Dermatology

Bronchogenic Cysts

Are You Confident of the Diagnosis?

What you should be alert for in the history

Cutaneous bronchogenic cysts (CBC) are very rare benign congenital developmental abnormalities of the tracheobronchial tree. Preoperative diagnosis is difficult, and accurate diagnosis requires histopathologic examination of the lesion.

Characteristic findings on physical examination

A child presenting with an asymptomatic neck mass located above the sternal notch is the most typical clinical presentation. The vast majority of the cases are diagnosed in the pediatric age group with a few cases reported in adults. Whereas most CBCs are asymptomatic, patients can present with draining sinuses, cyst enlargement and/or tenderness.

Physical examination reveals an asymptomatic solitary cystic neck nodule or mass, most commonly in the anteromedial neck, the suprasternal notch and presternal area, followed by the neck and scapula. Most are noted at birth as solitary nodule or cyst and usually enlarge with body growth.

Expected results of diagnostic studies

Laboratory studies are rarely necessary in the workup of cutaneous bronchogenic cysts as the diagnosis relies on histology. Given its scarcity, it is often misdiagnosed clinically, and a definitive diagnosis requires histopathologic confirmation. The characteristic histologic finding is the presence of a unilocular cystic lesion in the dermis or subcutaneous tissue lined by respiratory ciliated pseudostratified columnar epithelium and a fibrous connective tissue wall containing smooth muscle cells, mucin-containing goblet cells and less frequently, cartilage (Figure 1).

In case of prior infection, squamous epithelium may be found. The cyst may contain debris and seromucinous secretions. Demonstration of one or more tracheobronchial structures in the cyst wall is helpful in making the histologic diagnosis. The presence of cartilage, although not a prerequisite for the diagnosis, is a highly characteristic histologic finding.

The most important entity in the histologic differential diagnosis is branchial cyst. The presence of lymphoid tissue and stratified squamous epithelial lining in branchial cysts are the most important histologic distinguishing features between these lesions.

Imaging studies are valuable in determining the size, shape and position of the cyst in relation to the adjacent anatomic structures. Classic bronchial cysts primarily affect the tracheobronchial tree, usually located in the mediastinum and intrapulmonary regions. Cutaneous bronchogenic cysts are extremely rare.

Conventional 2-view chest radiography typically shows a sharply demarcated spherical mass of variable size. When the cyst is infected, it may appear as a solid tumor or demonstrate an air fluid level. Chest computed tomography (CT) scan shows a cystic, non-enhancing, well-circumscribed lesion with thin wall, usually fluid-filled as it may contain secretions, pus or blood. MRI is the study of choice due to its excellent soft-tissue detail.

Diagnosis confirmation

Cutaneous bronchogenic cysts are poorly recognized by clinicians and sometimes confused with other congenital neck cysts, therefore anatomic location and histology are crucial in the differential diagnosis.

The differential diagnosis includes the following entities:

  1. Branchial cleft cyst (most commonly confused with bronchogenic cysts, distinguished by location higher and laterally on the side of the neck and characteristic histology showing a cyst lined by stratified squamous epithelium, lymphoid tissue with germinal centers, absence of cartilage and smooth muscle);

  2. Thyroglossal duct cysts (differentiated by anatomic location, involving the midline on the anterior aspect of the neck, in close proximity to the hyoid bone, they move up with protrusion of the tongue, and histology resembles thyroid tissue; thyroid follicles are frequently present;

  3. Dermoid cyst (most frequently located along embryonic closure lines, especially on the head, histologically characterized by a cyst wall lined by keratinizing stratified squamous epithelium containing skin appendages);

  4. Cystic hygroma (affects the head and neck, especially the posterior triangle; histology shows large cavernous spaces lined by flat endothelial cells, considered a variant of lymphangioma);

  5. Epidermal inclusion cyst (anywhere on the body, a central punctum may be present; distinctive histology showing stratified squamous epithelial lining),

  6. Trichilemmal cyst (predilection for the scalp; the lining of the cysts is squamous epithelium without granular cell layer and abrupt trichilemmal keratinization).

  7. Ciliated cyst is another cystic lesion that could be considered in the differential diagnosis (affectIng the lower extremities of young women, the cyst lining is ciliated columnar epithelium with papillary projections, resembling Fallopian tube).

Who is at Risk for Developing this Disease?

Cutaneous bronchogenic cyst is a very rare developmental abnormality of the tracheobronchial tree with only 86 cases reported in the literature. It is most commonly diagnosed in the pediatric population and 50% of these cysts are noted at birth.

They are 4 times more common in men than in women. There are no known risk factors predisposing for the development of cutaneous bronchogenic cysts.

What is the Cause of the Disease?

Etiology

Pathophysiology

Bronchogenic cysts are congenital developmental abnormalities of the tracheobronchial tree. The precise embryogenesis is unclear but they are thought to arise from maldevelopment of the embryonic foregut leading to abnormal bronchial budding and malformations of the distal tracheobronchial tree.

Bronchogenic cysts can be intra- or extrathoracic. Intrathoracic cysts are more common and are found in the anterior mediastinum and lung and may remain connected to the tracheobronchial airway by either a fibrous cord or a patent bronchus-like connection.

In the absence of an attachment, bronchogenic cysts can migrate and occasionally become displaced, explaining the remote extrathoracic locations, including cutaneous bronchogenic cysts, that can present in the suprasternal notch, presternal area, neck, and infraclavicular region.

