Hi,
Welcome to HCM,
You are having lighter patches on chest and abdomen.
Lighter means hypopigmented.
They are increasing and after hot bath there become redness around the patches.
After such history I feel you may be having either
tinea versicolor or
pityriasis alba..
Both the conditions are mild and benign.
Tinea versicolor is superficial
fungal infection caused by Mellasezia furfur..
Pityriasis alba is superficial eczema... And caused by sunrays,dust,worms or infection..etc
Antifungal tablets and cream may be helpful in tinea versicolor.
And pityriasis alba may respond to mild
steroid or tacrolimus and remove the suspected cause.
You
contact dermatologist for firm diagnosis and treatment ..
I hope you got my answer.
Thanks ..
Dr. Ilyas Patel MD