A Bone marrow transplant receipient patient, developed chest infection. ON chest Xray Tree in Bud appearance is present. The cause of this is:

D i.e. (RSV) - Most common cause of tree in bud (bronchiectasis) appearance is Mycobacterium tuberculosis (endobronchial). Most common specific cause of tree in bud appearance in HSL (bone marrow) transplant patients is CMV (30-70%) > RSV (18%) > M. tuberculosis (5-6%) > Pneumocystis > Invasive aspergillosis. Tree in Bud appearance 6 Months) - Pneumocystis - S.pneumoniae - CMV, Seasonal respiratory virus (RSV & para influenza viruses) - Pneumocystis - Toxoplasma " v:shapes="_x0000_s1031">Tree in bud appearance (or gloved finger appearance) is depiction of normally invisible branching course of intralobular bronchiole on HRCT. It indicates the endobronchial spread of disease lit bronchiolar luminal impaction with mucus, pus or fluid, bronchiolar wall thickening, peribronchiolar inflammation and dilatation of distal bronchioles. On HRCT, it appears as peripheral (within 5mm of pleural surface) small (2-4mm) centrilobular well defined nodules connected to linear branching opacities with more than one contiguous branching sites.