Monilethrix makes hair fiber look like a string of beads. Along the length of a hair fiber there are nodes and constrictions making the edge of the fiber undulate. This hair beading weakens the fiber and people with monilethrix have diffuse hair loss. Most frequently the hair loss is at the back of the scalp and neck and can leave the front of the head relatively unaffected. Monilethrix can also affect hair in other regions of the body. Under a microscope the hair fibers can be seen to have lost their cuticle covering over the nodes while the constrictions keep their cuticle. The brittle hair easily breaks once it is exposed above the skin and the fibers rarely grow very long as a result. Breakage occurs in the weak constriction points along the fiber. Associated with the beaded hairs there can also be defects in the hair follicle itself. The hair follicles may become keratotic and defects develop in the root sheaths. Monilethrix can also be associated with defects in the eyes (cataracts), teeth, and nails all of which are structures with similar properties to hair follicles. Treatment has been attempted with some success. Monilethrix most often occurs in childhood but young adults can also develop it. It can be genetically inherited with an autosomal dominant pattern. Seasonal changes can be observed. It is worse in winter and improves in summer. Monilethrix may spontaneously improve without treatment.

Trichorrhexis invaginata also known as bamboo hair is very distinctive. The hair fibers have the shape of bamboo. Instead of being smooth along their length, the fibers have focal nodules that make the fiber look like bamboo. The nodules are focal defects in the fiber where a cup and ball shape has developed. The hair closest to the scalp forms a bulge with a cup shape form in which the hair fiber further away from the scalp sits. These defects are weak spots in the hair that are easily broken. The piece of hair that sits in the cup shape gets pulled out leaving the exposed socket. This is now called a golf tee hair because of its shape. Bamboo hair is often seen along side other hair fibers the have focal twists in them. These twists, called torsion nodes, create stress on the chemical bonds in the hair and are also weak points where hair fiber is liable to break if pulled. These bamboo hairs and golf tee hairs can occasionally develop in normal hair from over processing but more likely trichorrhexis invaginata is a congenital defect often a symptom of another disease. Netherton’s syndrome is a disease that can involve bamboo hair as well as ichthyosis and atopy. Netherton’s syndrome is usually evident from birth with flaking skin, red rashes and sparse hair growth involving fragile bamboo hair. Netherton’s syndrome is probably the result of an autosomal recessive gene expression. The gene seems to be involved in keratinization of the hair cortex. Examination of hair fibers has shown that the cuticle is normal but the internal cortex is not completely keratinized at sporadic points along its length. These incompletely keratinized areas are soft and weak and the hard, fully keratinized portions of the fiber become impacted into the soft portion creating the cup and socket structure. The improperly keratinized areas of the hair fiber can also become twisted making torsion nodes. Bamboo hair often improves spontaneously as the individual grows. Most treatments involve preventative measures to avoid over processing and physical manipulation. Several treatments are available to remedy skin problems that develop in ichthyosis and Netherton’s syndrome and these may also help improve hair quality.

Bubble hair - as the name suggests, bubble hair is full of bubbles much like a sponge. All hair fibers contain minute air filled spaces called vacuoles. These spaces can also become filled with water when the hair is wet. When people dry their hair using heat they can over do it. Too much heat may make the water in the hair fiber spaces vaporize into steam and steam takes up a larger volume than water. This vaporization of the water may force the spaces in the hair to expand eventually turning the hair into a sponge-like structure. These damaged hairs are weak and brittle as the bubbles destroy the integrity of the fiber. The hair may be kinked, break off, and over time the condition may develop into a localized alopecia. Research articles listed below suggest that hair dryers operating at 175oC or more can cause bubble hair. The use of hair curling tongs operating at 125oC and applied to the hair for one minute can also induce bubbles in hair fiber. Chemical treatment may also precipitate the onset of bubble hair and any already weak hair, whatever the cause, may be more susceptible to bubble development. There is no treatment other than to stop using heat and chemicals on the hair, cut off the old damaged hair, and wait for new hair growth.

Pili annulati - the name refers to hair fiber with rings - sometimes called ringed hair. In pili annulati the hair fiber has alternating light and dark bands along its length like zebra stripes. Usually this hair defect is most obvious in people with blond hair as dark hair obscures the light and dark band pattern. Pili annulati is the result of abnormal keratinization in the hair shaft. The cortex is not a solid structure. It contains spaces or vacuoles between the cells in the center of the cortex. These spaces are filled with air and make excellent minute mirrors to reflect light. Along the length of a hair fiber there are clusters of these spaces at regular intervals that reflect the light while neighboring sections of the fiber with fewer spaces reflect much less light. Consequently the hair looks like it has stripes. The bands can be seen regardless of what direction the source of light is coming from. The hair fiber is overall still very strong although the cuticle can be disrupted and folded. Hair breaking can occur in these fibers across the bands where the hair shaft spaces are present. Pili annulati most frequently develops in children and can be present from birth. Some individuals show a family inheritance pattern that is autosomal dominant. Other cases are isolated and sporadic with no apparent overt genetic component. Pili annulati can sometimes be found in people with alopecia areata or woolly hair. There is no known treatment but the banding pattern is quite appealing.

Pili multigemini - also called compound hair, pili multigemini hair follicles are considered ppretty rare although there have been no studies to define the actual frequency in the general population. The name describes a condition where several separate hair fibers bunch together and emerge from the skin through a single hair channel. The hair looks like a bunch of flower stalks in a vase. There are two separate causes of this diagnosis. First is associated with a regular hair cycling abnormalitiy, such as the older hair at telogen/exogen state does not fall out and remains in hair channel, so as the new hair grows out they bunle together. Another pathology shows that deep in the skin several dermal papilla are closely situated with each of them producing a fiber, but these separate hair follicle bulbs combine together into one hair channel towards the skin surface. Certain type of folliculitis can sometimes be associated with this condition. There is very little information on the treatment of pili multigemini. Plucking the hair seems to be very difficult as the hair fibers are deep rooted and difficult to extract, plus it does not stop the hair growth anyway. Shaving the hair may stop any associated folliculitis and electrolysis has been suggested for permanent hair removal, but no studies have been published to show how effective shaving or electrolysis would be. Cryosurgery has been suggested to remove the follicle(s) entirely.

Pili torti is the common name but the same condition has also been named trichokinesis and corkscrew hair. As the name suggests pili torti is a twisting of hair fiber at focal points along its length. There may be several twists in one hair fiber. The hair cuticle is still intact but the twisting creates stress in the fiber that leads to longitudinal fractures developing in the cuticle and internal hair cortex. The twisting creates a weak point in the hair fiber that can break. Twisted hairs can be found in people with healthy hair and pubic hair is twisted in its normal state. Typically scalp hair is most commonly affected in pili torti but the condition can also be seen in eyebrow and eyelash hair as well as elsewhere on the body in extreme cases. When hair twisting is frequently seen in many scalp hairs, only then is it described as the distinct hair condition pili torti. True congenital pili torti is most frequently found in people with thin blond hair. However, twisting in scalp hair can also occur in a wide range of hair diseases involving fiber defects and brittle hair production. Although most cases of pili torti are congenital in nature, occasionally an individual may develop pili torti later in life. Areas of hair follicles may begin to produce twisted hairs if the follicle are disrupted in some way. Damage to the skin from burns or other forms of scarring may result in damaged hair follicles and production of pili torti hairs. There are no treatments for pili torti but sometimes the condition can improve spontaneously.