Vitiligo and psoriasis: Coexistence with colocalization

Arun C Inamadar, VV Sampagavi, SB Athanikar, MN Patil, NS Deshmukh

 Department of Dermatology, Venereology & Leprosy BLDEA's SBMP Medical College, Bijapur - 586 103, India

Correspondence Address:
Arun C Inamadar
Department of Dermatology, Venereology & Leprosy BLDEA's SBMP Medical College, Bijapur - 586 103
India

Introduction

Vitiligo has been associated with many conditions.[1] Anatomical co-habitation of psoriasis and vitiligo has been reported.[2],[3] A case of long standing vitiligo, developing psoriasis, with few co-habitation lesions and new conclusions are reported herein.

Case Report

A 20-year-old male was on PUVA therapy for vitiligo vulgaris since one year. Patient noticed red, scaly elevated skin lesions for the past 2 months. Cutaneous examination revealed well defined, erythematous papules and plaques with silvery white scales over scalp and extremities. At places there was co-habitation of psoriatic lesions over vitiligo patches [Figure - 1]. Auspitz sign was positive. A clinical diagnosis of coexistent vitiligo and psoriasis was made. Skin biopsy was done from colocalized lesion. HPE revealed hyperkeratosis, parakeratosis, hypogranulosis, and elongation of rete ridges with suprapapillary thinning of the epidermis. There was an absence of melanocytes in the basal cell layer, confirmed by special stainig. Perivascular lymphocytic infiltration was noted in the dermis. The features were consistent with colocalized vitiligo and psoriasis.

Discussion

It is not suprising to see association of vitiligo and psoriasis as they affect 1% to 3% of the population normally.[4],[5] The hypothesis that generalised vitiligo is an autoimmune process is based principally on its association with other presumably immunologic disorders4 and demonstration of antimelanocyte antibody.[6] The serendipitous observation that treatment with cyclosporine dramatically improved psoriasis[7] provided the first strong evidence that the disorder had an immune cause and there is increasing support for the idea that psoriasis is a T cell mediated autoimmune disease.[8] Co-habitation of two disorders which possess a prominent immunological component in their pathogenesis may offer a clue as to their causation, although such hopes have not been fulfilled in the earlier cases reported.[2],[3]

The curious cohabitation of a psoriatic lesion over a PUVA treated vitiligo patch in our patient has raised speculation on the role of T-cell activation in the development and persistence of psoriatic lesions. PUVA greatly reduces the number of activated T cells in the psoriatic skin by inducing T cell apoptosis, often resulting in long standing remissions.[9] So our patient should not have developed psoriatic lesions on the PUVA treated vitiligo patch. This paradox can be explained by the clinical heterogenicity of psoriasis, the apparent multigenic pattern of inheritance and a combination of variables involved in the development of psoriasis.

An alternative explanation can be on the basis of Koebner phenomenon, which is consistent with the immune surveillance paradigm.[10] PUVA destroys keratinocytes, lymphocytes and fibroblasts in culture.[4] Preformed interleukin 1 alpha is released from keratinocytes after minor trauma[11] (? PUVA in the present case). Cutaneous lymphocyte antigen (CLA) positive T cells are recruited from peripheral blood by interleukin 1 alpha initiated inflammation, and CLA positive T cells whose antigen receptor is specific for the putative psoriatic auto antigen in skin will be activated insitu. The subsquent release of type 1-Tcell cytokines results in further inflammation, the recruitment of additional CLA positive T cells, and ultimately the development of psoriatic lesion in susceptible persons.[12]

Dhar et al[13] conclude that, there could be structural similarities between anti stratum corneum antibodies and anti melanocyte antibodies and also a common neuropeptide might be responsible for cohabitation of vitiligo and psoriasis.

In conclusion, we report the co-existence of vitiligo and psoriasis with few colocalized lesions. Many pigment cell biologists and dermatologists have concluded that vitiligo is an autoimmune disease and psoriasis, the T cell mediated skin disease, may be associated. Whether their interpretation of the association is valid is uncertain. This requires further insight into their pathogenesis, as we believe that psoriasis and vitiligo are spectra of diseases with varied etiology for varied clinical presentation.

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