hello friend, This brownish discoloration which you have got in the groin region can be because of many reasons. It can be acanthosis nigricans which is characterised by black discoloration of skin, usually thickened and commonly found in obese people. Or it can be post inflammatory hyperpigmentation that is discoloration left after some previously present disease like fungal infection or persistent friction. But all these can conditions can be well treated if appropriately diagnosed. But, in skin conditions, it is the direct visualization which is required so as to make a correct diagnosis . Because before starting treatment, diagnosis should be confirmed. So, better you visit some dermatologist and you can later consult to me, so as to take advice , if you wish, once it is diagnosed correctly. Or you can start the treatment as your dermatologist will suggest. Thanx. Get well soon. Stay healthy.