Causes: Acromegaly, allergic reaction to food or medicine, leukemia, lymphangioma, neurofibromatosis, pellagra, pernicious anemia, amyloidosis, angioedema, beckwith syndrome, tongue cancer, congenital micrognathia, down syndrome, hypothyroidism, infection, strep infection, pituitary gland tumor, etc. are some of the causes of enlarged tongue.