00:00 / 00:00
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)
Human herpesvirus 8 (Kaposi sarcoma)
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
0 / 11 complete
0 / 2 complete
erythema multiforme p. 490
erythema multiforme p. 149
Erythema multiforme is an acute, immune-mediated condition that affects skin and mucous membranes such as the mouth and genitals.
The skin is the largest organ in our body, and it’s divided into three layers - the epidermis, dermis, and hypodermis.
The epidermis forms the thin outermost layer of skin.
Underneath, is the thicker dermis layer.
And finally, there’s the hypodermis, the deepest layer.
The epidermis itself is made of multiple layers of developing keratinocytes - which are flat pancake-shaped cells that are named for the keratin protein that they make.
Keratinocytes start their life at the lowest layer of the epidermis called the stratum basale, or basal layer, which is made of a single layer of stem cells called basal cells that continually divide and produce new keratinocytes.
These new keratinocytes then migrate upwards to form the other layers of the epidermis, such as the spinous and granular cell layers.
Below the epidermis is the basement membrane which is a thin layer of delicate tissue containing collagen, laminins, and other proteins.
Basal cells are attached to the basement membrane, and help form the dermoepidermal junction.
Similar to how the skin lines the outside of the body, mucosa lines the inside of the body. And it’s named for the surface it covers.
So there’s oral mucosa, nasal mucosa, bronchial mucosa, gastric mucosa, and so forth.
Mucosa is made up of one or more layers of epithelial cells that sits on top of a layer of connective tissue called lamina propria.
Just like with the skin, there is a basement membrane that sits between and attaches the epithelial layer and the lamina propria.
Now, basal epithelial cells, as well as most cells in the body, have a protein called major histocompatibility complex or MHC class I molecule on the surface of their membrane. This protein presents peptides from within the cell to immune cells called cytotoxic T cells.
If a cytotoxic T cell recognises the peptides as foreign, for example like in a virally infected cell, then the cytotoxic T cell will kill the presenting cell.
Erythema multiforme is an immune-mediated skin condition that typically causes red, itchy patches on the skin. It can also affect the mucous membranes of the mouth and genitals; in some cases, the patches can blister and form lesions. Erythema multiforme is commonly triggered by a Mycoplasma or Herpes simplex virus infection. Some drugs can also cause it, such as penicillins, ciprofloxacin, and anticonvulsants such as carbamazepine.
Latest on COVID-19
Nurse Practitioner (NP)
Physician Assistant (PA)
Create custom content
Raise the Line Podcast
Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
Terms and Conditions
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.