Isomorphic phenomenon in discoid lupus erythematosus with review of reported cases.

Abstract

We read with great interest the article by Longhi et al. [1] in which they have reported a patient of systemic lupus erythematosus who developed lesions of discoid lupus erythematosus (DLE) at the site of healed herpes zoster as isomorphic phenomenon. We present a case of disseminated DLE who developed linear DLE lesions at the site of trauma. A 42-year-old man suffering from DLE for the last 2 years had lesions distributed over the face, upper limbs, and the lower limbs including soles. Lesions were in the form of lichenoid hyperpigmented plaques with center showing depigmentation and scarring. He had DLE lesions in oral cavity which were distributed mainly over the palate. His hair and nail were normal. The patient complained of photosensitivity but did not have fever, joint pains, or any other systemic illness at this presentation. Four months back, he had linear laceration near the base of right thumb from kitchen knife. The wound healed over next 10 days. Two months later, he noticed development of scaling and erythema over the linear scar. On examination, there was a linear scar present on the dorsal surface of the right thumb (3 cm 9 0.5 cm). Overlying the scar was erythema, depigmentation and whitish adherent scales (Fig. 1). Skin biopsy done from the linear lesion showed mild hyperkeratosis and hypergranulosis, basal cell vacuolization, and dense mononuclear infiltrate in the dermis (Fig. 2). His complete blood cell count, liver function tests, renal function tests, urine routine examination, 24-h urinary protein and chest X-ray did not reveal any abnormality. His anti-nuclear antibody titers and ds DNA titers were not significant. Koebner phenomenon or isomorphic phenomenon was first described by Heinrich Koebner in psoriasis patients [2]. Since then, it has been reported in various dermatoses though classically seen in psoriasis, lichen planus, and vitiligo. Isomorphic phenomenon indicates the development of typical skin lesions of an existing dermatoses at the site of injury. The case reported by Longhi et al. developed lesions at the site of healed herpes zoster. Our case clearly demonstrates Koebner phenomenon as this patient of DLE developed cutaneous lesions at the site of simple trauma. There are only few case reports of Koebner phenomenon in DLE. Boyd Nelder classified Koebner response into four categories (category I-true Koebner response; category II-pseudo Koebner response; category IIIoccasional lesions; category IV-poor or questionable trauma-induced process) based on the evidence available in the literature [3]. DLE has been classified into category IV as there are few single reports with some having little substantiation of a koebnerization [4]. Literature search revealed only four case reports of Koebner phenomenon in DLE following simple trauma [5–8]. Most recent report is that by Ruocco et al. [8] in which the patient developed lesions distributed in linear pattern in preauricular area, at the site of previous injury. The time interval between trauma and appearance of skin lesion was reported to be 25 years. S. Yadav R. Kumar S. Dogra (&) Department of Dermatology, Venereology and Leprology, Postgraduate Institute of Medical Education and Research, Chandigarh 160 012, India e-mail: sundogra@hotmail.com