Hi XXXXXXX

Thanks for posting your query.

The most common reason for this type of patch in this area is a fungal infection ( also known as a tinea infection). This usually causes white to pinkish patches with definite margin which may or may not itch.
These infections are common is this area as this area is hairy, warm and has a good amount of moisture due to perspiration. This is the most favourable ground for a fungus to grow.
This is normally treated by a local anti-fungal cream like a clotrimazole ointment. At times oral drugs are also needed.
Dexamethasone is a steroid which can only help in allergic skin conditions where it only helps relieve itching.
Please visit your primary care physician and get yourself examined first. A proper evaluation can help us start the right treatment.
I would also suggest the following:
•     Please avoid tight fitting clothes
•     Maintain good local hygiene.
•     Please do not apply anything without seeing your doctor first.

I hope this answers your query. I will be glad to reply any follow up queries that you have.

Please accept the answer in case you do not have any further queries.

Regards,
Dr.Pragnesh

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