Cricketer Yuvraj Singh has a "non-malignant tumour" in his left lung. This is the reason why the flamboyant left-hander opted out of the upcoming ODI cricket series against West Indies.Yuvraj's mother Shabnam said this in a statement. She said that detailed scanning and biopsy reports indicated that the tumour is non-malignant and non-threatening and can be treated through proper medication and therapy.