Intralobar Pulmonary Sequestration

I read with interest the case of intralobar pulmonarysequestration (ILS) that appeared in the June 2000 issue ofCHEST as a Roentgenogram of the Month.1Lewis MM Tsou E A 66-year-old man with dyspnea, left lower lobe infiltrate, and abnormal imaging.Chest. 2000; : 1782-1786Abstract Full Text Full Text PDF Scopus (11) Google Scholar The development of ILS, one of the most interesting developmentalpulmonary abnormalities, has not been elucidated yet. I do not agreewith the comments of the authors on this case regarding the etiology asbeing both acquired and congenital in the same patient. The quite rareand large aberrant systemic artery originating from the leftcircumflex coronary artery and reaching the left lower lobe is proofenough that this case is congenital in origin. In the study of Stockerand Makzak,2Stocker JT Makzak HT A study of pulmonary ligament arteries: relation to intralobar pulmonary sequestration.Chest. 1984; 86: 611-615Crossref PubMed Scopus (95) Google Scholar arteries from the thoracic aorta branchinginto the visceral pleura traversing the ligamentum pulmonale have beenfound to be anatomically present, and, depending only on thatcriterion, it was claimed that a chronically infected lesionobstructing a bronchus and occluding the pulmonary artery could causeacquired ILS by means of systemic arterial parasitization from aorticarteries traversing the ligamentum pulmonale. The following factors are in favor of this hypothesis: no ILS caseamong 42,000 infants < 2 months of age3Stocker JT Kagan-Hallet K Extralobar pulmonary sequestration: analysis of 15 cases.Am J Clin Pathol. 1979; 72: 917-925Crossref PubMed Scopus (88) Google Scholar; normalpulmonary venous drainage; the rarity of ILS in lobes other than thelower lobes (pulmonary ligament arteries do not exist in the upperlobes); and fewer ILS cases with other abnormalities when compared toextralobar sequestration (ELS) cases.2Stocker JT Makzak HT A study of pulmonary ligament arteries: relation to intralobar pulmonary sequestration.Chest. 1984; 86: 611-615Crossref PubMed Scopus (95) Google Scholar3Stocker JT Kagan-Hallet K Extralobar pulmonary sequestration: analysis of 15 cases.Am J Clin Pathol. 1979; 72: 917-925Crossref PubMed Scopus (88) Google Scholar But thishypothesis cannot explain patients with both ILS and ELS, patients with ILS who have gut fistulas, accompanying congenital malformations with an incidence of 14%, bilateral sequestrations of the same or differenttypes, ILS patients with upper lobe localization, or cases of ILS inneonates.4Kaemmerlen JT Sequestrated information.Chest. 1984; 86: 510-511Crossref Scopus (1) Google Scholar5Savic B Birtel FJ Tholen W et al.Lung sequestration: report of seven cases and review of 540 published cases.Thorax. 1979; 34: 96-101Crossref PubMed Scopus (514) Google Scholar6Karp N Bilateral sequestration of the lung.AJR Am J Roentgenol. 1977; 128: 513-515Crossref PubMed Scopus (7) Google Scholar7Trudel JA Lemire G Rabbat A Bilateral sequestrations of different type with mirror-image vascularization.Chest. 1977; 72: 256-257Crossref PubMed Scopus (6) Google Scholar8Sege D Simultaneous intra- and extralobar lung sequestration and its intermediate stages.Helv Chir Acta. 1990; 57: 261-268Google Scholar9Hoeffel JC Bernard C Pulmonary sequestration of the upper lobe in children.Radiology. 1986; 160: 513-514Crossref PubMed Scopus (15) Google Scholar10Niggemann B Magdorf K Waldschmidt J et al.Cystic pulmonary lesion in a 6 year old girl.Eur Respir J. 1994; 7: 211-212Crossref Scopus (2) Google Scholar11Mohan K Kramer N Margolis ML et al.ILS in conjunction with bronchial isomerism.Thorax. 1983; 38: 77-79Crossref PubMed Scopus (3) Google Scholar12Corrin B Danel C Allaway A et al.ILPS of ectopic pancreatic tissue with gastropancreatic duplication.Thorax. 1985; 40: 637-638Crossref PubMed Scopus (10) Google Scholar13Sauvanet A Regnard JF Calanducci F et al.Pulmonary sequestration: surgical aspects based on 61 cases.Rev Pneumol Clin. 1991; 47: 126-132PubMed Google Scholar14Dieltjens A Naulaers G Vandeven K et al.Right diphragmatic eventration associated with intralobar pulmonary sequestration: a case report.Eur J Pediatr Surg. 2000; 10: 140-141Crossref PubMed Scopus (7) Google Scholar15Hattari Y Negi K Takeda I et al.ILPS with arterial supply from the left internal thoracic artery: a case report.Ann Thorac Cardiovasc Surg. 2000; 6: 119-121Google Scholar16Lane SD Burkott H Scott HW Congenital BPFM.Radiology. 