Endocrine Abstracts

Introduction: DIPNECH is a preinvasive condition in which there is an idiopathic generalised proliferation of pulmonary neuroendocrine cells that can form tumourlets. There are very few cases described of ACTH secretion by these cells causing Cushing’s syndrome, some of them cyclic.

Case report: A 41 year-old woman was sent to our Endocrinology outpatient clinic for menstrual disturbance, acne and excessive sweating. She had a recent diagnosis of DIPNECH after extensive investigation for long standing dry cough and dyspnea and was already on prednisone 35 mg/day and inhaled corticosteroids for a few months. Physical examination: moon face, slightly pletoric; excessive weight, prominent abdomen with purple striae; mild facial and dorsal acne; buffalo hump and cervical acanthosis nigricans. No other relevant findings. Blood tests revealed slightly elevated IGF-1 (242 ng/mL [58–219]) and hyperprolactinemia (85 pg/mL [4.8–23]). Cortisol metabolism was not tested at the time because of corticosteroid treatment. OGTT was performed, with no clear evidence of acromegaly. Immunohistochemistry of the tumourlet neuroendocrine cells was negative for GH, but strongly positive for ACTH. No lesions were present in the sellar MRI. The patient was then started on octreotide to optimize DIPNECH treatment because she still complained of dyspnea, with some improvement. Steroids were tapered down progressively with good tolerance but not much improvement of Cushingoid features. After full withdrawal for a few days, we tried to evaluate the patient for ectopic Cushing’s syndrome. Cortisol rhythm was normal, CRH test had a raise in ACTH of 120% and 40% of cortisol. Overnight dexamethasone suppression test (2 mg) was negative (cortisol 0.2 mcg/dL [<1.8 mcg/dL]). Urinary free cortisol level is still pending. There is no evidence of hypersecretion so far, but the patient is going to be followed and repeat these tests after a longer period with full steroid withdrawal and just before the next octreotide administration, since it can also influence results.

Conclusion: This case represents a true diagnostic challenge, since we can be in the presence of inactive ACTH, real ectopic Cushing’s syndrome that is biochemically responding to octreotide or cyclic ectopic Cushing’s syndrome. Follow-up will be essential do unravel the true meaning of the immunohistochemistry findings.