<prompt> McCallums patch is diagnostic of :Infective endocarditisRheumatic endocarditisMyocardial infarctionTetralogy of fallout TOF  <response>: Answer is B Rheumatic endocarditis Mac Callums Patch is a fiature of mural endocarditis in Rheumatic fever. Mac Callums Patch Mc.Callums patch is the region of endocardial surface in the posterior walldeg of left atrium just above the posterior leaflet of mitral valve. It appears as a map like area of thickened, roughened, and wrinkled pa of endocardium. It is perhaps produced as a result of regurgitant jets. 