Bronchopulmonary foregut malformations (BPFMs) are a wide-encompassing term referring to several types of anomalies of pulmonary development resulting from abnormal budding of the embryonic foregut and tracheobronchial tree. BPFMs include foregut duplication cysts, pulmonary sequestrations, and congenital pulmonary airway malformations (CPAMs) .
Foregut duplication cysts arise from abnormal budding of the embryonic foregut and tracheobronchial tree and can be classified into three groups: bronchogenic, neuroenteric, and enteric cysts. Bronchogenic cysts arise from abnormal budding of the bronchial tree around 4–6 weeks gestation and are lined by secretory respiratory epithelium . Esophageal duplication cysts, a type of enteric cyst, arise from the posterior division of the embryonic foregut at 3–4 weeks gestation and are lined by gastric epithelium .
Pulmonary sequestration is defined as the aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries . It receives systemic arterial blood supply, usually from the thoracic or abdominal aorta. Venous return can either be pulmonic or systemic. There are two types of sequestration: extralobar pulmonary sequestration which has its own distinct pleural covering and complete separation from adjacent lung tissue, and intralobar pulmonary sequestration which is embedded in the normal lung [4, 5]. There is a predilection for the posterior inferior chest, with 90% of extralobar sequestration occurring on the left side. This contrasts with our patient who was found to have extralobar sequestration in the right superior chest.
Embryology could help to explain the occurrence of some of these congenital anomalies simultaneously. Between 3 and 5 weeks of gestation, the tracheobronchial tree is formed by a median bud that forms on the ventral wall of the pharynx and grows caudally to form the right and left lung buds [4, 5]. As these lung buds elongate, lateral ridges form between the lung buds and dorsal foregut to create the tracheoesophageal septum which separates the esophagus from the trachea. The presence of supernumerary lung buds that arise from the primitive foregut caudal to the normal lung buds is considered the most common factor in the development of all forms of BPFMs . Which type of BPFM develops depends on (1) the stage of embryological development when the accessory tissue arises, (2) the direction in which the aberrant pulmonary tissue grows, and (3) the retention or involution of the communication between the accessory lung tissue and the parent viscus .
Foregut duplication cysts arise during the same period of embryogenesis as that of the development of the lung buds. While pulmonary sequestrations are already a very rare malformation with an estimated incidence of 0.15–6.4% , extralobar sequestration is less common than intralobar sequestration comprising about 25% of all sequestrations. They have a greater prevalence to be associated with other congenital malformations (65%) than the intralobar type, with the most common being diaphragmatic hernia (16%). Other associations include congenital cystic adenomatoid malformation (CCAM), bronchogenic cysts, pectus excavatum, pericardial defects, and enteric duplication cysts . Very few case studies have cited the rare association between extralobar pulmonary sequestration and bronchogenic cyst  or complex bronchopulmonary foregut malformations of the mixed bronchogenic and esophageal type [2, 8]. Most of these lesions occurred in the left hemithorax [2, 7].
Surgical resection is the treatment of choice where extralobar sequestrations can usually be removed without harm to normal lung tissue because it is invested in its own pleura. Surgical excision was also considered the treatment of choice for bronchogenic cysts, especially symptomatic lesions, although more recently, less invasive methods are advocated including videothoracoscopy, mediastinoscopy and the percutaneous approach .