Welcome and thanks for posting your query to HCM.
I can make out three possibilities after reading your query:
1. Lipoma: It is a collection of fat in the localized area. It may be soft to firm and It do not cause any pain or other symptom.
2. Sebaceous cyst: it is a simple swelling produced by proliferation of oil glands. It do not cause any pain or other symptom.
3. A growing lymph
node: This is proliferation of the lymph gland. It may or may not be painful.
You have not mentioned in your query since how long you have the problem or any associated symptom. So there can be any of the above possibility. You just wait and watch, most of the swelling subsides by its own. Do not try to pinch or squeeze the swelling. If there is not any pain or sudden growth in the swelling then you can wait till your appointment with immunologist.
Your low IgG
and IgA has nothing to do with the swelling so do not worry about it.
With good health wishes
Dr. Sanjay Kumar Kanodia