red skin near folds of joints

[Ka1129]

I recently lost 40 lbs, since that time I have red skin at and near my joint folds; arms inner elbow; under arms; and front of thighs not in joint, but running down a solid 4 inches and across the thigh.  It almost looks like a birthmark, there are no bumps, its not itchy and it doesn't hurt, it just looks horrible in shorts or bathing suit.  I have sensitive skin, and would periodically get marks on skin if I leaned on something or crossed my legs, but this is not going away no matter what I do.  And it is as red as can be, could almost be mistaken for a good sunburn but ends about mid thigh?  If I push my finger down on it, it temporarily turns white, but goes red right away..Any idea's.  I am taking topril, but was prior to the weight loss.  

[Bhupinder Kaur, MD]

Hello,
Without examination,confirmation of a diagnosis is tough but it can be intertrigo or erythrasma. Erythrasma is a chronic superficial infection of the intertriginous areas of the skin.It is true that groins are effected but the typical appearance is well-demarcated, brown-red macular patches. The skin has a wrinkled appearance with fine scales.

It has to be differentiated from contact dermatitis,psoriasis,sweat dermatitis and fungal infections which may mimic it.Wood lamp examination and gram staining are the tests for its diagnosis.

So nothing can be confirmed without examination.The standard therapy of erythrasma is antibiotics and antifungals because it is caused by a bacteria C minutissimum.Erythromycin is the drug of choice.
I hope that helps.Take care and pls do keep me posted on how you are doing or if you have any additional queries.Kind regards.