Unilateral pulmonary agenesis: an uncommon cause of lower zone lung opacity.

Congenital abnormalities of the lung are rare and are often misdiagnosed. We report the case of a young girl who was initially diagnosed to have pleural effusion with collapse. After detailed evaluation including computerised tomographic (CT) scan and fiberoptic bronchoscopy, a final diagnosis of unilateral pulmonary agenesis was made. This condition must be suspected in differential diagnosis in a young person presenting with features of lung collapse.