Evaluation of active and stable stages of vitiligo using S-100 and human melanoma black-45 immunostains

Background: Vitiligo is the most prevalent pigmentary disorder occurring worldwide. In most cases, the diagnosis is made by clinical examination alone. The disease status (active/stable) needs to be assessed to make appropriate therapeutic decisions. Objective: The aim of the present study was to evaluate the histopathological and immunohistochemical features in active and stable lesions. Materials and Methods: Biopsies from vitiliginous areas from 50 patients (25 each of clinically active and stable vitiligo); with hematoxylin and eosin, Masson Fontana (MF), S-100, and human melanoma black-45 (HMB-45) stained sections were studied. Results: Age of the patients ranged from 7 to 69 years (mean age: 33.6 ± 15.73 years). Of 50 patients, 27 (54%) were male and 23 (46%) were female. All the cases showed variable degree of basal hypopigmentation. Histopathological findings, epidermal spongiosis, basal vacuolar degeneration, dermal melanophages, and dermal lymphomononuclear cells were commonly observed in active lesions as compared to the stable ones. On MF staining, 23/25 cases (92%) of active vitiligo showed complete loss of basal melanin. Quantitative analysis of HMB-45 immunostaining in stable and active vitiligo revealed mean number of positive melanocytes as 2.52 ± 1.0/high power field (hpf) and 0.08 ± 0.28/hpf, respectively, while on S-100 immunostaining the mean values of positive Langerhans cells were 1.70 ± 0.38/hpf and 7.78 ± 4.11/hpf, respectively. Conclusion: The demonstration of overall reduction in the number of HMB-45-positive melanocytes and increase in S-100-positive Langerhans dendritic cells in the active vitiligo lesions is facilitated by immunohistochemistry. The technique is of immense help in differentiating active and stable stages of vitiligo, thus guiding therapy.