A 71/2 months old child with cough, mild stridor was staed on oral antibiotics. The child showed initial improvement but later developed wheeze, productive cough, and mild fever. X-ray shows hyperlucency and PFT shows an obstructive curve. The most probable diagnosis is:

The patient in question is presenting with charachteristic features of bronchiolitis obliterans. Fever, cough, and wheeze are common clinical features of bronchiolitis obliterans and a period of initial improvement may well be seen in cases of bronchiolitis obliterans (Initial sign of B.O). Hyperluscency or chest X-Ray and obstructive curve on pulmonary function tests fuhur suggest the diagnosis of bronchiolitis obliterans. Ref: Nelson 18th Edition, Page 1782