Pea size movable lump 1/2 in. Front of ear at jaw hinge 20+ yrs. No pain, symptoms, etc. Had numerous f/b pet/cts but never mentioned. Have TMJ cause?
Not likely. Movable lump not likely TMJ origin. My guess with 20 yrs presence is a benigh paratid tumor.
Location. What you think is 1/2 inch in front of jaw joint may actually be part of the joint. Please ask your dentist to evaluate. If not anatomically part of TMJ the next step is to have physician take a look.
Lymph node. It's not unusual to have a reactive lymph node become evident in the area where you have the nodule appear. If it has not been increasing in size or causing increased amount of discomfort. You would be okay to have your health practitioner or dental provider monitor. Most likely not TMJ related though.
Soft tissue mass. Pea shaped in that region and freely mobile is most consistent with a small inculsion cyst. Similar to the larger ones that people can get on there back and neck. Sort of like a very large whitehead. Rarely thaty can get infected and cause an abscess that needs to be drained.