Hair Transplant and Hair Loss Glossary

To help non-medical users navigate this website and comprehend the different medical jargon used by our center, we’ve created this list of hair loss and hair transplant terminology. The definitions offered are meant to provide a straightforward explanation of these phrases and act as a quick reference; they are not meant to be overly scientific in nature. Instead, they are presented in a more casual manner.

Alopecia:
The term “alopecia” is used to describe any type of hair loss, whether it’s male or female pattern, scarring, or otherwise (refer to Male-Pattern Hair Loss, Female Pattern Hair Loss, and Scarring Hair Loss). However, many people use this term to refer to a specific type of alopecia called “alopecia areata,” which is technically inaccurate (see Alopecia Areata).

Alopecia Areata:
Alopecia areata is an immune-mediated type of hair loss that typically appears as circular patches of hair loss on the scalp, although it can progress to more widespread hair loss that affects the entire scalp (see Alopecia Totalis), as well as eyebrows and body hair (see Alopecia Universalis). Although the cause of this type of hair loss is fully understood, it is believed that there is genetic susceptibility and environmental triggers leading to an autoimmune attack of the hair follicle. Hair transplant surgery is not an appropriate solution for this type of hair loss. Rather, it is best addressed with topicals, intralesional steroid injections, or oral medications that are typically managed by a dermatologist.

Alopecia Totalis:
Alopecia areata that involves loss of all scalp hair.

Alopecia Universalis:
Alopecia areata that involves loss of all body hair (including scalp and non-scalp)

Anagen:
Describes hair follicles in the active growth phase of the hair cycle. During this phase, the hair shaft is elongating and the hair is firmly anchored in the scalp. The length of the anagen phase can vary depending on factors such as genetics and age, and can impact the overall length and thickness of the hair. Typically this is 2-3 years, but can be as short as a few months under certain circumstances.

Androgenetic Alopecia:
This is a medical term used to refer to the most common type of hair loss in men, so called male-pattern hair loss (refer to Male-Pattern Hair loss). It is a chronic condition characterized by the progressive loss of terminal hairs on the scalp in a characteristic distribution, under the influence of androgen hormones. This term has been used to refer to women with hair loss, but has been largely replaced by female-pattern hair loss (see Female-Pattern Hair Loss).

Avodart:
This is the trade name for Dutasteride (refer to Dutasteride).

Bulge:
The “bulge” refers to the middle part of the hair follicle that contains the highest concentration of stem cells, which are critical for hair regeneration and growth. It is essential to ensure that this area is not damaged during graft dissection or placement. In scarring alopecia, damage to the bulb is what leads to permanent hair loss.

Catagen:
This describes hairs in the transitional phase between the anagen growth phase and the telogen resting phase. During catagen, the hair follicle begins to shrink and detach from the hair shaft, which stops growing. This phase typically lasts for a few weeks and marks the end of the active growth period before the hair enters the resting phase.

Central Forelock:
The area of the scalp located in the midline just behind the hairline is called the central forelock, and ensuring sufficient hair density in this area is crucial for achieving an aesthetically appealing result.

Central Centrifugal Cicatricial Alopecia (CCCA):
Also called CCCA, is a type of scarring hair loss that primarily affects people (specifically women) of African descent and typically occurs in the crown or back of the head and expands centrifugally (See Scarring Hair Loss.)

Dermal Papilla:
The dermal papilla is the bottom part of the hair shaft with significant regenerative capacity for the hair follicle. During hair transplantation, it is essential to keep it intact to avoid damage to the hair follicle.

Dihydrotestosterone (DHT):
DHT is responsible for male-pattern baldness in hairs that are sensitive to it, usually occurring in the front, top, and crown of the scalp. This hormone is formed when testosterone is converted to DHT by 5-alpha-reductase enzyme. It is not known if this hormone is also responsible for female-pattern hair loss.

Di-Follicular Unit Graft (DFU):
A graft consisting of two closely spaced follicular units.

Donor Area:
The area in the back of the head where hair grafts are harvested for transplantation is known as the donor area, and the safe donor area is the area that can be harvested without significant risk of future hair loss based on the principle of donor dominance. This principle states that hairs taken from the safe donor area, where hairs are not predisposed miniaturization, will not become susceptible to hair loss even when transplanted to the front or top of the head, an area that is otherwise prone to hair loss.

Diffuse Unpatterned Alopecia (DUPA):
DUPA is miniaturization that affects not only areas typically sensitive to DHT but also involves the donor area. Miniaturization exceeding 15 to 20% in the donor area is a reason not to perform a hair transplant since the transplanted hairs may be lost over time.

Dutasteride:
An oral medication used off-label to treat significant cases of male-pattern hair loss. It blocks both type 1 and type 2 5 alpha-reductase, which has an almost complete blockade of DHT, the cause of male-pattern baldness, but has a potentially more significant side-effect profile than finasteride. It is also available in a topical and intralesional formulation.

Female-Pattern Hair Loss:
This describes the genetic predisposition of women to lose hair, typically caused by hormonal influences (but not necessarily DHT). Unlike androgenetic alopecia in men (male pattern hair loss), the loss of terminal hairs in affected areas is usually incomplete and the frontal hairline is often spared.

Finasteride:
This is an FDA-approved oral medication taken by men (and in some cases post-menopausal women, which is off-label) to slow down androgenetic alopecia. The medication works by inhibiting the 5-alpha reductase type 2 enzyme, which blocks the conversion of testosterone to dihydrotestosterone (DHT) and typically blocks about 60 to 70% of DHT. It is also available in a topical formulation.

Follicle:
The hair shaft and epithelium and its accompanying structures, including the arrector pili muscle, sebaceous gland, and related adnexa.

Follicular Units:
Hair on the scalp grows in clusters known as follicular units, which are composed of 1-5 hairs, which are then divided into individual grafts known as follicular-unit grafts. These grafts are what are transplanted, whether performed via FUE or FUT procedure.

Front Fibrosing Alopecia (FFA):
FFA is a type of scarring hair loss affecting the frontal hairline and eyebrows, most commonly of postmenopausal women. Patients may also develop small, skin-colored facial papules on the cheeks, chin, or temples. It is postulated to be a subtype of lichen planopilaris

Fronto-Temporal Recession:
This refers to the loss of hair along the frontal and temporal hairline, which is a key feature of male pattern baldness or androgenetic alopecia (refer to Androgenetic Alopecia for more details). This type of hair loss usually appears earliest in individuals with a Norwood II or III pattern of baldness (refer to Norwood Classification). While fronto-temporal recession is common among both Asians and Caucasians, it is less frequently observed in African-Americans who typically maintain a more prominent right angle in the fronto-temporal region, and experience a gradual, uniform loss of the hairline.

Follicular Unit Extraction (FUE):
FUE is a hair transplant technique primarily used for men who want to maintain a closely-worn haircut without the visibility of a linear scar. FUE involves harvesting individual follicular units one at a time with a round punch.

Follicular Unit Transplant (FUT):
FUT involves harvesting hairs from the back of the head using a linear excision. FUT permits maximal hair harvesting for extensive hair loss and does not require preoperative hair shaving, but may result in a visible linear scar.

Graft:
Composed of a single follicular unit, a graft is individually placed into recipient sites during a hair transplant procedure.

Hair Cloning:
Although the term “hair cloning” is technically incorrect and has not yet been achieved, it refers to the hope that in the future, advanced techniques will allow for an unlimited supply of transplantable hair from the donor area.

Hair Curl:
The natural curl of each hair is directed toward the scalp as it emerges from the skin.

Hair System:
A hairpiece, typically for men, made of human hair that is woven through a laced mesh to appear as natural hair growing from the scalp. A cap hair system extends down the sides of the head while a standard hair system is attached to existing hair through clips or adhesive. A wig is the female equivalent of a cap hair system. Hair transplant surgery can be used to transition out of a hair system, reduce the size of a hair system, or match the hairline of a hair system in the temple region.

Lateral Hump:
The subregion of the scalp on the sides of the head that must be recreated in cases of advanced baldness.

Lichen planopilaris (LPP):
LPP is a type of scarring hair loss characterized by the formation of red, scaly patches on the scalp that may progress over time to complete hair follicle loss. The exact cause of lichen planopilaris is not fully understood, but it is thought to involve a combination of genetic, autoimmune, and environmental factors.

Ludwig Scale:
A scale for grading female hair loss that ranges from Grade 1 for early diffuse loss to Grade 3 for significant diffuse hair loss.

Male-Pattern Hair Loss:
Androgenetic alopecia, a type of hair loss caused by hair follicles that are sensitive to the effects of DHT and are usually lost over time in the frontal, central, and crown regions of the head (see Androgenetic alopecia). By some measures, nearly 50% of men between 18 and 50 years of age experience at least a moderate amount of this type of hair loss.

Midscalp:
The subregion of the scalp between the central forelock and vertex transition zone.

Miniaturization:
This is the process by which thick, terminal hairs gradually become thinner, wispier, and more transparent (miniaturized or vellus hairs) in patterned hair loss, leading to eventual complete baldness.

Minoxidil:
A medication used to slow down and potentially reverse male and female-pattern hair loss increasing the duration of anagen, shortening telogen, and enlarging miniaturized follicles. Available over-the-counter in a topical formulation, it is sold as Rogaine in the US and Regaine in Europe. Minoxidil comes in 2% and 5% dosages, with the latter used for both men and women. There are specialized compounded topical versions of minoxidil that can enhance its efficacy. Oral formulation is becoming increasingly popular, and an intralesional formulation is also available.

Norwood Classification:
The Hamilton-Norwood scale is a system for documenting the degree of male hair loss, which breaks it down into 7 sequential stages with corresponding visual representation. It also serves as a template for designing a hair pattern that mimics nature.

Plugs:
An outdated term used to describe hair transplant grafts. Old plugs were 4-mm round punch grafts containing 16 to 20 hairs, but today, single follicular units are used as grafts instead of plugs which gives a superior aesthetic result.

Propecia:
The trade name for oral finasteride, which is used to treat male-pattern baldness.

Recipient Dominance:
The phenomenon in which transplanted hair grafts typically preserve their donor characteristics, but may be influenced by the recipient area. For example, hairs transplanted from the scalp to the eyebrows may start to slow down their growth after 1 to 2 years to resemble the pattern of natural eyebrow hairs.

Recipient Sites:
These are small holes made with specialized blades or needles to insert grafts (See Grafts).

Safe Donor Area (SDA):
It refers to the area at the back and sides of the head that are considered safe to be used as a source of grafts for transplant because hair from this area, even when transplanted to a new location, will not be lost in the future due to donor dominance (See Donor Dominance).

Scarring Alopecia:
A type of hair loss where the hair follicles are eventually lost and replaced with scars. Examples include central centrifugal cicatricial alopecia (CCCA), lichen planopiliaris (LPP), frontal fibrosing alopecia (FFA), and discoid lupus erythematosus (DLE). In general these are managed with medical therapy and transplants have limited efficacy (See CCCA, LPP,  FFA, and DLE).

Shock Loss:
This refers to a temporary hair shedding that may occur weeks to months after a hair transplant due to the trauma of the procedure or the use of epinephrine. Women are more likely to experience it, but it can be minimized (not entirely avoided) by using medications like minoxidil (see Minoxidil) for at least 4 to 6 weeks before the procedure (see Telogen Effluvium).

Slivering:
After removing a donor strip of tissue during an FUT procedure (see FUT), the strip is breadloafed into a single sheet layer of hair follicles, which is called slivering. These slivers are further dissected into individual grafts consisting of individual follicular units (see Follicular Unit).

Scalp Micropigmentation (SMP):
This refers to temporary or permanent tattooing of the scalp, where the tiny tattoo marks simulate hair follicles. SMP can be used to minimize donor scars or to add further visual hair density to an individual with or without hair transplant surgery.

Telogen:
Describes hairs that are in the resting phase of the hair cycle. During this phase, the hair is no longer growing and is preparing to shed from the scalp. It is normal to have a certain percentage of telogen hairs at any given time, but excessive shedding or an increased proportion of telogen hairs can be a sign of an underlying condition. The length of the telogen phase can vary, but typically lasts around 3 months before the hair is shed and the cycle starts anew.

Telogen Effluvium:
It is a type of hair loss characterized by increased air shedding, but rarely frank baldness. It occurs when hairs shift from the growth phase to the resting (telogen) phase, in which the hairs fall out. It usually follows stress on the body such as a surgery, general anesthesia, pregnancy, protein-malnourished weight loss, or general sickness, typically appearing about 3 months after the event. Shock loss (See Shock Loss) that follows a hair transplant surgery is caused by telogen effluvium.

Temporal Point:
It refers to the triangular point of hair in the temporal region of the scalp, which can be reconstructed to provide a better total frame to the frontal hairline.

Terminal Hairs:
These are the thick hairs one possesses before the onset of patterned hair loss (see Female-Pattern Hair Loss and Male-Pattern Hair Loss). These terminal hairs gradually undergo a process of miniaturization (see Miniaturization) in which they become vellus hairs (see Vellus Hairs) and can eventually be entirely lost leading to apparent baldness.

Traction Alopecia:
This type of hair loss is caused by mechanical pulling/tension on the hair follicle over time, which can eventuate in permanent hair loss. It can be seen in the temples in African-American women who braid or pull their hairs tightly or in Sikh men who wear their hairs tightly turned into a knot under a turban. This type of hair loss is often amenable to hair transplant, whereas it is not amenable to most medical therapies.

Transection:
This refers to the accidental cutting of a hair shaft during hair transplant procedures, such as FUE or FUT. Hairs that are transected are less likely to survive, particularly if the dermal papilla or bulge regions are damaged.

Trichophytic Closure:
A method of wound closure used after FUT donor harvesting, which involves removing 1 mm of epidermis from the bottom edge of the wound. This allows hair to grow through the scar, making it less visible.

Trichotillomania:
A type of obsessive-compulsive disorder in which an individual compulsively pulls out their own hair. If the condition is stable and well-treated, hair transplant surgery may be an option for areas in which the hair will not grow back on its own.

Vellus Hairs:
These are tiny, wispy, transparent hairs that are often seen in the intermediate phase of patterned hair loss. Terminal hairs can become vellus hairs, which can eventually be lost, leading to partial or complete baldness.

Vertex:
This term refers to the crown of the head, which is the posterior part of the head that falls on the vertical plane of the scalp. A crown transplant can be performed in appropriate candidates.

Vertex Transition Zone (Point):
This describes the semilunar line between the midscalp and the crown of the head, marking the transition from the horizontal to the posterior plane of the scalp. It can determine the anterior or posterior limit of a hair transplant.

Whorl:
A circular pattern of hair direction that is typically present in the crown of the head, but can also be observed in certain hairlines or other areas of the scalp.