Conversation: The conversation between human and AI assistant.
[|Human|] I noticed a large lump on my sons lower right costochondral junction yesterday.  It seems to have appeared all of the sudden.  There is no pain or any other symptom present.  I am scared it could be some kind of tumor.  He fell almost a week ago and hit his chest on a picnic table, but I dont know if it is related.
[|AI|]  Hi. Thanks for your query. With the history of trauma a week ago and painless, symptom-less swelling in the Costco Chat Doctor.  IT has appeared sudden, it is possible a small blood vessel ruptured in an already traumatized area. If the hematoma is not tight, it is painless. I do not think there is anything to worry as about. This can be confirmed by ultrasonography and / or aspiration. If confirmed to be hematoma, it can be left alone, or just add an anti-inflammatory medicine for a few days.