Bronchogenic cyst overview

# Overview
Bronchogenic cyst is a rare benign congenital malformation of the tracheobronchial tree derived from the ventral aspect of the foregut. It most frequently occurs in the middle mediastinum, in the early stages of gestation or in the lungs, at the later stages of gestation. Atypical locations may be explained by its embryologic origin. 
Patients with bronchogenic cyst may be asymptomatic or present with respiratory distress, increasing stridor,  feeding difficulties, chest pain, cough, progressive dysphagia, odynophagia, purulent sputum, dyspnea, anorexia and/orweight loss.
Radiologic findings are useful to differentiate bronchogenic cysts from other cysts but they may not always confirm the diagnosis. Diagnosis is confirmed by surgical excision, which is curative, and histological findings of ciliated columnar epithelial lining of the cyst.

# Historical Perspective
There is limited information about the historical perspective of bronchogenic cyst.

# Classification
Bronchogenic cyst can be classified based on location; pulmonary and extrapulmonary.

# Pathophysiology
It is thought that bronchogenic cyst is the result of abnormal budding of the ventral portion of the primitive foregut between days 26 - 40 of  gestation.

# Causes
The cause of bronchogenic cysts is undetermined.

# Differentiating Bronchogenic cyst from other Diseases
Differentiating bronchogenic cyst from lung abcess, thymic cyst, and esophageal duplication cysts.

# Bronchogenic cyst epidemiology and demographics|Epidemiology and Demographics
There is no racial predilection to bronchogenic cyst. Bronchogenic cyst is slightly more prevalent in men and often remain undetected until the third or fourth decade of life.

# Risk factors
There are no established risk factors for bronchogenic cyst.

# Screening
There is insufficient evidence to recommend routine screening for bronchogenic cyst as it is usually an incidental finding.

# Natural history, complications and prognosis
Natural History
The symptoms of bronchogenic cyst usually develop in the third to fourth decade of life and start with symptoms such as
- Dyspnea
- Chronic dry cough
- Rhinitis
- Chest discomfort/pain
- Neck pain
- Flu-like symptoms and Fever
- Purulent sputum
- Abdominal discomfort
- Limb weakness
- Paroxysmal supraventricular tachycardia
- Atrioventricular block
- Memory impairment
- Asthenia
- Seizure and loss of consciousness
- Dizziness
- Lower back pain
- Urinary incontinence
Complication
Common complications of bronchogenic cyst include
- Tracheal compression
- Esophageal compression
- Cough
- Infection/abscess
- Hemoptysis
- Superior vena cava syndrome
- Pneumothorax
- Pleurisy
- Pneumonia
- Lymphangioma
- Haemorrhage
- Neoplasia(adenocarcinoma, mucoepidermoid carcinoma,  anaplastic carcinoma, and leiomyosarcoma)
- Rupture
- Air embolism
- Cardiac tamponade
- Ventricular septal defect
- syringomyelia
Prognosis
Prognosis is generally good, a Morbidity & Mortality rate of 20% has been recorded in older patients treated for bronchogenic cyst.

# Diagnostic Study of Choice
Excision and Hematoxylin and Eosin staining.
Cillated columar epithelia cells is definitive for broncogenic cyst.

### Diagnostic criteria
Cystic mass-producing compressive symptoms.

# History and symptoms
The majority of patients with bronchogenic cyst  are asymptomatic and are diagnosed during investigations for other pathologies.
When symptomatic, the clinical presentation of bronchogenic cyst depends on the age of the patient, size and the location of the cyst.
In infants bronchogenic cyst presents with
- respiratory distress
- Increasing stridor
- Reccurrent croup
- Feeding difficulties.
- Palpable neck mass
- Non-bilious emesis
In children and adults, bronchogenic cyst presents with
- Dull chest pain with radiation to the shoulder in diaphragmatic broncogenic cyst.
- Cough
- Progressive dysphagia
- Odynophagia
- wheezing
- Adobminal bloating
- Fever
- Palpable neck mass
- purulent sputum
- Hemoptysis
- Dyspnea
- Anorexia and/or weight loss
- Dizziness
- Paroxysmal supraventricular tachycardia
- Atrioventricular block
- Atrial and ventricular premature complexes
- Memory impairment
- Asthenia
- Limping
- Seizure and loss of consciousness
- Sciatica
- Back pain
- Neuralgia
- Urinary incontinence

# Physical examinaton
Physical examination of patients with bronchogenic cyst is usually normal. On rare occasions, the following signs can be seen
- Cough
- wheezing
- Stridor
- Hemoptysis
- Dyspnea
- Tracheal deviation
- Fluid-thrill
- Anorexia and/or weight loss
- Fever
- Asthenia
- Foot drop
- Atrophy
- Heart murmur
- Tenderness
- Cutanous pigmentation
- Negative knee and ankle reflexes
- Numbness

# Laboratory findings
An elevated serum tumor makers CA125 and CA19-9, which is usually suggestive of progression/complication.

# CT
CT scan may be helpful in the diagnosis of bronchogenic cyst. The density of bronchogenic cysts is variable from water density to high density due to blood, anthracotic pigment, increased calcium content, or increased protein content of the fluid. Findings on CT scan suggestive of bronchogenic cyst is an
- Cysic mass with air-fluid levels.
- ovoid and well-defined encapsulated low-density cystic mass with no contrast enhancement.
- Thin subtle walls.

# MRI
MRI may be helpful in the diagnosis of bronchogenic cyst. After contrast injection, enhancement of the cyst is frequently absent. Findings on MRI suggestive of bronchogenic cyst include
- T1-weighted images show ipointense signal
- T2-weighted images show hyperintense signal.

# Ultrasound
ultrasound may be helpful in the diagnosis of bronchogenic cyst. Finding on an ultrasound suggestive of bronchogenic cyst include
- On endobronchial ultrasound, an anechoic or hypoechoic fluid-filled solid mass.
- On transthoracic echocardiography revealing intracardiac cystic mass.
- On endoscopic ultrasonography, which demonstartes abdominal anatomic relations of the cyst.

# Other Diagnostic Studies
Other diagnostic studies for bronchogenic cyst include:
Excision and Hematoxylin and Eosin staining, which demonstrates ciliated columar epithelia cells is definitive for bronchogenic cyst
- Immunohistochemical staining of bronchogenic cyst of the esophagus , which demonstrates a positive expression of CA199 and CA125.
- Bronchoscopy, which demonstrates pink cystic mass with bronchial attachment
- Gastroendoscopy which demonstartes abdominal anatomic relations of the cyst.
- fluorodeoxyglucose-positron emission tomography to confirm cyst infection.

# Treatment

## Medical therapy
The mainstay of treatment for bronchogenic cyst is surgery.

## Surgery
Surgery is the mainstay of treatment for bronchogenic cyst even when the patients are asymptomatic, a conservative approach is not approved.

# Primary prevention
There are no established measures for the primary prevention of bronchogenic cyst.

# Secondaryy prevention
There are no established measures for the secondary prevention of bronchogenic cyst.