See your PCP. There are many different causes. Some are concerning and need immediate attention, others will resolve on their own. Most of the time if it is not associated with an obvious cause (like infection), ultrasound is used to image the area and differentiate between solid and cystic etiology. The lump should be examined by a pcp and he or she will determine the work up necessary.
See below. This could be anything from a swollen lymph node from a viral infection to a cancer. Seek medical attention.
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