Hi.. doesn't look like a matter of concern. However a check up from oral medicine specialist and if needed a biopsy is required. Regards

I would suggest you to wait observe its growth. Is it painful? Is this increasing in size? Is there any diseased tooth nearby? Please get a biopsy done if this is the case.

Hi....first we need to know the duration of the lump and observe any change in size , shape n colour of the lump....maybe we need to perform biopsy...regards

Hello..we need to know duration ,cause etc from which it developed..so kindly visit dentist as soon as possible for clinical examination and treatment.

The first question would be the duration of the lump, whether it has been observed in the last few days or is present since a long time...... based on the description and picture that you have provided, this could be a traumatic lesion which might heal with time...... but most likely it is melanotic naevus, which will never heal on its own and does not require any treatment as such if it does not show any changes of colour, shape, size or contour..... If any changes are observed immediate excision of the lesion is highly recommended..... Regards.....

Do you suffer from cheek biting regularly?  Please visit a dentist for proper diagnosis. It looks like a hemetoma  ( blood filled boil)due to injury. Removal of wisdome teeth will solve the problem if you have those.

Based on the picture you have sent, it could be      a Macule or Nevus - excessive melanin  pigmentation.. like a 'Mole' as commonly said and seen  if it is on skin. Inside oral cavity, it isn't common.  Or it can be Amalgam Tattoo, if she has any Silver fillings adjacent to it. Not of immediate concern but at the same time dont neglect, it may not go automatically. Go to a dentist, he may remove it with LASER or biopsy if he feels necessary.