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Chin Med J (Taipei) 1997;59:311-4.
1Section of Pathology, Pingtung Christian Hospital, Pingtung, and 2Department of Pathology; 3Section of Urology, Department of Surgery, Veterans General Hospital-Kaohsiung, Kaohsiung, Taiwan, R.O.C.
Only a few subdiaphragmatic bronchogenic cysts are described, and their occurrence in the retroperitoneum is extremely rare. So far, only a few cases have been reported in the English-language literature. The pathogenesis is caused by the pinching off of irregular lung budding of the primitive ventral foregut, with aberrant migration into the abdomen before fusion of the diaphragm during embryonal development. A unique case with clinical, radiographic, surgical finding is presented. Final pathological findings confirmed the diagnosis of retroperitoneal bronchogenic cyst without other associated congenital anomalies. Retroperitoneal bronchogenic cyst, although rare, should be considered in the differential diagnosis in the retroperitoneal mass. This rare case is described and the relevant literature, reviewed.
[Chin Med J (Taipei) 1997;59:311-4.]
Keywords: bronchogenic cyst, retroperitoneum
Received: October 18, 1996.
Accepted: March 11, 1997.
Address reprint requests to: Shih-Peng Hsieh, MD, Section of Pathology, Pingtung Christian Hospital, 60, Ta-Lian Road, Pingtung, Taiwan 900, R.O.C.
Bronchogenic cysts are primitive foregut-derived developmental anomalies most commonly encountered in the mediastinum [1-3], and rarely in the abdomen [4-7], according to the English-language literature. They most frequently occur in the posterior portion of the mediastinum, but have reportedly appeared occasionally elsewhere, such as in the skin and subcutaneous tissue [8], pericardium [9] and intradiaphragm [10]. Histologically, bronchogenic cyst is composed of respiratory epithelium, smooth muscle, mixed serous and mucous respiratory glands and cartilage, just as seen in normal bronchi.
To date, only a few cases of retroperitoneal bronchogenic cysts have been reported [2,5,11,12]. The present report describes an additional unique case of retroperitoneal bronchogenic cyst and reviews the relevant literature.
A 24-year-old female was asymptomatic clinically, but was told she had a left adrenal tumor, found by abdominal sonography during a healthy physical check-up in a local medical clinic about six months prior to this admission. During admission here, she denied history of headache, dizziness, or flushing. Blood pressure was normal. A series of blood biochemistry and urine analysis studies were unremarkable. Plasma catecholamine test and cortisol levels were within normal limits. On physical examination, the patient exhibited no clinical manifestation of Cushing's syndrome. No mass could be palpated in her left flank region. Abdominal computed tomography scan revealed a soft tissue mass, 3 cm in diameter, in the left adrenal bed (Figure 1). A magnetic resonance imaging study was performed, and a 3-cm soft tissue mass in the left adrenal gland was identified, with high signal intensity on T2WI. GE in-phase and out-phase image revealed about 30 units difference, consistent with adenoma-group of the adrenal gland (Figure 2). Thus the patient underwent an operation under the impression of a left adrenal tumor. At operation, the left adrenal gland showed no remarkable change. However, an isolated cystic lesion in the left para-vertebral area near the left adrenal gland was identified, showing no connection with surrounding soft tissue and visceral organs. Excision of the lesion was performed.
Grossly, the removed cyst was measured 2.5 x 1.5 x 1.0 cm in size and showed multicystic feature with turbid contents. Microscopically, the cyst was lined by pseudostratified ciliated columnar epithelium. The cyst wall was composed of mixed serous and mucous respiratory glands, smooth muscle, and cartilage (Figures 3 and 4). The characteristic features, similar to those of normal bronchi, but with absence of teratomatous components, confirmed the pathological diagnosis of bronchogenic cyst.
Bronchogenic cysts are rare abnormalities of the ventral foregut. The majority of these lesions occur above the diaphragm, mainly in the mediastinum [1-3] and, less commonly, in the intrapericardium [9]. They can also occur in other unusual sites such as in skin and subcutaneous tissue [8], intradiaphragm [10] and intra-abdomen [2,4-6,11,12].
Most reported subdiaphragmatic bronchogenic cysts have been located in the peritoneal cavity, and have demonstrated an attachment to the gastrointestinal tract, usually in the stomach [2,4-6]. To date, it has been possible to find only a few case reports of retroperitoneal bronchogenic cysts [2,5,11,12] in the English-language literature; of these, two cases manifested adrenal mass pre-operatively, similar to the case described here. The histology in these cases share both gross and microscopic similarities to counterparts in the mediastinum, revealing simple columnar or pseudostratified ciliated lining epithelium which is surrounded by smooth muscle, seromucous respiratory glands and cartilage... components similar to those in normal bronchi. As mentioned by Sumiyoshi et al. [5], such an unusual location could arise from the pinching off of an abnormal budding of the primitive ventral foregut in the ensuing development of the lung with aberrant migration into the abdomen before fusion of the diaphragm during embryonal development, resulting in a subdiaphragmatic bronchogenic cyst, bronchopulmonary sequestration and tracheal lobe. Another less likely alternative hypothesis explained aberrant differentiation of foregut-derived cysts originating intraabdominally [2].
The differential diagnosis of a retroperitoneal cyst lined with pseudostratified ciliated columnar epithelium includes intra-abdominal teratoma, bronchopulmonary sequestration, cyst of urogenital origin, and intra-abdominal esophageal cyst [7] in addition to bronchogenic cyst. The presence of orderly arranged components of normal bronchi without other elements of a teratoma can clearly help to rule out the diagnosis of teratoma. Bronchopulmonary sequestration, although believed to share a common embryologic origin with bronchogenic cyst [5], can also be excluded in the absence of lung parenchyma and the invested pleural tissue along with bronchial elements. The mixed serous and mucous glands in this present case are not seen in retroperitoneal cysts of urogenital origin. Both intra-abdominal esophageal cyst, as reported by Harvell et al. [7] recently, and bronchogenic cyst, may have the same ciliated epithelium. However, the absence of two smooth muscle layers, along with the presence of cartilage and respiratory seromucous glands, allows a definite pathological diagnosis of bronchogenic cyst.
Both Swanson et al. [11] and Foerster et al. [12] described a bronchogenic cyst interpreted to be an adrenal mass by abdominal sonography, computed tomography, and magnetic resonance imaging studies preoperatively, the same as in this present case. Definite diagnosis should be confirmed by the characteristic pathological features. Retroperitoneal bronchogenic cyst, a developmental anomaly of ventral foregut, although rare, should be considered among differential diagnoses of retroperitoneal mass.
Copyright: 1997, Chinese Medical Association (Taipei)