207

The Korean Journal of Pathology 2010; 44: 207-10DOI: 10.4132/KoreanJPathol.2010.44.2.207

We report here on a case of a rare, complex bronchopulmonary foregut malformation (BPFM)that was composed of an extralobar pulmonary sequestration communicating with an eso-phageal duplication cyst. A 33-year-old female presented with an incidentally detected chestmass. The computed tomography revealed a 7.5 × 4.0 cm sized heterogeneous, solid andcystic lesion in the right superior mediastinum. Surgical resection demonstrated the solid por-tion to be isolated lung tissue invested in its own pleura. A unilocular cyst was communicat-ing with the bronchus of the sequestrated lung, and microscopically the cyst was lined bysquamous epithelium overlying the thick layers of smooth muscle. This case is important forunderstanding the spectrum of BPFMs and for differentiating a mediastinal mass, especiallyone at the unusual location.

Key Words : Bronchopulmonary sequestration; Esophageal cyst

Soyoung Im Sun Mi LeeJi Han Jung Jinyoung YooKyu Do Cho1 Seok Jin KangKyo Young Lee

207

Complex Bronchopulmonary Foregut Malformation: Extralobar Pulmonary

Sequestration Communicating with an Esophageal Duplication Cyst

- A Case Report -

Bronchopulmonary foregut malformations (BPFMs) encom-pass a broad spectrum of anomalies that may arise from abnor-mal differentiation of the respiratory and alimentary tracts dur-ing early embryogenesis.1 We report here on a rare case of com-plex bronchopulmonary foregut malformation that consisted ofan extralobar pulmonary sequestration associated with an eso-phageal duplication cyst.

CASE REPORT

A 33-year-old female presented with a chest lesion that wasincidentally discovered on a chest X-ray during a routine exami-nation. Computed tomography (CT) revealed a 7.5 × 4.0 cmsized heterogeneous mass located in the right superior medi-

astinum and it was abutting the trachea (Fig. 1). The anteriorportion of the mass appeared to be solid with vascular struc-tures within the mass, whereas the posterior portion had a cys-tic appearance, suggesting a mediastinal tumor. The patientunderwent an open thoracotomy with excision of the mass.

On gross examination, the solid portion of the lesion wasrevealed to be isolated lung tissue invested in its own pleura. Aunilocular cyst was filled with mucus and it communicatedwith the bronchus of the sequestrated lung (Fig. 2). On micro-scopic examination, the lung parenchyma was covered by vis-ceral pleura and it showed mature alveolar spaces filled withproteinaceous fluid (Fig. 3A). The cyst was lined by squamousepithelium and layers of smooth muscle with no cartilage. Thelining demonstrated an abrupt transition to respiratory epithe-lium with overlying cartilage plates at the neck portion, where

207 207

Corresponding AuthorJinyoung Yoo, M.D.Department of Pathology, The Catholic University ofKorea College of Medicine, 93-6 Ji-dong, Paldal-gu,Suwon 442-723, KoreaTel: 031-249-7593Fax: 031-244-6786E-mail: jinyyoo@catholic.ac.kr

Departments of Pathology and1Thoracic and Cardiovascular Surgery,The Catholic University of KoreaCollege of Medicine, Seoul, Korea

Received : March 5, 2009Accepted : August 18, 2009

208 Soyoung Im Sun Mi Lee Ji Han Jung, et al.

Fig. 3. (A) The lung parenchyma shows mature alveolar spaces filled with proteinaceous material. (B) The bronchus of the sequesteredlung demonstrates ciliated pseudostratified columnar epithelium with overlying cartilage plates. (C) There is an abrupt transition of therespiratory epithelium to squamous epithelium at the neck portion where the bronchus of the sequestrated lung is connected to the cyst.(D) The unilocular cyst is lined by squamous epithelium overlying thick layers of smooth muscle. No cartilage is found.

C D

A B

Fig. 1. Chest computed tomography reveals a 7.5 × 4.0 cm sizedheterogeneous mass in the right superior mediastinum. The ante-rior portion of the mass (S) appears to be solid with vascular struc-tures within the mass. The posterior portion (C) has a more cysticappearance. The communication (arrow) between these two por-tions is noted.

Fig. 2. (A) Gross examination reveals that the solid portion of themass is isolated lung tissue invested in its own pleura. (B) On thecut section, a unilocular cyst (arrowheads) is communicating withthe bronchus (arrow) of the sequestrated lung.

▶ ◀

AS08-4929 60 70 8090 100 140 B40 50 90

Extralobar Pulmonary Sequestration Communicating with an Esophageal Duplication Cyst 209

the cyst was connected to the bronchus of the sequestratedlung (Fig. 3B-D). The lesion was diagnosed as a BPFM, whichwas composed of an extralobar pulmonary segment that com-municated with an esophageal duplication cyst. A retrospectivereview of the previous CT revealed a small aberrant artery alongthe medial side of the cystic component and it originated fromthe thoracic aorta.

The patient’s postoperative course was uneventful and shehas done well during six months of follow-up.

