Skin

Abstract Psoriasis is a common inflammatory skin disease with an incompletely understood etiology. The disease is characterized by red, scaly and well-demarcated skin lesions formed by the hyperproliferation of epidermal keratinocytes. This hyperproliferation is driven by cytokines secreted by activated resident immune cells, an infiltrate of T cells, dendritic cells and cells of the innate immune system, as well as the keratinocytes themselves. Psoriasis has a strong hereditary character and has a complex genetic background. Genome-wide association studies have identified polymorphisms within or near a number of genes encoding cytokines, cytokine receptors or elements of their signal transduction pathways, further implicating these cytokines in the psoriasis path mechanism. A considerable number of inflammatory cytokines have been shown to be elevated in lesional psoriasis skin, and the serum concentrations of a subset of these also correlate with psoriasis disease severity. The combined effects of the cytokines found in psoriasis lesions likely explain most of the clinical features of psoriasis, such as the hyperproliferation of keratinocytes, increased neovascularization and skin inflammation. Thus, understanding which cytokines play a pivotal role in the disease process can suggest potential therapeutic targets. A number of cytokines have been therapeutically targeted with success, revolutionizing treatment of this disease. Here we review a number of key cytokines implicated in the pathogenesis of psoriasis.

Granulomatous dermal lesions pose a diagnostic challenge, since several causes can produce an identical histologic picture and, conversely, a single cause may produce varied histologic pattern. The aim of this study is to analyze the spectrum of various etiologies involved in granulomatous skin diseases and their clinicopathological correlation. Cases of granulomatous lesions reported over last one year on histopathological and cytological examination were reviewed along with special stains. A total of 20 cases of different etiologies were taken for study including infectious and non-infectious underlying causes. Out of the 20 dermal granulomatous lesions studied, 12 cases (60.0%) were bacterial, 1 case (5%) each of fungal and associated with malignancy and 6 cases (30%) due to non-infectious etiology like granuloma annulare and foreign body associated were recorded. Amongst the bacterial granulomatous lesions, predominance of Mycobacterium leprae was seen, 6 cases (40%). The varied presentation of Hansen’s disease in our study included 4 cases (20%) of tuberculoid leprosy and 2 cases (10%) each of lepromatous leprosy and borderline tuberculoid leprosy. Three cases (15%) of cutaneous tuberculosis seen in our study and were typified as lupus vulgaris, 2 cases (10%) and a single case (5%) of tuberculosa verrucosa cutis. One case, (5%) of Klebsiella rhinoscleromatis was also seen. Skin biopsies help in arriving at a conclusive diagnosis, if aided by a proper clinical history and examination and assisted by special stains, culture of organisms, PCR and immunoflourescence.