Carcinoid Tumours of the Lung
Neuroendocrine tumours of the airway — from typical carcinoid to adenoid cystic carcinoma.
Overview
Bronchial carcinoids are part of the neuroendocrine tumour (NET) spectrum. They arise from Kulchitsky cells — neuroendocrine cells that secrete amines and peptides. Only typical and atypical carcinoids are classified as bronchial adenomas; large cell neuroendocrine carcinoma and small cell carcinoma represent high-grade NETs.
| Typical carcinoid | Atypical carcinoid | LCNEC | SCLC | |
|---|---|---|---|---|
| Grade | Low | Intermediate | High | High |
| Mitoses/HPF | <2 | 2–10 | >10 | >10 |
| Ki67 | <3% | Up to 20% | High | High |
Typical vs. atypical carcinoid
| Feature | Typical carcinoid | Atypical carcinoid |
|---|---|---|
| Proportion | 75% | 25% |
| Kulchitsky type | Type 1 | Type 2 |
| Sex predominance | M = F | M > F |
| Location | Central (endobronchial) | Peripheral |
| Mitoses/HPF | <2 | 2–10 |
| Ki67 | <3% | >20% |
| Prognosis | Excellent — 10-yr DFS ~85–90% | Poor — 10-yr DFS ~50% |
Clinical features
Primary tumour symptoms
Central carcinoids present with obstructive symptoms — cough, dyspnoea, wheeze, haemoptysis, recurrent pneumonia, atelectasis, and bronchiectasis. Classic triad: endobronchial obstruction causing stridor, unilateral wheeze, and haemoptysis. About one-quarter of all carcinoids are asymptomatic.
Carcinoid syndrome
Seen in <2% of bronchial carcinoids — associated with large or metastatic lesions. Features: episodic flushing, diarrhoea, tachycardia, bronchoconstriction, and haemodynamic instability (due to serotonin, histamine, and 5-HIAA secretion).
Paraneoplastic syndromes
Seen in <1% — ectopic ACTH secretion (Cushing's syndrome), acromegaly, SIADH, and hypoglycaemia have all been described.
Investigations
- CT: characterises the lesion, identifies hilar and mediastinal nodes
- PET/CT: useful for identifying malignant carcinoid lesions
- Gallium-68 dotatate PET/CT: increasingly used for localising somatostatin receptor-positive NETs — particularly useful for staging
- Octreoscan (SRS): detects lymph nodes and distant metastases; inflammatory areas may give false positives
- Bronchoscopy and biopsy: ~80% of carcinoids are visible bronchoscopically; deeper biopsies required as tumours lie beneath the epithelium; caution — these are highly vascular tumours and bronchoscopic biopsy may cause severe haemorrhage
Treatment
Carcinoids are chemo- and radioresistant — surgery is the only curative modality. ALL carcinoid tumours, irrespective of histological grade, should be treated by complete excision with appropriate lymph node dissection due to the propensity for recurrence.
Bronchoplastic sleeve resection where feasible — excellent long-term results. Preferred to preserve lung function, especially in young patients.
Segmentectomy or lobectomy with mediastinal node dissection — standard for most cases.
Reserved for patients with poor cardiopulmonary reserve only — high local recurrence risk.
Bronchoscopic resection should NOT be used as definitive treatment. These tumours typically penetrate beyond the bronchial wall into local parenchyma by the time they are discovered, and lymph node staging cannot be performed. Bronchoscopic debulking is acceptable only for pre-operative palliation of obstruction before formal surgical resection, or as palliation in patients unfit for surgery.
Somatostatin analogues (octreotide) control carcinoid syndrome. Systemic chemotherapy and peptide receptor radionuclide therapy (PRRT) for progressive metastatic disease. Refer to ENETS guidelines for current protocols.
Bronchial gland tumours
Adenoid cystic carcinoma (cylindroma)
Most commonly occurs in the trachea. Characterised by submucosal and perineural lymphatic spread — associated with high local recurrence despite wide excision. About one-third have lymph node metastasis at presentation. Treatment: wide surgical excision with nodal dissection; palliative radiotherapy for unresectable or metastatic disease. 50% long-term survival with complete resection.
Mucoepidermoid carcinoma
Arises from accessory salivary glands in the trachea and proximal bronchi. Has the same microscopic appearance as mucoepidermoid carcinoma of the salivary glands. Treatment: complete resection. Prognosis depends on tumour grade.
All clinical content should be verified against current guidelines before clinical application. This resource is intended for revision and educational purposes only.
Standard textbooks
- Shields TW, LoCicero J, Reed CE, Feins RH. General Thoracic Surgery. 7th ed. Lippincott Williams & Wilkins.
- Sellke FW, del Nido PJ, Swanson SJ. Sabiston & Spencer Surgery of the Chest. 9th ed. Elsevier.
- Pearson FG, et al. Thoracic Surgery. 3rd ed. Churchill Livingstone.