Bronchial carcinoid tumours - Respiratory oncology

Bronchial carcinoid tumours

Definition

A rare neuroendocrine tumour of the lung.

Pathophysiology

These are highly vascular, low-grade malignant tumours which are locally invasive and can metastasise. They arise from bronchial enterochromaffin (Kulchitsky) cells, and can secrete various amines and peptides, including serotonin (5-hydroxytryptamine (5HT)), histamine and bradykinin. These rarely cause the carcinoid syndrome, as to do so they have to metastasise to the liver first (the peptides are metabolised in the liver).

Clinical features

The tumour can present with obstruction, recurrent haemoptysis or with metastatic disease. There may be weight loss.

Macroscopy/microscopy

They arise from lobar or segmental bronchi into which they protrude as a rounded mass usually covered by intact epithelium. Cells are cuboidal, arranged in a mosaic or trabecular pattern and have a dense core and neurose-cretory granules.

Complications

1.     Lung collapse and consolidation distal to the obstruction.

2.     Local invasion, spread to lymph nodes and distant metastasis.

3.     Rarely, the carcinoid syndrome – recurrent episodes of a combination of

·        flushing of the face and neck sometimes leading to telangectasia (due to kinins).

·        abdominal pain, nausea, vomiting and watery diarrhoea (5HT).

·        tricuspid regurgitation or pulmonary stenosis.

Investigations

Chest X-ray may show a rounded lesion.

Bronchoscopy usually shows a pedunculated vascular tumour protruding into the lumen.

24-hour urinary excretion of the metabolite of 5HT. (5-hydroxyindoleacetic acid (5-HIAA)) on a low serotonin diet (excluding bananas, tomatoes, walnuts, etc.)

Management

Local resection is indicated in all cases.

Prognosis

80% 10-year survival.