DISCUSSION

Pulmonary sequestration is defined as a portion of lung tis-sue that has no identifiable communication with the normalbronchial tree and this lung tissue receives its blood supply fromone or more anomalous systemic arteries. Pulmonary sequestra-tions are divided into two types; extralobar pulmonary sequestra-tion has a distinct pleural covering that maintains completeanatomical separation from the adjacent normal lung tissue,whereas intralobar sequestration is embedded in the normallung.2 There have been many theories for the etiology of seques-tration, including vascular insufficiency, vascular traction andpost-infectious change.2,3 However, it is now widely acceptedthat pulmonary sequestration results from an embryologicmalformation of the lung bud and this may be associated withother congenital anomalies.

BPFM was first introduced by Gerle et al.4 in 1968 as thepulmonary sequestration with a patent communication to thegastrointestinal tract. Normally, at five weeks of embryonicage, a primitive diverticulum arises from the ventral aspect ofthe pharynx and grows caudally. Two lateral ridges form betweenthe diverticulum and the dorsal foregut, and they eventually fuseto become the tracheoesophageal septum, which divides theventral respiratory laryngotracheal tube from the dorsal esopha-gus. A primitive lung bud develops at the caudal end of thelaryngotracheal tube. By seven weeks, it bifurcates into two bron-chopulmonary buds, which become the right and left lungs.1,5

BPFM occurs during this stage as a variety of anomalies that arisefrom a supernumerary lung bud from the primitive foregut.Which type of BPFM develops depends on 1) the stage ofembryologic development when the accessory tissue arises, 2)the direction in which the aberrant pulmonary tissue grows and3) the retention or involution of the communication betweenthe accessory lung tissue and the parent viscus.6 If the accessorylung bud arises before development of the pleura, then it is

embedded in the adjacent normal lung tissue and it becomesan intralobar sequestration. If it develops late after the pleurahas been already formed, then it is invested in its own pleuraand forms an extralobar sequestration. Esophageal duplicationcysts result from the abnormal budding of the dorsal primitiveforegut during the same period of embryogenesis as that forbifurcation of the lung bud, and so esophageal duplicationcysts are believed to have a close relationship with extralobarpulmonary sequestration.7,8 In the present case, the bronchus ofthe sequestrated lung communicated with the esophagealduplication cyst, but not with the normal tracheobronchial treeor normal gastrointestinal pathway. This explains the absenceof any symptoms, and it also supports the theory of commonembryogenesis for the spectrum of BPFMs.1

Extralobar pulmonary sequestration communicating with aforegut cyst is very rare.1,6,7,9,10 Only three Korean cases havebeen reported in the medical literature: two with a duplicationcyst of the mixed bronchogenic and esophageal type, and onewith a tubular esophageal duplication.6,7,9 We have presented arare case of BPFM that was composed of an extralobar pul-monary sequestration communicating with an esophageal dupli-cation cyst. This lesion was radiologically considered to be atumorous condition prior to surgery because of its unusuallocation. Thus, BPFM should be included in the differentialdiagnosis of a mediastinal mass.

REFERENCES

1. Heithoff KB, Sane SM, Williams HJ, et al. Bronchopulmonary

foregut malformations: a unifying etiological concept. AJR Am J

Roentgenol 1976; 126: 46-55.

2. Corbett HJ, Humphrey GM. Pulmonary sequestration. Paediatr

Respir Rev 2004; 5: 59-68.

3. Park SH, Chi JG. Congenital bronchopulmonary foregut malfor-

mation: analysis of the surgical and autopsy cases. Korean J Pathol

1993; 27: 459-67.

4. Gerle RD, Jaretzki A 3rd, Ashley CA, Berne AS. Congenital bron-

chopulmonary-foregut malformation: pulmonary sequestration

communicating with the gastrointestinal tract. N Engl J Med 1968;

278: 1413-9.

5. Leithiser RE Jr, Capitanio MA, Macpherson RI, Wood BP. “ Commu-

nicating” bronchopulmonary foregut malformations. AJR Am J

Roentgenol 1986; 146: 227-31.

6. Kim KW, Kim WS, Cheon JE, et al. Complex bronchopulmonary

foregut malformation: extralobar pulmonary sequestration associ-

ated with a duplication cyst of mixed bronchogenic and oesophageal

type. Pediatr Radiol 2001; 31: 265-8.

7. Eom DW, Kang GH, Kim JW, Ryu DS. Unusual bronchopulmonary

foregut malformation associated with pericardial defect: broncho-

genic cyst communicating with tubular esophageal duplication. J

Korean Med Sci 2007; 22: 564-7.

8. Kiral H, Tezel CS, Kosar A, Keles M. Clinicopathologic demonstra-

tion of complex bronchopulmonary foregut malformation. Ann

Thorac Surg 2008; 85: 2114-6.

9. Lee S, Lee J, Park JH, Kim YW, Yang MH, Shin DW. Extralobar

pulmonary sequestration with an associated cyst of mixed bron-

chogenic and esophageal type: a case report. J Korean Med Sci

1997; 12: 567-9.

10. Yasufuku M, Hatakeyama T, Maeda K, Yamamoto T, Iwai Y. Bron-

chopulmonary foregut malformation: a large bronchogenic cyst

communicating with an esophageal duplication cyst. J Pediatr Surg

2003; 38: e2.

210 Soyoung Im Sun Mi Lee Ji Han Jung, et al.