Introduction

Bronchogenic cysts develop from tracheal diverticula or abnormal budding of the anterior foregut during embryological period. Their most common extrapulmonary location is mediastinum. However, remote locations such as lingual, intra-abdominal and cutaneous regions have also been reported [1]. Cutaneous bronchogenic cysts (CBC) are very rare lesions which are often diagnosed histopathologically. Moreover, scapular location comprise an infrequent form of this entity [2, 3].

Hereby, we aimed to describe a scapular bronchogenic cyst in a girl and review its clinical features with the previously reported cases.

Case report

An one-year-old girl was brought to our hospital with the complaint of a dark-green drainage at the back of her shoulder. Her complaints had been present for 8 months. In her physical examination, a hyperemic enduration with an orifice and purulent drainage was noted at the left scapular region (Fig. 1). All the other organ systems were normal. Initially the patient was followed-up clinically. Upon development of an abscess, drainage and antibiotic therapy were given and further diagnostic studies were planned. Purulent discharge lasting for 3–4 days in every 2 weeks went on during the follow-up. Ultrasonography revealed a lesion of 15×11 mm2 in size with a thick wall and a hypoechoic center. No connection with the thoracic cavity was seen. After the infection had resolved, the cyst was demonstrated with fistulography (Fig. 2). During the operation, the cystic mass, which was about 2×1 cm2 in size and with a thick wall, was totally excised. Pathological examination revealed a cystic lesion lined with ciliated pseudostratified columnar epithelium alternating with stratified squamous epithelium and mucous glands surrounded by chronic inflammatory tissue consistent with CBC. Her postoperative follow-up was uneventful.

Fig. 1
figure 1

General appearance of the sinus at the scapular region

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Fig. 2
figure 2

The microscopic appearance of the lesion (arrows epithelium, m mucous glands, H&E 40×)

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Discussion

Cutaneous bronchogenic cysts are very rare lesions that are mostly seen in children due to their congenital origin. About 64 cases have been reported in the literature so far. The most common location of these lesions are suprasternal notch, presternal area, neck and scapula [4].

There are two main embryological explanations for the development of CBC. The primitive tracheal structures develop at the fifth week of gestation. The left and right mesenchymal plates of the sternum close at the ninth week. In one theory, the bronchogenic cyst, which already exists, is accepted to be left out of the thorax after sternal closure and migrates to the cutaneous region. In another theory, the cyst simply pinches off from the developing tracheal bud during the closure of the mesenchymal plates [5, 6]. Except for a few cases, no connections have been found between the cyst and the thorax in CBC cases [3]. In two scapular locations there has been a connection to the scapula [2, 7]. As the lesions are mostly solitary without a connection including our case, “the pinch-off theory” seems to explain the situation in most of the cases. However, the exact mechanism is yet to be determined.

The pathological diagnosis is made with the demonstration of one or more tracheobronchial structures in the cyst wall. In most cases, hyaline cartilage, smooth muscle cells, elastic fibers, fibrous tissues, neural cells and seromucous glands can be seen [5, 7]. The surface epithelium is usually ciliated pseudostratified columnar or cuboidal cells but in conditions of chronic infections these structures may be changed and lymphoid follicules may be seen [7]. Stratified squamous epithelium can be seen in 2% of CBC cases and it is a frequent finding in branchial cysts [4]. Anatomical location of the cyst in our patient was inconsistent with branchial arch anomalies and the diagnosis was confirmed with the demonstration of ciliated pseudostratified columnar epithelium and mucous glands in the wall of the cyst.

Scapular CBC are very rare cutaneous lesions which are mostly seen in children. Together with the three CBC cases that we have experienced in our clinics, 2 presternally located, 1 of which was reported in a local journal [1] and this present case, out of 67 CBC patients, in 12 of them (17.9%) the anatomical location was scapular (Table 1). Out of the 12 scapular CBC, only 2 cases are females. These lesions have the same male preponderance as other locations of CBC. Nine of the cases (75%) were diagnosed before the age of 4. In Fraga’s study, which is the largest patient collection of CBC, 12 out of 30 patients (40%) were diagnosed before 4 years of age [7]. These cysts can be diagnosed as slowly growing masses or draining sinuses [8]. A mass over the scapula is the most common complaint in the scapular CBC patients. The explanation of early recognition may be the anatomical location itself as the scapular region is relatively bare when compared with the other locations.

Table 1 The details of the scapular CBC patients in the literature
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The treatment of choice for all CBC as well as scapular lesions is surgical excision due to the potential risk of infection, as experienced in our case, and malignant degeneration, which has been reported in a scapular bronchogenic cyst [9]. In the differential diagnosis of scapular CBC, lymphangioma, epidermal cysts, sebaceous cysts and aneurysmal bone cysts should be ruled out [5, 7, 10].

Scapular CBC have been evaluated from the dermatological and pathological point of view in most of the studies in the literature. Pediatric surgeons should also be familiar with this entity as the clinical admission may be directed to a pediatric surgical clinic as well. The diagnosis is histopathological in most of the cases. Thus, early recognition can be achieved with a detailed understanding of the pathology.