Relationship Between Vitiligo and Psoriasis May Be Due, In Part, to Immunity

Vitiligo and psoriasis may share such a close association with one another due to immunity, according to a study published in Skin Research and Technology.¹

However, Mandelian randomization studies have pointed to a lack of a causal relationship between the 2 conditions, according to researchers.

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Background and Methods

Several studies have confirmed some sort of relationship between psoriasis and vitiligo, including a 2019 study published in the American Journal of Clinical Dermatology,² where researchers reported an association via meta analysis.

The study involved a 32-year-old male with both psoriasis and vitiligo, both of which were confirmed through skin biopsies and various diagnostic tests, including blood and urine analyses, dermoscopy, and skin imaging.

In the Mendelian randomization study, researchers utilized psoriasis data from the IEU Open GWAS Project and vitiligo data from NIH databases.

Findings

The patient assessed in the case report presented with multiple erythematous and scaly lesions along with bright red depigmented spots with blurred edges prior to treatment. After a month of conventional therapy, the intensity of erythema reduced, and scales disappeared, leaving some psoriasis lesions with less vivid red spots and clearer edges.

Two months into treatment, the erythema and scales had cleared from most of the body, except for the extremities. The remaining spots turned white with distinct edges, and pigment islands were visible.

Clinical tests, including blood counts, urine analyses, and biochemical and immunological exams, showed no significant abnormalities before and after treatment. Dermoscopy revealed punctate blood vessels and scales in psoriasis lesions, while vitiligo lesions displayed residual pigment and reticular hypopigmentation. In areas affected by both conditions, features of both psoriasis and vitiligo were evident.

Skin CT scans showed hyperkeratosis and capillary dilation in psoriasis lesions, a decrease in basal layer pigment in vitiligo lesions, and a combination of these features in areas with both conditions. Histopathology confirmed hyperkeratosis, Munro microabscesses, and neutrophil infiltration in psoriasis, while vitiligo lesions showed reduced melanocytes and melanin. Areas with both conditions exhibited features of both diseases.

Researchers conducted a Mendelian randomization analysis to assess the causal relationship between vitiligo and psoriasis. The analysis found no significant causal relationship between vitiligo and psoriasis, with p-values indicating no causation in either direction.

Conclusions

"The results of this study suggest that the association between vitiligo and psoriasis as an autoimmune disease is strongly immunologically related, but neither Mendelian randomization study supports causality between the two diseases in both directions," according to Li et al. "Our findings highlight the importance of considering the association between these two conditions as correlational rather than causal."

Potential limitations of the study include its limited patient sample size and the potential of the Mendelian randomization not to be generalizable.

Researchers suggested that while this research has no present, immediate implications, further research exploring the relationship between vitiligo and psoriatic disease may be valuable.

References

1. Li J, Shen Q, Wang Y, Guo C, Ma Y, Zhang Y. The relationship between psoriasis and vitiligo: from a comprehensive study. Skin Res Technol. July 19, 2024. https://doi.org/10.1111/srt.13868
2. Yen H, Chi CC. Association between psoriasis and vitiligo: a systematic review and meta-analysis. Am J Clin Dermatol. 2019; 20(1): 31-40. doi:10.1007/s40257-018-0394-1