<prompt> Mac Callums patch is diagnostic of -Infective endocarditisRheumatic endocarditisMyocardial infarctionTetralogy of Fallot ToF  <response>: Ans. is b i.e., Rheumatic endocarditis Pathological features of Rheumatic carditis Acute Rheumatic carditis o There is diffuse inflammation and aschoff bodies in any of the three layers of heart - Pancarditis - a Pericardium - Fibrinous or serofibrinous pericarditis also know as bread butter pericarditis. Pericarditis generally resolve w ithout sequelae. b Myocardium - Diffuse non-specific myocarditis with Aschoff bodies. c Endocardium - Small warty projections, i.e. verucae along the line of closure on the valvular leaflets especially on left side mitral valve. Chronic rheumatic carditis o Chronic RHD is chracterized by organization of the acute inflammation and subsequent fibrosis, o In particular, the valvular leaflets becomes involved and characterized by - Leaflet thickening Commissural fusion Shortening, thickning and fusion of chordae tendinae. o Fibrous bridging across the valvular commissures and calcification create fish mouth or Buttonhole stenosis. o Mitral valve is involved most commonly, o RHD is the most common cause of mitral stenosis. o Aortic valve is second commonest valve to involve, o Tricuspid valve may also be involved. o Irrigular thickening of the posterior wall of left atrium - MacCallum plaque, o MacCallum plaque is due to subendothelial collection of Aschoff nodules. 