hi, I obsorved a lump on my back at the age of 17, Its never painful, 5 years back i have suffering from back pain some one press the lump and a black paste came from the lump, since then its leacking after time to time in very less quantity (white paste or liquid hole comes from), i went to 3-4 doctors they said this is a cyst , it soften and harden time to time and painful, can any one tell me, it can effect my lungs or can led to cancr?