[Lichen sclerosus atrophicus at an insulin injection site: an unusual koebner phenomenon].

Over 30% of diabetic patients develop skin conditions during the course of their disease. The following can occur: a) diseases such as scleredema, bullosis diabeticorum (diabetic bullae), granuloma annulare, waxy skin with limited joint mobility of the fingers, finger pebbling, eruptive xanthomas, yellow skin, and diabetic dermopathy; b) bacterial infections, such as erythrasma, necrotizing fascitis, and malignant external otitis, and mycotic infections, such as mucocutaneous candidiasis and rhinocerebral mucormycosis; and c) reactions to antidiabetic drugs.1 The prevalence of adverse skin reactions to insulin has decreased since the appearance of purified and recombinant forms (50%-60% in the 1950s and 1960s to below 3% in the late 1990s). Allergic reactions are usually seen at the site of injection and can appear as early or late erythema, pruritus, and induration. Lipoatrophy, lipohypertrophy, abscesses, xanthomatosis, bullous eruptions, necrosis, purpura, granulomas, hyperpigmentation, keloids, and amyloidosis can also be found at these sites.2 We describe the case of a woman with type 2 diabetes mellitus who developed lichen sclerosus et atrophicus at the sites on the abdomen where she injected insulin. The patient was a 55-year-old woman with a past history of subtotal thyroidectomy for thyroid follicular adenoma and total hysterectomy with bilateral adnexectomy for endometriosis. She had type 2 diabetes mellitus that had developed 18 years earlier and for which she was started on insulin in 2003. At the time of consultation, the patient was on an insulin regimen of bolus injections of long-acting insulin and short-acting analogs (54 units of insulin glargine in the morning and 6 units of insulin aspart at night), plus metformin and repaglinide. She was referred to our outpatient clinic by her endocrinologist for the assessment of pruritic skin lesions that had appeared 1 year earlier on the abdomen. Physical examination revealed multiple whitish papules with keratotic follicular plugs on both sides of the abdomen, forming 2 indurated plaques with well-defined borders (Figure 1A). In addition, the central area of the lesion located on the right side of the abdomen was blistered and crusted (Figure 1B). A whitish, shiny plaque with intralesional purpuric elements was observed in the perianal area (Figure 2). The patient reported that the lesions on the abdomen appeared in the area where she regularly injected insulin. A biopsy of the lesion was taken from the plaque on the right side of the abdomen. Histopathology revealed a thinned epidermis, a small subepidermal vesicle, edema with homogenization of the collagen fibers, and sparse cellularity in the upper dermis. Follicular plugs and a mild chronic inflammatory infiltrate were observed in the mid dermis (Figure 3). Additional tests—complete blood count, biochemistry, levels of antinuclear and antiextractable nuclear antigen antibodies, thyroid stimulating hormone, protein electrophoresis, immunoglobulin 4. Borras J, Ameijide A, Vilardell L, Valls J, Marcos-Gragera R, Izquierdo A. Trends in cancer incidence in Catalonia, 1985– 2002. Med Clin (Barc). 2008;131(Suppl 1):11-8. 5. Kim HJ, Fay MP, Feuer E.J, Midthune DN. Permutation tests for joinpoint regression with applications to cancer rates. Stat Med. 2000;19:335-51. 6. Thorn M, Ponten F, Johansson AM, Bergstrom R. Rapid increase in diagnosis of cutaneous melanoma in situ in Sweden, 1968– 1992. Cancer Detect Prev. 1998;22:430-7. 7. Roder DM, Luke CG, McCaul KA, Esterman AJ. Trends in prognostic factors of melanoma in South Australia, 1981–1992: implications for health promotion. Med J Aust. 1995;162:25-9. 8. Lee JA. The systematic relationship between melanomas diagnosed in situ and when invasive. Melanoma Res. 2001; 11:523-9. 9. Coory M, Baade P, Aitken J, Smithers M, McLeod GR, Ring I. Trends for in situ and invasive melanoma in Queensland, Australia, 1982–2002. Cancer Causes Control. 2006;17:21-7. 10. Forman SB, Ferringer TC, Peckham SJ, Dalton SR, Sasaki GT, Libow LF, et al. Is superficial spreading melanoma still the most common form of malignant melanoma? J Am Acad Dermatol. 2008;58:1013-20. 11. LeBoit PE, Burg G, Weedon D, Sarasin A. World Health Organisation classification of tumours. Pathology and genetics of skin tumours. Lyon: IARC Press; 2006. 12. Conejo-Mir J, Bravo J, Paz-Pérez JL, Fernandez-Herrera J, Guillen C, Marti R, et al. Día del Euromelanoma. Resultados de las campañas del 2000, 2001 y 2002 en España. Actas Dermosifiliogr. 2005;96:217-21. 13. Cayuela A, Rodríguez-Domínguez S, Vigil E, Conejo-Mir JS. Effect of age, birth cohort and period of death on skin melanoma mortality in Spain, 1975 through 2004. Int J Cancer. 2008;122:905-8.