Ann Thorac Surg 2003;76:2077-2078
© 2003 The Society of Thoracic Surgeons
Case report
Complex extralobar sequestration in a 24-year-old woman
Anna Arslanian, MDa,
Nicole Leflour, MDb,
Anne Hernigou, MDc,
Claire Danel, MDd,
Marc Riquet, MDa*
a Service de Chirurgie Thoracique, Villeneuve Saint Georges, France
b Service de Medecine Interne, Centre Hospitalier Intercommunal, Villeneuve Saint Georges,, France
c Service de Radiologie, Paris, France
d Service d'Anatomie Pathologique, Hôpital Européen Georges Pompidou, Paris, France
Accepted for publication April 1, 2003.
* Address reprint requests to Dr Riquet, Service de Chirurgie Thoracique, Hôpital Européen Georges Pompidou, 20-40 rue Le Blanc, 75015 Paris, France
e-mail: marc.riquet{at}hop.egp.ap-hop-paris.fr
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Abstract
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Extralobar sequestration is a congenital acquired disease more frequently observed after birth or during infancy. In half of the cases, it is associated with another malformation. In the following case we report the observation of a 24-year-old female with right extralobar sequestration associated with a diaphragmatic hernia and containing gastric mucosa and a congenital cystic adenomatoid lung malformation. Such malformative lung tissue is known to potentially degenerate and justifies surgery even when patients are asymptomatic.
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Introduction
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The term pulmonary "sequestration" is applied to a pulmonary lobe or portion of a lobe which is supplied separately by a large anomalous artery arising from the aorta or one of its branches [1]. In extralobar sequestration (ELS), the so-called accessory lung is separated from the normal lung and contained within its own pleura with its venous drainage, usually to the systemic venous system [2]. Among 540 cases of pulmonary sequestration published between 1962 and 1975, ELS was found in 133 cases (24.6%). In the majority of cases, ELS was close to the diaphragm (77%), in the left suprarenal area (90%), and associated with other congenital malformations in approximately 50% of cases (56 out of 133 [2]). A diaphragmatic hernia was observed to be associated in 30% of the cases. The coexistence of a congenital cystic adenomatoid malformation (CCAM) has been underdiagnosed until Conran and Stocker [3] recently demonstrated its possible occurrence in up to 50% of cases. ELS rarely has a bronchial connection with the normal respiratory tree, the trachea, or the digestive tract. In the latter case, the fistulous connection can be with the esophagus, or, more rarely, with the stomach [1, 4]. Lining with gastric mucosa, in such a case, has been reported [1].
In one case we observed a cystic ELS without connection with the bronchial tree or the gastrointestinal tract. Furthermore, CCAM lung tissue and gastric mucosa were observed, the lower part of which issued from the retroperitoneum through a small diaphragmatic hernia.
A 22-year-old female was admitted because of a right posterobasal cystic thoracic mass. Her past clinical history was negative except for recent recurrent episodes of fever with nonspecific cervical adenopathies regressing with antibiotic therapy. During the last episode of fever, a chest roentgenogram was performed demonstrating a right posterobasal thoracic mass. Computed tomography demonstrated the cystic nature of the mass, the lower part of which being located close to the diaphragm. Nuclear magnetic resonance demonstrated that the inferior part of the mass was located in the retroperitoneum, with most of the mass developing within the right pleural space through a small diaphragmatic defect (Fig 1).
Surgical exploration confirmed a cystic mass issuing from the retroperitoneum through the diaphragm. The mass was entirely covered by pleura. Dissection through the diaphragmatic defect evidenced its vascularization by systemic vessels: artery arising from branches of the aorta and vein draining into the inferior vena cava, all characteristics confirming an ELS. The mass was completely removed and the diaphragmatic defect sutured. Pathologic examination demonstrated complex cystic extralobar sequestration lined in its lower part (subdiaphragmatic part) by gastric epithelium with perfectly regular glandular structures (Fig 2A),
a mixed zone with gastric epithelium becoming ciliate epithelium with cartilage in the wall (Fig 2B), and in its apical portion canalar stage of fetal pulmonary-like tissue, similar to CCAM type II (Fig 2C): at this last level no smooth muscle was present. In this case, no tumor was observed and recovery was uneventful. The patient was faring well one year following surgery.
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Fig 1. Magnetic resonance imaging study. T2-weighted sagittal image demonstrating a fluid level within the juxtadiaphragmatic mass. Above all, the sequestration is issuing from the retroperitoneum through a small diaphragmatic defect (arrow)
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Fig 2. Pathologic examination. Histology (hematoxylin & eosin stain, original magnification x 200) demonstrating a complex extralobar sequestration: (A) lower part = gastric epithelium, (B) middle part = respiratory epithelium, (C) upper part = canalar stage of fetal pulmonary-like tissue.
