Abstract
Innumerable carcinoid tumourlets may develop within pulmonary lobes should there be scarring from intralo bar sequestration; these tumourlets may, in turn, be the cause of chronic lung disease. This report documents the incidental detection of multifocal carcinoid tumourlets in the lung of a 65-year-old man who had repeated episodes of lung infection, progressive dysp nea and haemoptysis; he lived at high altitude. The left lower lobe of the lung was resected surgically, during which procedure an aberrant systemic arterial supply was noticed. The patient had diffuse bronchiectasis and intralobar sequestration. The latter implies the development of abnormal lung tissue located within lobar tissue - but which does not communicate with the bronchial tree; it is supplied with arterial blood from a branch of the aorta - arising either above or below the diaphragm. There was loss of demarcation between the sequestered lung and the surrounding lower lobe lung parenchyma. The proliferation of pul monary neuroendocrine cells in the form of tumourlets, had probably occurred as an adaptive response to the chronic hypoxia experienced. The combination of intralobar sequestration, bronchiecta sis and carcinoid tumourlets, although uncommon, may arise when intralobar sequestration of the lung has not been resected at an incipient stage.