<s>[INST] I can feel a small lump on the underside of my arm, maybe 5 inches or so down from the center of my right armpit. About the size of a pea. I can pinch the skin over the lump without moving the lump. No other lumps that I can detect in the armpits, neck or chest. No known health issues...sweats, fever, etc. I am 68. Thank you. [/INST] Hello dear , hiWarm welcome to Healthcaremagic.comI have evaluated your query thoroughly .*  This seems in relation with probable sebaceous cyst or lymph node most    likely .*  Should get examined by your doctor or if visible above the surface can    share a photo pic for confirmation in details .Hope this will help you for sure .Regards dear take care . </s>