Extralobar pulmonary sequestration.

Tissues of bronchopulmonary origin, which have no communication with the bronchial tree and are supplied by anomalous vessels, are relatively rare and have been referred to by a variety of terms. These include accessory lung, sequestrated lobe of lung, ectopic lobe of lung, dissociated or dislocated lobe, aberrant lobe, or supernumerary lobe. The term 'sequestrated lobe' may not be entirely appropriate but it is consecrated by use. Such a lobe may be classified as intralobar, extralobar, or complete sequestration, depending on its anatomical relationship to the main lung masses. The earlier examples of the abnormality were described by Rokitansky (1861) and Rektorzik (1861), and since then the entity has been recognized more frequently (Harris and Lewis, 1940; Gruenfeld and Gray, 1941; Arce, 1943; Davies and Gunz, 1944; Pryce, Sellors, and Blair, 1947; Lemmon, Kirklin, and Dockerty, 1954), In fact, this condition is not peculiar to man; at least 21 cases have been reported in cattle and one case in a horse (Davidson, 1956). The intralobar variety appears to be the commonest and more than 250 cases have been reported in the literature (Ranniger and Valvassori, 1964). There are, however, fewer reports of the extralobar and complete varieties. The disparity in occurrence between the intralobar variety and the extralobar and complete varieties may be due to the fact that the latter two are not as susceptible to infective complications as the intralobar variety and therefore are less frequently detected. Furthermore, the intralobar variety from its anatomical location is often detected in the course of investigations for other pulmonary lesions which it may simulate on clinical or radiological grounds. The case presented here is an incidental necropsy finding in a Nigerian child who died from bacterial enterocolitis but had a right-sided extralobar sequestrated lobe attached anteriorly to the right pulmonary artery by a fibrovascular pedicle.