There is no standard method for the diagnosis of vitiligo, which mainly relies on medical history, clinical manifestations and macroscopic observation by natural light and Wood’s lamp, and excludes other hypopigmented diseases. Vitiligo is also clinically distinguished from other congenital and acquired hypopigmented skin diseases.
1, anemia nevus: is a congenital hypopigmentation spot, generally unilateral distribution or confined to a site, round or oval or irregularly shaped light-colored white spots, clear but irregular boundaries, mostly occurring after birth or soon after birth, unchanged throughout life. When rubbing the affected area, the surrounding skin is congested and red, but the white spot does not change color, which is the characteristic performance of the disease, so it can be distinguished from vitiligo.
2, no pigmented nevus: at birth or soon after birth, the damage is often distributed along the ganglion, manifested as a limited or generalized hypopigmented spots, the boundary is blurred, the edge is mostly serrated, almost no pigmentation halo around. White hair is sometimes seen in the white areas, sometimes mixed with light brown corn to lentil-sized freckle-like spots. The lesions on the trunk are mostly square in shape, and those on the extremities are mostly striped or banded. The lesions may expand proportionally with body development, and the morphology and distribution are relatively stable and persist for life. Wood’s lamp performance for non-fluorescent white incomplete depigmentation, different from the vitiligo porcelain white lesions.
3, simple furfuraceous rash: mainly seen in children aged 3~16 years old, lesions occurring on the face, especially bilateral cheeks, also seen on the neck, upper limbs, trunk and lower limbs. Often multiple, diameter 1~4cm or larger, can naturally fade.
4, lichen planus: This disease is most often seen in young adults, with high temperatures, excessive sweating, and immunosuppression as the most common triggers. The lesion is characterized by a circular or oval-shaped, variable-sized rash with clear boundaries, which can be pale white, pale red, yellowish brown, or a variety of colors coexisting in a florid pattern and covered with a thin layer of bran-like scales. It often occurs in areas rich in sebaceous glands, usually on the forehead, back and other areas. Under Wood’s lamp, it shows yellowish or light brown fluorescence.
5.Idiopathic droplet hypopigmentation: manifested as multiple well-defined round or polygonal white spots or porcelain white, 2~8mm in diameter, commonly found on the forearm and the extensor side of the calf, increasing in number with age, mostly after 30 years of age, with peak incidence after 70 years of age, the white spots themselves rarely change and do not regenerate pigment and disappear naturally. The number ranges from single to hundreds.
6, post-inflammatory hypopigmentation: patients have a history of primary disease, such as psoriasis, eczema, contact dermatitis, trauma, etc. Hypopigmentation is limited to the site of the primary disease lesion, which is generally temporary and can fade on its own.
Hypopigmentation caused by local injection of glucocorticoids: Hypopigmented spots appear at the site of glucocorticoid injection, often in the shape of lines or bands, or irregularly. Hypopigmentation may occur after a single local injection or after multiple injections, and the hypopigmentation may fade on its own or persist.
8.Solar leukoplakia: It mostly occurs in summer, and it is usually found in sun-exposed areas such as the face and neck, forehead, back and upper extremities. Most patients have obvious history of sun exposure before the onset of the disease, and some patients have no obvious history of sun exposure. The initial lesions are mostly erythematous and later appear as hyperpigmentation with desquamation and gradually appear as hypopigmented patches or patches. The lesions can be bean-sized hypopigmented spots with smooth surface and no scaling, and the borders are mostly indistinct, or they can be irregular flaky hypopigmented spots.