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1.The history suggest an infective aetiology - either an
abscess, hair follicular infection or bony pathology.
2.If you are my patient i would have examined and ask for a
ultrasound examination and a x-ray involving joint and bone AP/LAT.
3.Ultrasound - gives me the nature of the lump, its source and extension.
4.X-ray will give me the characterisation of the lesion if its bony source.
5.Further if abscess or infective collection -
incision and drainage followed by a course of antibiotic will be given.
6.In case of bony after characterisation depending on findings treatment involves. Good luck.
Hope i have answered your query.
Any thing to ask do not hesitate. Thank you.