Trichorrhexis invaginata (also known as "Bamboo hair" ) is a distinctive hair shaft abnormality that may occur sporadically, either in normal hair or with other hair shaft abnormalities, or regularly as a marker for Netherton's syndrome. The primary defect appears to be abnormal keratinization of the hair shaft in the keratogenous zone, allowing for intussusception of the fully keratinized and hard distal shaft into the incompletely keratinized and soft proximal portion of the shaft.

In 1937, Touraine and Solente first noted the association between hair-shaft defects (bamboo node) and ichthyosiform erythroderma. Còme first coined the term ichthyosis linearis circumflexa in 1949, although Rille had previously recorded the distinctive features of ichthyosis linearis circumflexa by 1922. In 1958, Netherton described a young girl with generalized scaly dermatitis and fragile nodular hair-shaft deformities, which he termed trichorrhexis nodosa. Later, this was more appropriately renamed as trichorrhexis invaginata (bamboo hair) for a ball-and-socket–type hair-shaft deformity at the suggestion of Wilkinson et al.

In 1974, Mevorah et al. established the clinical relationship between ichthyosis linearis circumflexa and Netherton syndrome, and an atopic diathesis was found to occur in approximately 75% of patients with Netherton syndrome.

Bubble hair deformity is an abnormality of the hair shaft.

It is characterized by rows of bubbles seen microscopically within localized areas of brittle hair.

Among the symptoms(and signs) for this condition are the following:

- lack of apparent hair growth

- hair appears patchy

- hair breaks easily close to scalp

- hair may have thickenings or nodes in the shaft

- ends of hair thinned or split

- whitish discoloration of hair tips

- hair breaks easily at tips

Intermittent hair–follicle dystrophy is a disorder of the hair follicle leading to increased fragility of the shaft, with no identifiable biochemical disturbance, also with an unknown prevalence.

Restrictive dermopathy is a rare, lethal autosomal recessive skin condition characterized by syndromic facies, tight skin, sparse or absent eyelashes, and secondary joint changes.

Examination of the hair shafts with a microscope may reveal changes of trichorrhexis nodosa.

Other syndromes with hair abnormalities may also show features of uncombable hair syndrome such as Rapp–Hodgkin ectodermal dysplasia syndrome, loose anagen syndrome, EEC syndrome (ectodermal dysplasia, ectrodactyly and cleft lip/palate) and familial tricho-odonto-onychial ectodermal dysplasia with syndactyly. However, unlike these conditions, uncombable hair syndrome alone is not associated with physical, neurologic, or mental abnormalities.

Uncombable hair syndrome, also known as Pili trianguli et canaliculi, Spun-glass hair, and Cheveux incoiffables, is a rare structural anomaly of the hair with a variable degree of effect. It was first reported in the early 20th century and was described in the 1970s. It becomes apparent from as little as 3 months to up to 12 years of age.

CCCA usually begins at the central (sagittal) midline of the scalp. It is symmetric and exhibits scarring as the name suggests. It involves solely the top of the scalp or may progress to Hamilton–Norwood scale Type VI or VII. Early symptoms may include pruritus, dysesthesias and tenderness. On examination the skin is thin with few follicular ostia and later in the disease the scalp may appear shiny.

Ectodermal dysplasia is characterized by absent sweat glands resulting in dry (hypohydrotic), often scale-like skin, sparse and usually coarse scalp hair that is often blonde, sparse eyebrows and eyelashes, and small brittle nails. In addition, abnormalities of ectodermal derivatives, neuroectodermal derivatives, and mesectodermal derivatives are often found. The ectodermal derivative abnormalities can affect the epidermis including mammary, pituitary and sweat glands, as well as hairs, dental enamel, nails, lens, and the internal ear. Neuroectodermal derivatives that can be affected include sensory placodes, cutaneous pigmental cells, and hair buds. Mesectodermal derivatives affected can include the dermis, hypodermis, dentin, head muscles and conjunctival cells, cervicofacial vascular endothelial cells, and part of the maxillofacial skeleton.

The hypohydrotic symptoms of ectodermal dysplasia described above are evidenced not only in the skin of affected individuals, but also in their phonation and voice production. Because the vocal folds may not be as hydrated as is necessary during the adduction phase of vocal fold vibration (due to lack of lubrication), a complete seal may not be accomplished between the folds and mucosal wave movement may be disrupted. This results in air escapement between the folds and the production of breathy voice, which often accompanies the skin abnormalities of ectodermal dysplasia.

Histopathologic features include a perifollicular lymphocytic infiltrate, concentric lamellar fibrosis (layers of fibroblasts in the papillary dermis), sebaceous gland loss and premature disintegration of the internal root sheath. Additionally, granulomatous inflammation secondary to follicular rupture has been noted. Perifollicular erythema and follicular keratosis is usually absent.

There is much discrepancy in the literature regarding the exact nature of the facial clefting involved in EEC. Some authors claim that the clefting involved in EEC is always cleft lip +/- palate and use this marker as a means of distinguishing EEC from other syndromes, such as AEC syndrome (ankyloblepharon, ectodermal dysplasia, and clefting) in which other types of clefting are found. Other authors include cleft palate only (CPO) in conjunction with ectrodactyly and ectodermal dysplasia as sufficient for a diagnosis of EEC.

