Hello. Thank you for writing to us at healthcaremagic The rash that you notice at the dressing site is most likely due to allergic contact dermatitis either to the topical antiseptic/ antibacterial that may have been part of the dressing Or it could be due to allergy to adhesive used to hold the dressing at the site. If I was the treating doctor I would suggest you to use a moderately potent topical steroid e.g fluticasone propionate 0.05% cream, twice daily, at the site of rash. Steroids are antiinflammatory, immunosuppressive in action and would take care of the allergic rash. Regarding the knot, it is most likely due to thrombophlebitis of the vein thorough which the picc line was accessed. The knot would resolve on its own in a few days. An Oral antiinflammatory e.g ibuprofen would help decrease the pain, swelling. Topically you may use a heparin sodium gel, which would act as an antithrombotic. Regards