Can a hard immovable lump under the skin latched into the flesh be cancerous if it has remained unchanged in size or shape for 4 years?

Unlikely: Observe the mass about once a month, if it doubles in size, ulcerates, bleeds or becomes painful see a doctor. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex.