Alopecia areata is believed to be an autoimmune disease resulting from a breach in the immune privilege of the hair follicles. Risk factors include a family history of the condition. Among identical twins, if one is affected, the other has about a 50% chance of also being affected. The underlying mechanism involves failure by the body to recognize its own cells with subsequent immune-mediated destruction of the hair follicle.
Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress.
The hair follicle is an organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells. This complex interaction induces the hair follicle to produce different types of hair as seen on different parts of the body. For example, terminal hairs grow on the scalp and lanugo hairs are seen covering the bodies of fetuses in the uterus and in some newborn babies. The process of hair growth occurs in distinct sequential stages. The first stage is called anagen and is the active growth phase, telogen is the resting stage, catagen is the regression of the hair follicle phase, exogen is the active shedding of hair phase and lastly kenogen is the phase between the empty hair follicle and the growth of new hair.
Telogen effluvium is a scalp disorder characterized by the thinning or shedding of hair resulting from the early entry of hair in the telogen phase. It is in this phase that telogen hairs begin to shed at an increased rate, where normally the approximate rate of hair loss is 125 hairs per day.
Alopecia universalis(AU), also known as alopecia areata universalis, is a medical condition involving the loss of all body hair, including eyebrows, eyelashes, chest hair, armpit hair, and pubic hair. It is the most severe form of alopecia areata.
Tinea capitis is a cutaneous fungal infection (dermatophytosis) of the scalp. The disease is primarily caused by dermatophytes in the genera Trichophyton and Microsporum that invade the hair shaft. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern, that may be accompanied by inflammation, scaling, pustules, and itching. Uncommon in adults, tinea capitis is predominantly seen in pre-pubertal children, more often boys than girls.
Vellus hair is short, thin, light-colored, and barely noticeable hair that develops on most of a person's body during childhood. Exceptions include the lips, the back of the ear, the palm of the hand, the sole of the foot, some external genital areas, the navel, and scar tissue. The density of hair – the number of hair follicles per area of skin – varies from person to person. Each strand of vellus hair is usually less than 2 mm long and the follicle is not connected to a sebaceous gland.
Traction alopecia is a form of alopecia, or gradual hair loss, caused primarily by pulling force being applied to the hair. This commonly results from the sufferer frequently wearing their hair in a particularly tight ponytail, pigtails, or braids. It is also seen occasionally in long-haired people who use barrettes to keep hair out of their faces. Traction alopecia is recession of the hairline due to chronic traction, or hair pulling, and is characterized by a fringe along the marginal hairline on physical exam. Even though this "fringe sign" is considered a useful clinical marker of this condition, cases of frontal fibrosing alopecia presenting with an unusual retention of the hairline have been described.
The management of hair loss, also known as alopecia or baldness, may include medications and surgery.
Dermatoscopy is the examination of skin lesions with a dermatoscope.
Pattern hair loss is hair loss that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front hairline, loss of hair on the crown (vertex) of the scalp, or a combination of both. Female-pattern hair loss (FPHL) typically presents as a diffuse thinning of the hair across the entire scalp.
Monilethrix is a rare autosomal dominant hair disease that results in short, fragile, broken hair that appears beaded. It comes from the Latin word for necklace (monile) and the Greek word for hair (thrix).
Scarring hair loss, also known as cicatricial alopecia, is the loss of hair which is accompanied with scarring. This is in contrast to non scarring hair loss.
Central centrifugal cicatricial alopecia (CCCA), is a type of alopecia first noticed in African Americans in the 1950s and reported by LoPresti et al. in 1968 as a result of application of petrolatum followed by a stove-heated iron comb. The original theory was that the hot petrolatum would travel down to the hair root, burn the follicle, and after repetitive injury scarring would result. Later CCCA was realized to affect men and women without a history significant for use of such styling techniques. Consequently, the terms "follicular degeneration syndrome" per Sperling and Sau in 1992 and then CCCA per Olsent et al. in 2003 were evolved. Plausible contributing factors may include other African-American styling techniques such as relaxers, tight braids, heavy extensions, certain oils, gels or pomades.
Kinking hair, or acquired progressive kinking, is a skin condition primarily reposted in postpubescent males with androgenetic alopecia, presenting with gradual curling and darkening of the frontal, temporal, auricular, and vertex hairs which, under the microscope, show kinks and twists with or without longitudinal grooving.
Pityriasis amiantacea is an eczematous condition of the scalp in which thick tenaciously adherent scale infiltrates and surrounds the base of a group of scalp hairs. It does not result in scarring or alopecia.
Non scarring hair loss, also known as noncicatricial alopecia is the loss of hair without any scarring being present. There is typically little inflammation and irritation, but hair loss is significant. This is in contrast to scarring hair loss during which hair follicles are replaced with scar tissue as a result of inflammation. Hair loss may be spread throughout the scalp (diffuse) or at certain spots (focal). The loss may be sudden or gradual with accompanying stress.
Antonella Tosti is an Italian physician and scientist with major contributions in the field of dermatology.
Lidia Rudnicka is a Polish-American dermatologist with contributions to the field of scleroderma research, hair diseases and melanoma prevention.
Frontal fibrosing alopecia is the frontotemporal hairline recession and eyebrow loss in postmenopausal women that is associated with perifollicular erythema, especially along the hairline. It is considered to be a clinical variant of lichen planopilaris.
