A comparative study of histopathological findings in psoriatic lesions with and without treatment Deepti Arora, Faiyaz Ahmad, Ankita Mittal, Ashutosh Kumar, Seema Awasthi, Shyamoli Dutta Acta Medica International 2019 6(1):2-6 Background: Psoriasis is a multifactorial chronic relapsing inflammatory dermatological disorder associated with significant comorbidities. It is characterized by sharply demarcated, erythematous papules, and plaques with abundant silvery-white scales. Due to its variable clinical presentation, histopathology remains the mainstay of diagnosis. However, these histologic features changes with treatment and may also guide in therapeutic decision-making. Aim: The aim is to evaluate and compare the histopathological features of psoriatic lesions before treatment with those receiving treatment for psoriasis. Patients and Methods: A total of 101 biopsies from selected consecutive patients of histopathologically confirmed psoriasis vulgaris were included in the study. These cases were then divided into two groups, Group A includes cases who never received treatment and Group B, those receiving treatment for psoriasis. These biopsies were histopathologically analyzed and compared for various morphological features. Results: Of 101 cases of psoriasis, 72 cases were included in Group A and 29 were included in Group B. Biopsies of Group A showed parakeratosis and acanthosis as a common feature in all of them with dilated or abnormal capillary pattern in dermal papillae in 93.1%. In Group B, in spite of uniform parakeratosis as noticed in Group A biopsies, focal parakeratosis was seen in 83.3%, acanthosis in 87.5%, and dilated/abnormal capillary pattern in dermis was observed to be a universal feature in biopsies of Group B. All other microscopic features of psoriasis also decreased in frequency in Group B. However, statistically significant difference is seen only in changes in morphological features of superficial epidermis that is, parakeratosis, acanthosis, and absent or decreased granular layer in both the groups. Conclusion: Treatment may lead to improvement in the histologic features in epidermis with significant difference in few of them. However, abnormal vasculature in the dermal papillae persists and does not show any improvement with therapy.