Systemic Implications and Complications

Pulmonary and extrapulmonary mediastinal bronchogenic cysts via mass effect can compress vital structures, cause airway compromise and respiratory distress, secondary infection, rupture, bleeding and rarely, malignant transformation. Carcinomas (such as mucoepidermoid carcinoma) arising from bronchogenic cysts have been very rarely reported

In contrast, cutaneous bronchogenic cysts are usually asymptomatic. Occasionally, if left untreated, secondary infection may occur resulting in tenderness, sinus tract formation and drainage of purulent material if the cyst is superficial or abscess formation of the cyst is deep. Recurrence of an incompletely excised cutaneous bronchogenic cyst can occur.

Treatment Options

Complete surgical resection of all bronchogenic cysts is recommended due to potential risk of infection and rare reports of malignant degeneration.

Optimal Therapeutic Approach for this Disease

The treatment of choice is complete surgical excision, which is both diagnostic and therapeutic. It is essential that the cyst is removed completely to reduce the risk of recurrence. A neck exploration and selective dissection is the surgical approach of choice. The great vessels and recurrent laryngeal nerve are exposed to risk during surgery.

If a draining sinus is present in association with the cyst, both the sinus tract and the cyst should be excised.

Patient Management

Explain to the patient the nature of the lesion, which if left untreated, can lead to complications, including fistulization, hemorrhage, infection and growth over time. Discuss with the patient the need for surgical excision given the minimal but existent risk of infection and malignant degeneration.

Inform the patient that late recurrences may occur in those who undergo partial resection; therefore, long-term follow-up is needed to detect possible recurrences. If complete surgical excision is performed, recurrence is unlikely.

Unusual Clinical Scenarios to Consider in Patient Management

Remember that although the most frequent anatomic location of cutaneous bronchogenic cyst is the presternal area and neck, unusual locations such as the chin can occur.

What is the Evidence?

Zvulunov, A, Amichai, B, Grunwald, MH, Avinoach, I, Halevy, S. "Cutaneous bronchogenic cyst: delineation of a poorly recognized lesion". Pediatr Dermatol. vol. 15. 1998. pp. 277-81.

(Case report of a bronchogenic cyst with an unusual clinical presentation in a 4-year-old girl and review of the literature with respect to characteristic clinical and histologic features. This paper emphasizes that bronchogenic cysts should be included in the differential diagnosis of congenital cystic skin lesions on the upper trunk and neck.)

Newkirk, KA, Tassler, AB, Krowiak, EJ, Deeb, Z. "Bronchogenic cysts of the neck in adults". Ann Otol Rhinol Laryngol. vol. 113. 2004. pp. 691-5.

(This is a case report of two adult patients with bronchogenic cysts presenting as solitary neck masses. The authors provide a review of the literature with emphasis on the histopathologic and clinical characteristics of bronchogenic cysts and discussion of the features that distinguish them from other cervical cysts.)

Elder, D, Elenitsas, R. "Atlas and synopsis of Lever's histopathology of the skin". Lippincott Williams & Wilkins. 2010. pp. 450.

(Description of the characteristic histopathologic features of bronchogenic cysts.)

Calb, IL, Haas, E, Lewandowski, MG, Maler, L. "Cutaneous bronchogenic cyst: an unusual localization and review of the literature". Br J Dermatol. vol. 143. 2000. pp. 1353-5.

(This is a case report of a cutaneous bronchogenic cyst located on the chin, an unusual localization of this lesion and a detailed review of the literature, including prior reports, etiology and lesions that should be considered in the differential diagnosis.)

Fraga, S, Helwig, EB, Rosen, SH. "Bronchogenic cysts in the skin and subcutaneous tissue". Am J Clin Pathol. vol. 56. 1971. pp. 230-8.

(This is the largest series of cutaneous bronchogenic cysts. The authors report 30 cases of such lesions, discussing the characteristic clinical and histologic features of this entity.)

Shah, SK, Stayer, SE, Hicks, MJ, Brandt, ML. "Suprasternal bronchogenic cyst". J Pediatr Surg. vol. 43. 2008. pp. 2115-7.

(This is a case report of a 23-year-old patient with a midline suprasternal bronchogenic cyst and a brief review of the literature.)

Tanaka, M, Shimokawa, R, Matsubara, O, Aoki, N, Kamiyama, R, Kasuga, T. "Mucoepidermoid carcinoma of the thymic region". Acta Pathol Jpn. vol. 32. 1982. pp. 703-12.

(This is a case report of mucoepidermoid carcinoma arising from a cyst in the thymic region, the histology of which was consistent with bronchogenic cyst origin.)

Patterson, JW, Pittman, DL, Rich, JD. "Presternal ciliated cyst". Arch Dermatol. vol. 120. 1984. pp. 240-2.

(This is a case report of a presternal ciliated cyst in a 39-year-old man. The location and histologic features of this lesion were consistent with bronchogenic cyst.)

Jona, JZ. "Extramediastinal bronchogenic cysts in children". Pediatr Dermatol. vol. 12. 1995. pp. 304-6.

(Report of three children with extramediastinal bronchogenic cysts who presented with subcutaneous masses that were histologically proven to represent subcutaneous bronchogenic cysts.)

Militsakh, O, Manaligod, JM. "Pathology quiz case 1. Cervical bronchogenic cyst". Arch Otolaryngol Head Neck Surg. vol. 127. 2001. pp. 1390-1392.

(This is a pathology quiz case of an 8-year-old boy presenting with a slow-growing, asymptomatic neck mass left of the thyroid gland. The authors discuss the embryological origin of bronchogenic cysts.
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