Respected user , hi Thanks for using Healthcaremagic.com I have evaluated your query thoroughly . * Seems post traumatic hematoma most likely . * Needs clinical assessment or minimum evaluation of high resolution photograph of it for better guidelines . * Present suggestions - keep it clean with antiseptic liquids - ice application 3-4 times a day - keep that hand in arm rest support - in our clinic we recommend penicillin group of antibiotics for better resolution of the lump & prevent infection - analgesic syrup if more pain Hope this clears your query . Welcome for further assistance . Regards .