Bronchogenic Cysts.

 

Bronchogenic Cysts

PKGhatak, MD

Bronchogenic cysts are rare in adults but not so uncommon in newborns and young children. In a 3 to 6 week old fetus, two independent lateral lung buds develop as outpouchings from the ventral wall of the primitive foregut. (1).  Each of these two lateral buds differentiates as right and left main bronchi. The primitive foregut differentiates into the trachea and esophagus by developing a deep groove and joining the laryngotracheal sulci of the lateral wall of the foregut. Each main bronchi rapidly grows in the surrounding mesenchymal tissue and branches repeatedly and forms the rest of the conductive airways. Bronchogenic cysts arise from the development errors of the bronchogenic cells. Some of the bronchogenic cells remain attached to the developing foregut and that is the reason the bronchogenic cysts appear outside the thorax as these cells form cysts.

The bronchogenic cyst develops as a small solid mass and then as proteinous mucus begins to accumulate and it takes a cystic appearance. The walls of the cysts are thin and cysts have no ducts. As the cyst enlarges it compresses the adjoining structures - trachea, bronchi, and blood vessels in the middle mediastinum. Symptoms vary from being totally asymptomatic to cardiopulmonary compromise.

 Incidence: one in 50,000 hospital admission. Location: 10 % of bronchogenic cysts are located in the middle mediastinum. The mediastinal cysts account for 50 % of all lung cysts and are seen in the paratracheal, carinal, para-esophageal and hilar region. 20 % of bronchogenic cysts are intrapulmonary and develop late and are seen in adults. Other locations are the neck, pericardial, pleural, diaphragm, and retroperitoneal. Size of the cysts: 2 to 10 cm in diameter, usually single.

Cysts are lined with ciliated pseudostratified columnar respiratory epithelium and squamous metaplasia is rarely present. In addition to mucus glands, cartilage, smooth muscle and blood may be present.

 Symptoms in children: Stridor, shortness of breath, dysphagia, superior vena cava syndrome, pneumothorax and pneumonia. In adults: Most cysts are asymptomatic detected in chest x-rays, and recurrent pneumonia.

 Complications: Fistula formation in the tracheobronchial tree, malignancy. Diagnosis: The present generation of sonograms is very sensitive and can detect bronchogenic cysts in utero. In newborns to adults, the chest x-ray and CT scan detect all bronchogenic cysts, rarely MRI is needed.

Treatment: Surgery is the only option in symptomatic cases and in adults lobectomy is usually required for intrapulmonary cysts. Surgery is also recommended for asymptomatic cysts before the start of complications.

Reference: 1.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5320013/

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Spontaneous Pneumothorax.

Spontaneous Pneumothorax

PKGhatak, MD

A slender tall young man around 20 yrs. old suddenly feels sharp chest pain and soon develops shortness of breath. He is told in the ER that he has pneumothorax. His medical and family history does not point to the cause of his illness and the term Spontaneous pneumothorax is used to describe the incidence.

Most frequently, chest wall injuries from an automobile accident and rib fractures, gunshot wounds, and knife attacks, are the common traumatic causes of pneumothorax; pulmonary emphysema, cystic diseases of the lung, and use of ventilators are other main causes of pneumothorax.

Spontaneous pneumothorax results from the rupture of a small subpleural bleb. Usually, 10 to 30 subpleural blebs develop due to inherited diseases or poorly repaired deceased lung tissue. Anyone of these blebs may open up during straining, lifting heavyweight, or without an apparent reason. The outside air pressure is higher than normal pleural cavity pressure.  Any breach in the integrity of lung tissue or airways, the outside air freely enters the pleural cavity. The air around the lung tissues sneezes lung and a lobe of a lung or the entire one side may collapse and that causes shortness of breath. 

Incidence of spontaneous pneumothorax.

The incidence in men is 10 per 100,000 male population per year; in women, the incidence is 4 per 100,000 per year. A tall young person's growth spurts out spaces the growth of lungs, the resultant lung connective tissues are thinly spread out and air sacs can easily form.

Inherited conditions.

Mutation of the FLCN gene accounts for 40 % of spontaneous pneumothorax. FLCN gene codes for a protein Folliculin. Folliculin promotes cell division and cell growth and in addition confers elastic properties. The disease was previously known as Birt-Hogg-Dube syndrome - a constellation of skin tumors, renal cancer, multiple pulmonary cysts and recurrent pneumothorax. The disease is inherited by an autosomal dominant pattern.

Machado- Joseph Disease. It is also inherited by the autosomal dominant mode. This disease manifests as spinocerebellar ataxia and recurrent spontaneous pneumothorax.

Other disease associations are - Marfan syndrome and Homocystinuria.

Management of spontaneous pneumothorax.

Once the diagnosis is confirmed and if the pneumothorax is small (less than 15 % of the chest cavity) the patient is watched in ER for 4 to 6 hrs. Oxygen therapy and pain medication may or may not be required. If the patient is stable and comfortable then the patient is discharged with instructions and subsequent follow up telephone calls.

A larger pneumothorax is evacuated by inserting an intercostal chest tube at the most dependent site. The chest tube usually is self retained and secured at the insertion site by a retention suture. The wound is dressed by a sterile dressing impregnated with medical Vaseline. The distal end of the chest tube is positioned underwater seal and a suction device is used. A Series of air bubbles are seen to come out initially and the lung expands, and healing starts. When the air bubble ceases then a clamp is applied to the chest tube and after several hours later chest x-ray is obtained to confirm the full expansion of the lung and absent pneumothorax. Then the patient is ready for discharge.

Recurrence rate in non-gene spontaneous pneumothorax.                            In about 10 to 30 % of cases, the pneumothorax may recur.

Complications.

Check valve formation and Tension Pneumothorax.                                          This is an emergency situation. The pleural pressure keeps increasing with each breath and the air outlet is blocked by a tissue flap. The other normal lung is displaced laterally and the heart and larger blood vessels are compressed and displaced. Cardiac output falls and severe hypoxemia and hypotension and shock follow. The situation must be corrected by inserting a wide bore needle in the chest cavity and then thoracic surgery is required.

Prolonged healing or no improvement of pneumothorax.                              Repair, resection, or segmental lobectomy may be required to ensure a permanent closure of the damaged lung tissue.

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