Case 12:
A young child presents with an opaque hemithorax on a routinely performed X-ray chest. CT scan is requested for. What is the diagnosis?
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Imaging Findings
Study shows aplastic right lung with cardio-thoracic shift to the same side, and compensatory left lung hyper-inflation.

Agenesis of lung is a rare anomaly. Bilateral agenesis has been described in eight cases and is associated with multiple malformations that are incompatible with life.

This condition has been classified into three groups by Boyden (1955)
Group 1 complete absence of one or both lungs (agenesis)
Group 2 suppression of all but a rudimentary bronchus (aplasia)
Group 3 abortive growth (Hypoplasia).
Initially these patients are often misdiagnosed and treated as recurrent pneumonia or collapse with consolidation. A high index of suspicion is required during clinical examination so as to ask for appropriate radiological investigations

Associated Anomalies
Associated anomalies are present in more than 50% patients. Multiple congenital anomalies reported are cardiac defects such as ASD, VSD, PFO (patent foramen ovale), A-V canal, TOF, PDA, single ventricle etc.
In skeletal abnormalities the commonest is hemivertebrae and absent ribs, causing scoliosis.
The gastro-intestinal abnormalities include atresia, malrotation, tracheo-oesophageal fistula, absent spleen and anomalies of diaphragm either on ipsilateral or contralateral side.
The genitourinary anomalies include renal agenesis, cystic kidneys and agenesis of ovary or testis.  Rarely brain and eye malformations are also known.  Ipsilateral facial abnormalities have been also reported.

In all such cases when patient does not improve after being diagnosed with recurrent pneumonia, a differential diagnosis of pulmonary agenesis should be considered especially if patient fails to improve with the routine therapy.

Dr. Ashok Raghavan, Manipal Hospital, Bangalore