Diaphragmatic agenesis or complete absence of a hemidiaphragm in adulthood is rare     . It is reported to be about 6% of all Congenital Diaphragmatic Hernia (CDH)  . Congenital diaphragmatic hernia (CDH) is a congenital malformation of diaphragm, where gastro-intestinal loops and other abdominal viscera herniate into the thoracic cavity through a defect in the diaphragm. In extreme form of diaphragmatic maldevelopment, there may be a complete agenesis of diaphragm. It may remain asymptomatic for decades   . Diaphragmatic agenesis is usually associated with herniation of gastro-intestinal loops and other abdominal viscera into the thoracic cavity    . Patient may come with respiratory and/or gastrointestinal symptoms and even strangulation of gut. We present a case of agenesis of left hemidiaphragm in a 62-year-old male who came with recurrent respiratory infection but without diaphragmatic hernia. He was found to have complete absence of a left hemidiaphragm and a large cyst arising from the lower lobe of left lung occupying common thoraco- abdominal space thus created.
2. Case Report
A 62-yr-old man, presented to our hospital with the history of recurrent respiratory tract infection, upper abdominal pain and upper abdominal discomfort. He also complained of episodes of nausea and postprandial fullness. He was referred to our department with the diagnosis of diaphragmatic hernia.
On admission, he was stable in room air. Physical examination showed absent breath sounds and dull to percussion findings at the left lower chest. The chest radiography revealed a well-defined air filled structure in relation to lower part of left lung.
However, Barium meal stomach shows stomach in its intraabdominal position. Computed Tomography scan showed a large cyst in the left lower hemithorax in relation to the lower lobe of left lung which showed extension into the upper abdomen (Figure 1 and Figure 2).
The patient underwent surgical exploration. During surgery, he was found to have complete absence of a left hemidiaphragm and a large cyst arising from the lower lobe of left lung occupies the common thoracoabdominal space displacing the abdominal viscera downwards which were lying fixed to the abdominal wall in a thick fibrous membrane (Figure 3).
3. Surgical Procedure
Left posterolateral thoracotomy was done under general anesthesia to open left hemithorax. Multiple dense adhesions were found and left lung was freed from chest wall and pericardium after adhesionolysis. After careful dissection, a large cystic structure was found in relation to the lower lobe of left lung. Diaphragm was found absent on the left side and the cyst was found extending down into the abdomen occupying the common thoracoabdominal space. The cyst was decompressed and completely dissected out from thoracoabdominal wall. Cyst wall was opened, excised, bronchocystic
Figure 1. CT scan showing cyst occupying left hemithorax.
Figure 2. CT scan showing extension of the cyst lying inside upper abdomen.
Figure 3. Cyst freed all around, fluid asprated, congenital absence of diaphragm.
communications identified and closed. Cyst content was thick with necrotic debris. Adjacent Abdominal viscera were found displaced downwards in the abdominal cavity and fixed in a thick overlying fibrous membrane. There was no herniation of abdominal organs into the thoracic cavity. Diaphragmatic agenesis did not require any additional procedure. The left lung could be fully expanded and chest was closed after putting a chest drain.
Postoperative recovery was uneventful. Patient was well in the follow-up.
Developmentally diaphragm originates from septum transversum, pleuroperitoneal membrane and the thoracic wall    . The gastrohepatic ligament and dorsal mesentery also contribute to its development. Agenesis of the hemidiaphragm involves non-development of all of these components. Congenital Hemi-Diaphragmatic Agenesis (CHDA) may be differentiated into partial and complete agenesis depending on the presence of diaphragmatic remnants  . Complete agenesis of diaphragm, usually involves one side, but, sometimes both sides. In case of complete diaphragmatic agenesis no diaphragmatic remnant is present whether in partial diaphragmatic agenesis; diaphragmatic remnants may be present especially on posterior aspects.
Cunniff et al. reported a 6% incidence of diaphragmatic agenesis in their review of 102 live born children with congenital diaphragmatic defects  . A failure of pleuroperitoneal membrane to close the pleuroperitoneal canal on the involved side was considered to be the probable etiology by some authors but others proposed a failure of all the precursors components of diaphragm to develop    . Environmental factors and various medications have been proposed to play a key role in development of the CDH in animal models.
Chest radiograph cannot specifically diagnose the CHDA but is a modality of choice in case of CDH. Barium studies, CT scan and MRI are important diagnostic modalities for the diagnosis of the diaphragmatic abnormalities. CT scan and MRI are important diagnostic modalities for the delineation of the diaphragm and its abnormalities.
In case of symptomatic presentation, an early surgical intervention may be beneficial for the patient. The surgical repair of the lesion is very difficult owing to completely absent diaphragmatic tissue or if present not sufficient enough to accomplish the repair. Various authors used different treatment options including, prosthetic materials, abdominal wall and chest wall muscle flaps, suturing the chest margins with liver, use of pre-renal fascia and some advocated no repair at all   . However, many cases with CDH, treated with mesh incorporation in the defect, showed prosthesis related complications and even recurrence of the herniation  .
In our case, presentation of diaphragmatic agenesis was late in the adulthood with respiratory and abdominal symptoms. Chest x-ray revealed a structure with air-fluid level in the left hemithorax but Barium studies did not suggest diaphragmatic pathology. Computed Tomography scan showed a large cyst in relation to the lower lobe of left lung. On surgical exploration, he was found to have complete absence of a left hemidiaphragm and a large cyst arising from the lower lobe of left lung occupied the common thoracoabdominal space displacing the abdominal viscera downwards which were covered with thick fibrous membrane.
The absence of diaphragm had possibly allowed the lung cyst to enter into the abdomen and the cyst was a protective barrier for development of diaphragmatic hernia into the bony hemithorax. The patient had grown into adulthood without symptoms and survived to adulthood. The presence of pleuro-peritoneal adhesions may have played a role in preventing herniation. The presence of cyst into the abdomen had possibly initiated a chronic inflammatory process which resulted in the formation of a thick fibrous membrane over the displaced abdominal viscera and fixed the abdominal contents in a new position which helped the abdominal viscera to contain in the abdomen even after the excision of the cyst. Therefore, reconstruction of a new diaphragm to separate the thoracic and abdominal contents was not necessary. The expanded lung with compensatory hypertrophy was found to have taken care of the potential space below the lung.
 Sung, H.Y., Cho, S.H., Sim, S.B., Kim, J.I., Cheung, D.Y., Park, S.H., et al. (2009) Congenital Hemidiaphragmatic Agenesis Presenting as Reversible Mesenterioaxial Gastric Volvulus and Diaphragmatic Hernia: A Case Report. Journal of Korean Medical Science, 24, 517-519.
 Cunniff, C., Jones, K.L. and Jones, M.C. (1990) Patterns of Malformation in Children with Congenital Diaphragmatic Defects. Journal of Pediatrics, 116, 258-261.