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Malassezia (Tinea versicolor and Seborrhoeic dermatitis)
Pediculus humanus and Phthirus pubis (Lice)
Sarcoptes scabiei (Scabies)
Human herpesvirus 6 (Roseola)
Varicella zoster virus
Herpes simplex virus
Poxvirus (Smallpox and Molluscum contagiosum)
Varicella zoster virus
Acneiform skin disorders: Pathology review
Bacterial and viral skin infections: Pathology review
Papulosquamous and inflammatory skin disorders: Pathology review
Pigmentation skin disorders: Pathology review
Skin cancer: Pathology review
Vesiculobullous and desquamating skin disorders: Pathology review
Viral exanthems of childhood: Pathology review
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Stevens-Johnson syndrome p. 494
as drug reaction p. 251
sulfa drug allergies p. 253
Both can be fatal if not treated, and the risk of fatality increases with severity.
The skin plays an important role in protecting underlying muscles, bones, ligaments, and internal organs by forming a barrier to infectious pathogens; and preventing water loss from the body.
The outermost layer of the skin is the epidermis and, itself, is made of several layers of cells.
The deepest layer is called the stratum basale, or the base layer.
And cells here are anchored to a basement membrane, a thin layer of delicate tissue containing proteins like collagen and laminins, which attach the epidermis to the underlying skin layer called the dermis.
Similar to how the skin lines the outside of the body, mucous membranes, or mucosa, line the inner body surfaces like the mouth, tongue, respiratory tract, conjunctiva of the eyes, genitals, and anus.
Mucosa is made up of one or more layers of epithelial cells, which, again, are attached to a basement membrane that sits on top of a layer called the lamina propria.
This protein presents peptides from within the cell to immune cells called cytotoxic T cells, also called a CD8+ T cells.
If the cell is healthy, the cytotoxic T cell doesn’t recognize the peptides as foreign, and nothing happens.
But if a cell is infected, say with a virus, the cytotoxic T cell can recognize the peptides as foreign and trigger an immune response.
Once all infected cells have been destroyed, the immune response resolves.
Stevens �Johnson syndrome is a life-threatening skin condition, in which cell death causes the epidermis to separate from the dermis. It is a type of IV hypersensitivity reaction where cytotoxic T-cells inappropriately attack and kill epithelial cells in the mucosa and skin epidermis. The most well-known causes are medications, such as lamotrigine and other seizure drugs. Treatment includes immediately removing the trigger, followed by pain medication, hydration, and sterile wound care.
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