Acromegaly in association with a bronchial carcinoid tumour

Abstract

Bronchial carcinoid tumours are uncommon pulmonary neoplasms. Manifestation of a bronchial carcinoid with acromegaly secondary to extra-pituitary growth hormone releasing hormone (GHRH) productionis rare, but bronchial carcinoid tumours are the most common cause of ectopic GHRH secretion. We report the case of 60 year old female, ex-smoker with hypertension presenting with cough,dyspnoea and right lower lobe opacity on the chest X-ray. Patient was noted to have features of acromegaly and IGF-1 was requested. Subsequent CT TAP showed a right lower lobe collapse, 4.5 cm mass obstructing the lower lobe bronchus which was visualised but could not be biopsied during bronchoscopy. 18-FDG PETCTscan showed only mildly avid right lower lobe mass, likely to be a slow growing carcinoid tumour, with chronic collapse of the right lower lobe. Pre-operative IGF-1 level came back elevated at 67 nmol/l. Patient underwent right mid and lower lobectomies and the histology showed morphological appearance of grade 1 neuroendocrine carcinoma (classic carcinoid tumour) with no lymph node involvement. Patient underwent the oral glucose tolerance test (OGTT) with growth hormone (GH) levels reaching a nadir value of 0.82 µ/L. Patient's pituitary hormone profile and the MRI of the pituitary gland were both normal. The GHRH assay was not available.The most recent postoperative random GH level was 0.6 µ/L and IGF-1 was 20 nmol/L. Bronchial carcinoid tumours are one of the commonest causes of ectopic GHRH production, with similar cases reported in the literature. In the view of possible insufficient normalisation of the GH levels post OGTT our patient will require further close follow up. Our case represents the classic carcinoid tumour which is reported to have very good prognosis following surgical resection. The results of staining for GHRH on tissue samples are still awaited as the samples are being processed abroad.