| Pili multigemini | |
|---|---|
| Other names | Pili gemini [1] |
 | |
| An extracted pilus multigeminus with three distinct hairs growing from the same source. | |
| Specialty | Dermatology |
Pili multigemini, also known as "compound hairs," [2] is a malformation characterized by the presence of bifurcated or multiple divided hair matrices and papillae, giving rise to the formation of multiple hair shafts within the individual follicles. [3] [4]
The name describes a condition where several separate hair fibers bunch together and emerge from the skin through a single hair canal. Pathology shows that deep in the skin several dermal papilla are closely situated with each producing a fiber, but these separate hair follicle bulbs combine into one hair canal towards the skin surface. Folliculitis can sometimes be associated with this condition. [2]
Electrolysis will permanently remove pili multigemini. Depilating laser treatment has been suggested to improve symptomatic pili multigemini. [5]
Folliculitis is the infection and inflammation of one or more hair follicles. The condition may occur anywhere on hair-covered skin. The rash may appear as pimples that come to white tips on the face, chest, back, arms, legs, buttocks, or head.
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: anagen is the active growth phase, catagen is the regression of the hair follicle phase, telogen is the resting stage, exogen is the active shedding of hair phase and kenogen is the phase between the empty hair follicle and the growth of new hair.
A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Surrounding the female nipple, areolar glands are specialized sebaceous glands for lubricating the nipple. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals.
Pseudofolliculitis barbae (PFB) is a type of irritant folliculitis that commonly affects people who have curly or coarse facial hair. It occurs when hair curls back into the skin after shaving, causing inflammation, redness, and bumps. This can lead to ingrown hairs, scarring, and skin discoloration. PFB can be treated with various methods, including changing shaving habits, using topical creams or ointments, and undergoing laser hair removal. Prevention measures include proper shaving techniques, using sharp razors, and avoiding too close a shave.
The arrector pili muscles, also known as hair erector muscles, are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps (piloerection).
Eosinophilic folliculitis is an itchy rash with an unknown cause that is most common among individuals with HIV, though it can occur in HIV-negative individuals where it is known by the eponym Ofuji disease. EF consists of itchy red bumps (papules) centered on hair follicles and typically found on the upper body, sparing the abdomen and legs. The name eosinophilic folliculitis refers to the predominant immune cells associated with the disease (eosinophils) and the involvement of the hair follicles.
Hot tub folliculitis, also called Pseudomonalfolliculitis or Pseudomonas aeruginosa folliculitis, is a common type of folliculitis featuring inflammation of hair follicles and surrounding skin.
Folliculitis decalvans is an inflammation of the hair follicle that leads to bogginess or induration of involved parts of the scalp along with pustules, erosions, crusts, ulcers, and scale. It begins at a central point and spreads outward, leaving scarring, sores, and, due to the inflammation, hair loss in its wake. No permanent cure has been found for this condition, but there is promise in a regimen of dual therapy with rifampin 300 mg twice daily and clindamycin 300 mg twice daily. This new treatment can be used to control the condition, and tests have indicated that after 3 to 5 months long uninterrupted courses of treatment, many patients have seen limited to no recurrence.
Acne miliaris necrotica is a severe form of folliculitis of typically the scalp. It presents as multiple fluid-filled bumps, sometimes occurring as solitary lesions that are usually very itchy. Shortly after appearing, the bumps burst and dry up. There may be scarring.
Pruritic folliculitis of pregnancy is a skin condition that occurs in one in 3000 people, about 0.2% of cases, who are in their second to third trimester of pregnancy where the hair follicle becomes inflamed or infected, resulting in a pus filled bump. Some dermatologic conditions aside from pruritic folliculitis during pregnancy include "pruritic urticarial papules and plaques of pregnancy, atopic eruption of pregnancy, pemphigoid gestationis, intrahepatic cholestasis of pregnancy, and pustular psoriasis of pregnancy". This pruritic folliculitis of pregnancy differs from typical pruritic folliculitis; in pregnancy, it is characterized by sterile hair follicles becoming inflamed mainly involving the trunk, contrasting how typical pruritic folliculitis is mainly localized on "the upper back, shoulders, and chest." This condition was first observed after some pregnant individuals showed signs of folliculitis that were different than seen before. The inflammation was thought to be caused by hormonal imbalance, infection from bacteria, fungi, viruses or even an ingrown hair. However, there is no known definitive cause as of yet. These bumps usually begin on the belly and then spread to upper regions of the body as well as the thighs.
Perforating folliculitis is a skin condition in humans characterized by discrete follicular keratotic eruptions involving mainly the hairy parts of the extremities.
Tufted folliculitis presents with doll's hair-like bundling of follicular units, and is seen in a wide range of scarring conditions including chronic staphylococcal infection, chronic lupus erythematosus, lichen planopilaris, Graham-Little syndrome, folliculitis decalvans, acne keloidalis nuchae, immunobullous disorders, and dissecting cellulitis.
Disseminate and recurrent infundibulofolliculitis, also called disseminate and recurrent infundibular folliculitis or Hitch and Lund disease, is a rare follicular skin condition that presents with irregularly shaped papules pierced by hair, is mildly itchy at times, and is chronic with recurrent exacerbations.
Pili bifurcati is characterized by bifurcation found in short segments along the shafts of several hairs, with each branch of the bifurcation being covered with its own cuticle.
Malassezia folliculitis or pityrosporum folliculitis, is a skin condition caused by infection by Malassezia yeast.
Majocchi's granuloma is a skin condition characterized by deep, pustular plaques, and is a form of tinea corporis. It is a localized form of fungal folliculitis. Lesions often have a pink and scaly central component with pustules or folliculocentric papules at the periphery. The name comes from Domenico Majocchi, who discovered the disorder in 1883. Majocchi was a professor of dermatology at the University of Parma and later the University of Bologna. This disease is most commonly caused by filamentous fungi in the genus Trichophyton.
Sycosis vulgaris is a cutaneous condition characterized by a chronic infection of the chin or bearded region.
Hair follicle nevus is a cutaneous condition that presents as a small papule from which fine hairs protrude evenly from the surface.
Prepubertal hypertrichosis, also known as childhood hypertrichosis, is a cutaneous condition characterized by increased hair growth, found in otherwise healthy infants and children. Prepubertal hypertrichosis is a cosmetic condition and does not affect any other health aspect. Individuals with this condition may suffer with low self esteem and mental health issues due to societal perceptions of what a "normal" appearance should be. The mechanism of prepubertal hypertrichosis is unclear, but causes may include genetics, systemic illnesses, or medications.
Irritant folliculitis is an inflammation of the hair follicle. It characteristically presents with small red bumps in the skin at sites of occlusion, pressure, friction, or hair removal; typically around the beard area in males, pubic area and lower legs of females, or generally the inner thighs and bottom. An associated itch may or may not be present. Pseudofolliculitis barbae is a type of irritant folliculitis in the beard area.
Pili multigemini hair follicles, also called 'compound hairs', are considered rare although there have been no studies to define the actual frequency in the general population, it is believed to be more common in men's beards and children's scalps.
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