Final answer:
White patches on the skin that do not tan and are caused by an autoimmune reaction are usually indicative of vitiligo. Vitiligo causes depigmentation and may be treated with medications or phototherapy, but results can vary and a dermatologist should be consulted.
Step-by-step explanation:
The white patches that do not tan and are caused by an autoimmune reaction are typically a sign of a skin condition called vitiligo. Vitiligo leads to depigmentation, where portions of the skin lose their pigment cells, or melanocytes, resulting in lighter colored patches of skin. This condition is especially noticeable on darker skin.
Treatment for vitiligo often involves the goal of restoring color balance and can include options like topical corticosteroid creams, immunosuppressants, or phototherapy. These treatments may help restore some pigmentation to the white patches. However, the results vary from person to person and some may not see significant improvement. It is crucial to consult a dermatologist to discuss the most appropriate treatment options based on individual cases.