Netherton syndrome is characterized by chronic skin inflammation, universal pruritus (itch), severe dehydration, and stunted growth. Patients with this disorder tend to have a hair shaft defect (trichorrhexis invaginata), also known as "bamboo hair". The disrupted skin barrier function in affected individuals also presents a high susceptibility to infection and allergy, leading to the development of scaly, reddish skin similar to atopic dermatitis. In severe cases, these atopic manifestations persist throughout the individual's life, and consequently post-natal mortality rates are high. In less severe cases, this develops into the milder ichthyosis linearis circumflexa.

Netherton syndrome has recently been characterised as a primary immunodeficiency, which straddles the innate and acquired immune system, much as does Wiskott-Aldrich syndrome. A group of Netherton patients have been demonstrated to have altered immunoglobulin levels (typically high IgE and low to normal IgG) and immature natural killer cells. These Natural Killer cells have a reduced lytic function; which can be improved with regular infusions of immunoglobulin (see 'Treatment'); although the mechanism for this is not clear.

Patients are more prone than healthy people to infections of all types, especially recurrent skin infections with staphylococcus. They may have more severe infections; but are not as vulnerable to opportunistic pathogens as patients with true Natural Killer cell deficiency-type SCID.

Restrictive dermopathy (RD) is caused either by the loss of the gene ZMPSTE24, which encodes a protein responsible for the cleavage of farnesylated prelamin A into mature non-farnesylated lamin, or by a mutation in the LMNA gene. This results in the accumulation of farnesyl-prelamin A at the nuclear membrane. Mechanistically, restrictive dermopathy is somewhat similar to Hutchinson–Gilford progeria syndrome (HGPS), a disease where the last step in lamin processing is hindered by a mutation that causes the loss of the ZMPSTE24 cleavage site in the lamin A gene.

Sebaceous glands are normal structures of the skin but may also be found ectopically in the mouth, where they are referred to as "oral Fordyce granules" or ectopic sebaceous glands.

On the foreskin they are called Tyson's glands, not to be confused with hirsuties coronae glandis.

When they appear on the penis, they are also called "penile sebaceous glands".

When seen as a streak of individual glands along the interface between the skin of the lip and the vermilion border, the terms Fox–Fordyce disease and Fordyce's condition have been used.

On the shaft of the penis, Fordyce spots are more visible when the skin is stretched, and may only be noticeable during an erection.

The spots can also appear on the skin of the scrotum.

Oral Fordyce granules appear as rice-like granules, white or yellow-white in color. They are painless papules (small bumps), about 1–3 mm in greatest dimension. The most common site is along the line between the vermilion border and the oral mucosa of the upper lip, or on the buccal mucosa (inside the cheeks) in the commissural region, often bilaterally. They may also occur on the mandibular retromolar pad and tonsillar areas, but any oral surface may be involved. There is no surrounding mucosal change. Some patients will have hundreds of granules while most have only one or two.

Occasionally, several adjacent glands will coalesce into a larger cauliflower-like cluster similar to sebaceous hyperplasia of the skin. In such an instance, it may be difficult to determine whether or not to diagnose the lesion as sebaceous hyperplasia or sebaceous adenoma. The distinction may be moot because both entities have the same treatment, although the adenoma has a greater growth potential. Sebaceous carcinoma of the oral cavity has been reported, presumably arising from Fordyce granules or hyperplastic foci of sebaceous glands.

In some persons with Fordyce spots, the glands express a thick, chalky discharge when squeezed.

The management of hair loss, also known as alopecia or baldness, may include medications and surgery.

Clinical expressions of PPS are highly variable, but include the following:

- Limb findings: an extensive web running from behind the knee down to the heel (90%), malformed toenails, and webbed toes.

- Facial findings: cleft palate with or without cleft lip (75%), pits in the lower lip (40%), and fibrous bands in the mouth known as syngnathia (25%).

- Genital findings (50%): hypoplasia of the labia majora, malformation of the scrotum, and cryptorchidism.

Netherton syndrome is a severe, autosomal recessive form of ichthyosis associated with mutations in the "SPINK5" gene. It is named after Earl W. Netherton (1910–1985), an American dermatologist who discovered it in 1958.

Signs and symptoms include:

- syndromic facies

- hearing loss

- facial paralysis

Pseudofolliculitis barbae (PFB), also known as barber's itch, folliculitis barbae traumatica, razor bumps, scarring pseudofolliculitis of the beard, and shave bumps, is a medical term for persistent irritation caused by shaving. Pseudofolliculitis barbae was first described in 1956.

Keratosis pilaris results in small bumps on the skin that feel like rough sandpaper. They are skin-colored bumps the size of a grain of sand, many of which are surrounded by a slight pink color in light skinned people and dark spots in dark skinned people. Most people with keratosis pilaris do not have symptoms but the bumps in the skin can occasionally be itchy.

Though people with keratosis pilaris experience the condition year-round, the problem can become exacerbated and the bumps are likely to look and feel more pronounced in color and texture during the colder months when moisture levels in the air are lower. The symptoms may also worsen during pregnancy or after childbirth.

Acanthosis nigricans may present with thickened, velvety, relatively darker areas of skin on the neck, armpit and in skin folds.

Tricho-hepato-enteric syndrome is one particular form of intractable diarrhea of infancy, presenting typically in the first month of life. These babies were usually born small for their age and continue to experience failure to thrive, usually with a final short stature. Typical facial features include prominent forehead and cheeks, a broad nasal root and widely spaced eyes (hypertelorism). Their hairs are woolly, easily removed and poorly pigmented. Liver disease is mainly present as cirrhosis or fibrosis, and staining might reveal high iron content of the liver cells (consistent with hemochromatosis). Most evaluated patients had some degree of decrease in intelligence.