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Pathology- Psoriasis
Definition • A chronic, recurrent dermatological condition characterized by aberrant hyperproliferation of the epidermis. Epidemiology • Prevalent, impacting approximately 2% of the population. • Average age of onset is 25 years.
Aetiology Current evidence indicates that psoriasis arises from an aberrant immune response to an environmental trigger in a genetically predisposed individual. • Factors recognized to provoke or intensify the disease encompass stress, infections, climate, alcohol consumption, smoking, and trauma. Genome-wide linkage study has identified a minimum of nine chromosomal loci linked to psoriasis, predominantly comprising genes that encode HLA proteins, cytokines, or cytokine receptors.
Pathogenesis Activated plasmacytoid dendritic cells in the skin travel to draining lymph nodes, where they facilitate the differentiation of naïve T-cells into type 1 and type 17 helper and cytotoxic T-cells. Effector T-cells migrate to the skin, where they produce cytokines such as IL-17, IL-22, IFN-γ, and TNF-α, which promote the hyperproliferation of epidermal keratinocytes. The typical presentation of psoriasis features well-defined erythematous oval plaques adorned with adhering silvery scales. The preferred locations are the elbows, knees, and scalp. Nail involvement frequently presents with pitting and onycholysis.
Guttate psoriasis is a clinical variation distinguished by tiny, erythematous papules measuring 1–5mm in size. Numerous instances are preceded by streptococcal infection. Severe psoriasis can lead to erythroderma (erythrodermic psoriasis).
Histopathology Typical lesions exhibit psoriasiform epidermal proliferation accompanied by thinning of the suprapapillary plates. Plaques of parakeratosis exhibit a reduction of the granular layer underlying the parakeratosis. Collections of neutrophils are observed in the stratum corneum (Munro microabscesses) and may also be present inside the stratum spinosum. The dermis comprises dilated capillaries and an inflammatory infiltrate. Prognosis • Typically follows a chronic trajectory. • Can substantially affect quality of life.
Definition • A chronic, recurrent dermatological condition characterized by aberrant hyperproliferation of the epidermis. Epidemiology • Prevalent, impacting approximately 2% of the population. • Average age of onset is 25 years.
Aetiology Current evidence indicates that psoriasis arises from an aberrant immune response to an environmental trigger in a genetically predisposed individual. • Factors recognized to provoke or intensify the disease encompass stress, infections, climate, alcohol consumption, smoking, and trauma. Genome-wide linkage study has identified a minimum of nine chromosomal loci linked to psoriasis, predominantly comprising genes that encode HLA proteins, cytokines, or cytokine receptors.
Pathogenesis Activated plasmacytoid dendritic cells in the skin travel to draining lymph nodes, where they facilitate the differentiation of naïve T-cells into type 1 and type 17 helper and cytotoxic T-cells. Effector T-cells migrate to the skin, where they produce cytokines such as IL-17, IL-22, IFN-γ, and TNF-α, which promote the hyperproliferation of epidermal keratinocytes. The typical presentation of psoriasis features well-defined erythematous oval plaques adorned with adhering silvery scales. The preferred locations are the elbows, knees, and scalp. Nail involvement frequently presents with pitting and onycholysis.
Guttate psoriasis is a clinical variation distinguished by tiny, erythematous papules measuring 1–5mm in size. Numerous instances are preceded by streptococcal infection. Severe psoriasis can lead to erythroderma (erythrodermic psoriasis).
Histopathology Typical lesions exhibit psoriasiform epidermal proliferation accompanied by thinning of the suprapapillary plates. Plaques of parakeratosis exhibit a reduction of the granular layer underlying the parakeratosis. Collections of neutrophils are observed in the stratum corneum (Munro microabscesses) and may also be present inside the stratum spinosum. The dermis comprises dilated capillaries and an inflammatory infiltrate. Prognosis • Typically follows a chronic trajectory. • Can substantially affect quality of life.
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