Unilateral lung hypoplasia: a rare cause of unilateral opaque hemithorax in chest X-ray in a young boy.

Congenital abnormalities of lung are very rare entity, and very often under or misdiagnosed by physicians. The present case, a 12-year boy, who was initially diagnosed as unilateral massive pleural effusion with collapse of lung, and after thorough investigation, including CT scan of thorax, fiber-optic bronchoscopy, and echocardiography, a final diagnosis of unilateral lung hypoplasia was made. So if a teenager present with a unilateral opaque hemithorax in chest X-ray, this entity may be a differential diagnosis.