<s>[INST] I have a 1/2 grapefruit sized mass on my inner thigh (almost groin area). There appears to be a fibrous portion which extends to just above my knee and the pain (which is excruciating) radiates to the inside of my ankle. This appeared in a matter of hours and has lasted 3 days. [/INST] Hello, This is a very rapidly growing swelling which is extremely painful.it could be a hemorrhagic phenomenon or an infective process. Anyway, it must be investigated. If possible biopsy should be done & thereafter treated accordingly. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Nirmal Chander Gupta, Orthopaedic Surgeon </s>