Hard lump on bone in armpit. it doesn't hurt but it's been there for 4-6 months could i have cancer?

Calcified Nodule: Your armpit is usually mostly fat and pilosebaceous glands and maybe some lymph nodes. What you may have is not a bone but most likely a calcified cyst or calcified lymph node. If you have a family history of cancer, see your doctor for definitive diagnostic biopsy..

See below: There are different causes of lumps/ masses in the armpit, a simple physical exam by your doctor can differentiate a benign ( non cancerous ) mass or a mass that needs furthrr investigation, like ultrasound. Biopsy is usually the definitive test to diagnose cancer for mass.