1971; 101: 291-292Crossref PubMed Scopus (6) Google Scholar17Durnin RE Lababidi Z Butler C et al.Bronchopulmonary sequestration.Chest. 1970; 57: 454-459Crossref PubMed Scopus (17) Google Scholar Besides this, it is clear in this case thatthere is no need for the acquired neovascularization (parasitizationfrom aortic arteries) of sequestrated lung tissue that has already beensupplied by an artery large enough and is unquestionably congenital inorigin. The wheel theory of Clements et al18Clements BS Warner J Shinebourne EA Congenital bronchopulmonary vascular malformations: clinical application of a simple anatomical approach in 25 cases.Thorax. 1987; 42: 409-416Crossref PubMed Scopus (32) Google Scholar seems tobe more acceptable in explaining the development of congenitalbronchopulmonary malformations. According to Clements etal,18Clements BS Warner J Shinebourne EA Congenital bronchopulmonary vascular malformations: clinical application of a simple anatomical approach in 25 cases.Thorax. 1987; 42: 409-416Crossref PubMed Scopus (32) Google Scholar ILS and ELS have similar origins. If the patient with ILS whose case was presented by Lewis and Tsou1Lewis MM Tsou E A 66-year-old man with dyspnea, left lower lobe infiltrate, and abnormal imaging.Chest. 2000; : 1782-1786Abstract Full Text Full Text PDF Scopus (11) Google Scholar had been operated on and, thus, had had ILShistopathologically confirmed (eg, bronchial obstruction, occlusion of the pulmonary artery, or a type of pleural envelopelesion), collateral vessels originating from the aortic arch and reaching the lesion could have been claimed to be acquired originallybecause of neovascularization secondary to chronic infection. This caseis congenital in origin because of the abnormal arteryoriginating from the circumflex artery. In addition, ELS is frequently localized in the left lower lobe, justbetween the lobe and the diaphragm in its own pleural envelope. Thetype of pleural envelope in the lesion (IL-EL) cannot be detected by CTscanning alone but requires histopathologic verification. The venousdrainage in this case also has not been clearly identified. Pulmonaryvenous drainage is characteristic in patients with ILS. When thediagnosis is uncertain, surgery is the rule insequestrations.13Sauvanet A Regnard JF Calanducci F et al.Pulmonary sequestration: surgical aspects based on 61 cases.Rev Pneumol Clin. 1991; 47: 126-132PubMed Google Scholar Two other limitations of this case are the discordance with theacquired ILS hypothesis of Stocker and Makzak,2Stocker JT Makzak HT A study of pulmonary ligament arteries: relation to intralobar pulmonary sequestration.Chest. 1984; 86: 611-615Crossref PubMed Scopus (95) Google Scholar in thatarteries do not reach the lesion via the ligamentum pulmonale, and thelack of a bronchologic study. There are ILS cases with communication tothe tracheobronchial tree or cases in which inflammatory changes occurin adjacent bronchi.19Iwai K Shindo G Hajikano H et al.ILPS with special reference to developmental pathology.Am Rev Respir Dis. 1973; 107: 911-920PubMed Google Scholar In this case, the patient has ahistory of bronchitis of quite a long duration. Collateral arteriesfrom the aortic arch to the lesion are not proof enough that the lesionwas acquired. Besides, by means of collateral ventilation, thesequestrated portion of the lung in patients with ILS can be ventilatedand infected.20Hopkins RL Levine SD Waring WW ILS: demonstration of collateral ventilation by nuclear lung scan.Chest. 1982; 82: 192-193Crossref Scopus (5) Google Scholar The above-mentioned sequential events donot necessarily mean that ILS is acquired as a result of infection. I believe that this case of sequestration is congenital in origin, and, with respect to the above-mentioned reasons, it will not be objectiveto define the etiology of this case as both congenital and acquiredunless further investigations concerning venous drainage, type of pleural envelope of the lesion, and aortic vessels to the lesion, aswell as bronchologic studies, are performed.