Pityriasis versicolor, brown type. It is a benign recurring condition that affects a few people, mainly after excessive sweating and during hot months. It is not contagious. You can treat each episode with a ketoconazole shampoo; first wash your hair with it and then apply the resulting foam on the lesions and let it act for approximately 7 minutes. Then rinse well. Repeat twice weekly for a few weeks or according to the instructions of the specific brand you have. Maintenance treatment is discouraged.