My Dear Welcome to healthcaremagic As you might be aware syphilis is a sexually transmitted disease. The black patches that you described are seen on palms and soles of a syphilitic patient in its secondary stage which starts several months after the first stage following sexual relations with an infected partner. In the absence of any such history in your case, i am inclined to set that possibility aside. however, in case of a doubt, a simple blood test like TPHA or FTA-ABS will confirm the doubt. These patches could be due to fungal infection which can be confirmed by scrapings test or due to a drug eruption caused by certain drugs including sulpha medicines, anticonvulsants, or antibiotcs or painkillers about which you have not given any hint. In any case, please observe them and seek opinion from your doctor who will examine your health and prescribe suitable medication. i hope you will follow the advice and get well soon.