What is the name of the acquired disorder characterized by complete loss of pigment of the involved skin?

Vitiligo is the correct answer as it is an acquired disorder that leads to the complete loss of pigment in the skin affected by the condition. This occurs due to the autoimmune destruction of melanocytes, which are the cells responsible for producing melanin, the pigment that gives skin its color. As a result, areas of skin become lighter or can appear completely devoid of pigment, leading to the characteristic patches associated with vitiligo.

In contrast, tuberous sclerosis is a genetic disorder that can lead to skin lesions, but it is not characterized by loss of pigmentation. Pityriasis alba appears as lighter patches of skin but is often considered a mild form of eczema and is not associated with complete pigment loss. Tinea versicolor is a fungal infection that causes discoloration of the skin but generally results in lighter or darker patches rather than total pigment loss, making vitiligo the most accurate answer for this question.