small lumps 1.5 cms, 3mm,2mm, brain cancer or bain tumor?.

Hello and welcome to e health forum.

Presence of such a lump on the head, could be a benign cyst like a sebaceous cyst.

But to confirm the cause of the lump, a physical examination is very necessary.

Brain tumors and cancers , do not present in the form of such lumps in the head scalp. They more likely present with headache, neurological deficit, seizures, dizziness, etc.

You might consult with your doctor for a examination and proper advice.