The lump maybe a cyst(a bag filled with some solid or liquid material) or a solid tumour(a type of solid growth). A clinical examination by a dermatologist or a general surgeon will be sufficient to make a diagnosis and suggest a treatment for you in most cases. If it is a superficial growth it can be removed by dermatosurgeon, if it has deep extensions it will need a general surgeon or a spine surgeon to operate on it. If it is a rare type of growth or abnormal growth you may need to get a biopsy and a high frequency ultrasound scan done. Warm regards. Dr. Rajdeep Mysore. Chirag Hospital Bangalore.