Why do I have a large patch on my neck that keeps spreading and changes color like dirt?

Hello,

Welcome to icliniq.com.

I understand your concern. This condition is known as pityriasis versicolor. It is a form of superficial fungal skin infection. The color of lesions can be dark or hyperpigmented, light or hypopigmented, red or erythematous. There are different colors like light brown or dark brown hence named pityriasis versicolor. These are usually asymptomatic and on rubbing the surface with a finger, one can see fine, white powdery scales. I suggest you the following treatment. Take Capsule Itraconazole 200 mg once a day for five days. Apply Nizoral (Ketoconazole) 2 % shampoo at the time of bath on lesions, you can leave for five minutes and then wash it off. Do it daily for one week and then twice per week for the next six weeks. The lesions usually take six to eight weeks to subside completely. Do take care of yourself. Hope this was helpful. Kindly revert for further queries. Regards.