<prompt> A Bone marrow transplant receipient patient, developed chest infection. ON chest Xray Tree in Bud appearance is present. The cause of this is:KlebsiellaPneumocystisTBRSV  <response>: 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_s1031Tree 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. 