonary carcinoid is not easy to diagnose by itself, and when combined with pulmonary nodules as infectious foci, each is very difficult to diagnose. Case The patient was a 71-year-old woman with refractory diabetes. She showed clinical symptoms of Cushing's syndrome during treatment for diabetes and ectopic ACTH production was suspected based on biochemical and imaging tests. Nodules were identified in the left lung apex and lingual segment. Examination of resected nodules revealed that the nodule in the apex was pulmonary cryptococcosis, while the nodule in the lingual segment represented typical carcinoid. After surgery, clinical symptoms, laboratory findings, and diabetes all improved. Conclusion We present this very instructive case in terms of the difficulty of diagnosing ACTH-producing tumors, the possibility of infection complicating the immunodeficiency caused by ACTH-producing tumors, and the surgical strategy.