I am not sure of your age and the size of tumor
. If u are an elderly person with the lump which has been increasing in size from long time then it is better you visit a Head and Neck surgeon the as soon as u can since you say the lump is hard. If the lump is very small and causing no problem then there isnt anything alarming, yet you need to visit a specialist the earliest to get a diagnosis and treatment.
I hope you found my response to be helpful and informative. If you have any additional concerns I would be happy to address them.