Alopecia pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Kiran Singh, M.D. [2] Ogechukwu Hannah Nnabude, MD
Overview
The pathophysiology of alopecia is dependent on the type of alopecia.
Pathophysiology
- In the case of alopecia areata, the exact pathophysiology is currently unknown, however, the prevailing hypothesis is that it is as a result of T-cell–mediated autoimmunity. In androgenetic alopecia, both hormonal and genetic factors play a role in the pathogenesis.
- In telogen effluvium, the hair loss may influenced by hormones or stress, or other unknown factors. [1] The dermatophyte infection is responsible for hair loss in tinea capitis. In anagen effluvium, the shedding of hair is under the effect of chemotherapeutic agents. In alopecia mucinosa, the infiltration of the scalp with abnormal lymphocytes is the cause. [2]
Pathogenesis
Pathogenesis is the mechanism by which a certain factor causes disease (pathos = disease, genesis = development). The term can also be used to describe the development of the disease, whether it is acute, chronic, or recurrent. It can also be used to describe whether the disease causes inflammation, malignancy, necrosis etc.
Template Sentences
IF the pathogenesis of the disease is unclear:
- The exact pathogenesis of [disease name] is not fully understood.
- It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
IF the disease is infectious…
- …and the route of transmission is known:
- [Pathogen name] is usually transmitted via the [transmission route] route to the human host.
- Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
IF the disease has a known genetic component:
- [Disease name] is transmitted in [mode of genetic transmission] pattern.
- Genes involved in the pathogenesis of [disease name] include [gene1], [gene2], and [gene3].
IF certain pathology findings are characteristic of the disease:
- On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
- On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Histopathology
In androgenetic alopecia, there are miniaturized hair follicles with an increase in the telogen-to-anagen ratio without inflammatory reaction. In anagen effluvium, there is a decrease in anagen hair without any inflammatory response. Finally, in alopecia mucinosa, there is an infiltrate of the epidermis, dermis, and peribulbar lymphocytic infiltrate mainly anaplastic cells. In patients with alopecia areata, there is a peribulbar lymphocytic infiltrate with a decrease in the ratio of anagen to telogen hair. Telogen effluvium is characterized by an increase in the number of catagen hair. In tinea capitis, there is evidence of fungal infection as under a microscope along with a neutrophilic infiltrate.
References
- ↑ Yu L, Lu Z (2018) Linear alopecia areata. JAAD Case Rep 4 (10):1072-1073. DOI:10.1016/j.jdcr.2018.08.015 PMID: 30511001
- ↑ Davey L, Clarke V, Jenkinson E (2019). "Living with alopecia areata: an online qualitative survey study". Br J Dermatol. 180 (6): 1377–1389. doi:10.1111/bjd.17463. PMID 30501016.