Large, squishy, painless lump on head (10cm wide). what does this sound like?

How long do you have: Benign conditions like sebacious cyst -arising from bloked seb. Duct opening , lipomas -lipd tumor, a condition called dermoid cyst (if is nearly of long drn in terms of years present in which case need to r/o erosion into underlying skull bone), fibromas -another benign tumour made of tissue like scar iif noticed of short drn, seek help by seeing a doctor as secondary tumour for cancer can sit.