<sod >A boy of 15 was stabbed to death when a mass brawl broke out as around 200 teenagers were leaving a 16th birthday party at a community centre.< eod>< sod > A 15-year-old drill rap fan stabbed to death when a mass brawl broke out as around 200 teenagers were leaving a 16th birthday party has been pictured for the first time.< eod>