Vogt–Koyanagi–Harada disease (VKH) is an autoimmune disorder affecting melanocytes. We report a case of VKH with psoriasis.
A 67-year-old Japanese man developed erythematous plaques on the scalp and elbows 5 years prior. He had exhibited vitiligo on the face, trunk and both hands for 10 years. He also noticed blurred vision preceding the vitiligo, and was diagnosed with bilateral uveitis 4 years prior, but had no history of ocular trauma or ocular surgery. When he visited our hospital, areas of symmetrical depigmentation were observed on the scalp, bilateral upper eyelids, neck, bilateral extremities and trunk (Fig. 1). Poliosis and alopecia were noted, but the poliosis was partial and it could not be determined if the alopecia was androgenetic. Erythematous plaques with scales were also observed, completely confined to the vitiligo in the posterior cervical region and bilateral elbows (Fig. 1). Blood tests for syphilis and angiotensin-converting enzyme were negative. The chest X-ray showed no abnormalities. An ophthalmological examination revealed a decrease in visual acuity (right, 0.3; left, 0.4) and bilateral uveitis. A fundoscopy revealed “sunset glow” fundus, characteristic of VKH (Fig. 2). Syphilis, sarcoidosis and Behçet's disease were ruled out. A biopsy specimen of the vitiligo of the elbow demonstrated absence of melanin and the presence of clear cells in the basal layer. S-100 and Melan-A staining revealed no positive cells. A biopsy specimen of the erythematous plaque on the elbow demonstrated parakeratotic acanthosis with the elongation of the rete ridge, compatible with psoriasis. He was diagnosed with incomplete VKH (i.e. lacking neurological involvement) and psoriasis vulgaris. Topical steroids were effective for the psoriasis. However, treatment with oral prednisolone failed to improve the patient's vision.
The ophthalmological features of VKH are bilateral choroiditis, ocular depigmentation and chronic anterior uveitis in the absence of ocular trauma or surgery. Neurological, auditory or cutaneous findings, including vitiligo with symmetrical distribution, are also listed as diagnostic criteria.
Only nine cases of the coexistence of VKH and psoriasis have been reported.[2-4] Vitiligo was noted in five cases, and in most of these, psoriasis was confined to the vitiliginous areas. Autoimmune diseases were noted in two cases.
Interestingly, only our case involved vitiligo preceding psoriasis. Although their concurrence may be coincidental, T-cell-mediated autoimmunity may play a role in their onset. Recognition of tyrosinase and gp100 melanocyte antigens by CD4+ T lymphoctes and recognition of MART-1 melanocyte antigen by cytotoxic T lymphocytes have been reported in VKH patients. A recent study has shown that T-helper (Th)17 cell-related cytokines affect melanocyte function in addition to CD8+ cell-mediated melanocyte destruction in vitiligo. Th17 cells and regulatory T cells (Treg) are known to play important roles in the pathogenesis of psoriasis. In VKH lesions, increased Th17 response and decreased frequency and function of Treg have been reported. It has been suggested that the vitiliginous lesions in VKH triggered psoriasis through these T-cell-mediated mechanisms.
In conclusion, we reported an atypical instance of VKH, with vitiligo preceding the psoriasis. Further accumulation of cases may help elucidate the relationship between these two diseases.