What causes itchy mark on chest and stomach?

Brief Answer:
Pityriasis XXXXXXX or Tinea versicolor

Detailed Answer:
Hello,

Thanks for the query and the picture.
As the image appears it is described as hypopigmented macules on the upper trunk. THey are not clearly margins. You had not mentioned if they are itchy and/or if you are able to see powder or scales coming out of the patches.

Though my highest on the list of possibilities
Pityriasis XXXXXXX - very common and non worrisome. Easily treatable with simple effective moisturizers available over the counter like Nivea cream. The patches go away in a week's time of use.
Tinea versicolor - a type of fungal growth on the skin typically in hot and humid climate. You will find some uneasiness if not itching over the lesions. They are non worrisome, easily treatable with antifungal agents for two weeks.

You can try the former first and if not helping then I suggest you to take these information to a Dermatologist who can examine the lesions before confirming a diagnosis and treating it.

Hope this is helpful.

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Brief Answer:
Fungal infection

Detailed Answer:
You had already used a moisturizer then, it seems itchy so I think the later possibility is higher, ie tinea versicolor.
You need both oral antifungal and a topical antifungal like selenium sulfide.
Please see a local doctor for its prescription. They have to be used at least for two weeks can be extended till 4 weeks for complete resolution.

Hope this is better.

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