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Comment
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The present case is an unusual type of ELS associating several rare characteristics, among which the discovery during adulthood, a right sided location, and the combination of several malformations. Malformations observed consisted of a diaphragmatic "hernia," subdiaphragmatic digestive component, and systemic vascularization with the presence of CCAM and gastric mucosa without digestive communication. The combination of these malformations suggests a common origin from the foregut.
The etiology of intralobar sequestration remains controversial, but ELS are commonly considered to be of congenital origin and are included in bronchopulmonary foregut malformations.
The respiratory system develops during the third week of embryonic stage from an outpouching laryngotracheal groove developing on the ventral face of the foregut, further dividing into right and left bronchi, bronchioles, and alveolar ducts [5].
The ELS develops (1) either from a separate outpouching of the foregut (supernumerary foregut lung bud formation) or (2) by separation of embryonic lung forming cells because of adhesion to other organs, which, by traction of differential growth, separates them from the remainder of the lung tissue [1, 5]. Thus, a separate pleura develops around the sequestration.
Sequestration must result from a secondary outpouching of the foregut in the cases in which an esophageal or gastric fistula is present [1, 4]. When ELS exists without a fistulous connection, the explanation resulting from adhesion is undoubtedly correct, and has been demonstrated experimentally [1]. Gastric mucosa in our case supports both theories.
Embryologically, CCAM represents a relatively late malformation in the development of the lung bud. This occurs before the fourth or fifth week after differentiation of terminal bronchioles has occurred [6]. The presence of CCAM within the extralobar sequestration supports the latter theory of ELS resulting from adhesion. Another explanation for the occurence of CCAM is focal pulmonary dysplasia or hamartoma, although the lesion observed is not composed of the intermixture of epithelium, cartilage, fat, and other tissues usually observed in the so-called "hamartoma" of the lung [6]. However, the high frequency of CCAM in extralobar sequestration is too important to be purely coincidental. Also, our case points out the possibility for CCAM to occur as a developmental anomaly within extralobar sequestration due to secondary pulmonary outgrowth of the foregut.
Nearly 50% of patients with ELS present within 24 hours of birth [3], but a significant number is also seen in adult life (16% 19-years-old or more [3]). In most cases, extralobar sequestration is asymptomatic and discovered incidentally [1, 7]. Diagnosis is assessed by demonstrating the origin of the arterial blood supply. Arterial blood supply may be demonstrated by both angiography and computed tomography [7]. In our patient, computed tomography failed to demonstrate systemic vascularization.
Regular clinical followup without surgery for patients with asymptomatic sequestration has been advocated [7]. However, a high incidence (48%) of rhabdomyomatous dysgenesis was observed in the case of ELS with CCAM [3] and rhabdomyosarcomas have been described by Carrasco and colleagues [4]. Furthermore, bronchioloalveolar carcinoma may develop within congenital cystic adenomatoid malformation itself [8]. As CCAM may be an important component of ELS with no diagnostic workup available, we believe surgery is advisable before the advent of serious complications.
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References
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- Skandalakis J.E., Gray S.W., Symbas P. Pulmonary circulation. In: Mitchell C.W., ed. Embryology for surgeons. The embryological basis for the treatment of congenital anomalies. Baltimore, MD: Williams and Wilkins, 1994:451-490.
- Savic B., Birtel F.J., Tholer W., Funke H.D., Knoche R. Lung sequestration: report of seven cases and review of 540 published cases. Thorax 1979;34:96-101.[Abstract/Free Full Text]
- Conran R.M., Stocker J.T. Extralobar sequestration with frequently associated congenital cystic adenomatoid malformation, Type 2: report of 50 cases. Ped Dev Pathol 1999;2:454-463.
- Carrasco R., Castañón M., San Vicente B., Tarrado X., Montaner A., Morales L. Extralobar infradiaphragmatic pulmonary sequestration with a digestive communication. J Thorac Cardiovasc Surg 2002;123:188-189.[Free Full Text]
- Stocker J.T., Kagan-Hallet K. Extralobar pulmonary sequestration: analysis of 15 cases. Am J Clin Pathol 1979;72:915-917.
- Hutchin P., Friedman P.J., Saltzstein S.L. Congenital cystic adenomatoid malformation with anomalous blood supply. J Thorac Cardiovasc Surg 1971;62:220-225.[Medline]
- Kristo D.A., Pluss J.L., Chantelois A. Asymptomatic Extralobar sequestration in a 43-year-old-woman. South Med J 1995;88:225-226.[Medline]
- Ribet M.E., Copin M.C., Soots J.C., Gosselein B.H. Bronchioalveolar carcinoma and congenital cystic adenomatoid malformation. Ann Thorac Surg 1995;60:1126-1128.[Abstract/Free Full Text]
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Abstract
Introduction
