A 10 year old male presented with fever, sore throat followed by pain and swelling in knee joint and skin rash. On chest examination there was was pericardial rub and on blood examination, high titre of a specific serological test was detected. a. What may be the provisional diagnosis? b. How will you proceed for confirmation of diagnosis? c. Write down the histomorphological features of organ involved. d. What may be the complications in this case?