[Pathological characteristics of pigmented pretibial patches and vascular-immune abnormalities in diabetic patients].

OBJECTIVES: To explore pathological and immune cell infiltration characteristics of pigmented pretibial patches in diabetic patients. METHODS: Forty-two diabetic patients undergoing thigh amputation at Tianjin Medical University Chu Hsien-I Memorial Hospital were enrolled. Before the operation, the pretibial skin of the patients were examined and sampled for HE and Masson staining. The thickness of the epidermis and the density of blood vessels in the dermis were compared between patients with and without pigmented pretibial patches. The expressions of VEGFA and VEGFR2 in the skin tissues were detected using Western blotting, and CD4+ and CD8+ cells and the CD4/CD8 ratio were analyzed with immunohistochemical staining. RESULTS: Compared with the patients without pigmented pretibial patches, the patients with pigmented pretibial patches showed obvious thickening of the epidermal spinous layer, irregular downward extension of the epidermal projections, hyperkeratosis, melanin deposition in the basal layer, increased capillaries in the dermis, and localized, well-defined inflammatory cell infiltration around the blood vessels. In pigmented pretibial patches group, Masson staining revealed irregular arrangement, thickening and hyaline degeneration of collagen fibers, significantly increased epidermal thickness and blood vessel density in the dermis, increased CD4+ cells and the CD4/CD8 ratio, and reduced CD8+ cells. CONCLUSIONS: The pigmented pretibial patches in diabetic patients show obvious pathological changes possibly due to vascular and immune abnormalities.