White : Diseases of the Skin - Disorders of Hair

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Gary M. White & Neil H. Cox

Diseases of the Skin

28	Disorders of Hair

MISCELLANEOUS DISORDERS OF THE HAIR

Loose anagen syndrome

Etiology and pathogenesis

The root of the hair is abnormal, allowing hair to be removed painlessly by gentle pulling. The typical patient is a child, but occasionally adults may be affected. Autosomal dominant inheritance has been documented.

Clinical

Relatively short, sparse, uneven hair, which may be easily and painlessly removed by gentle pulling, in a child is characteristic. The most commonly affected patient is a girl, less than 8 years old and blonde (Fig.28.49). Patients rarely require a haircut. Onset is in the first years of life. The hair itself is not fragile.

Hair pull easily removes multiple hairs, which on microscopic examination (Fig.28.50) are in anagen. No inner or outer root sheath is seen, and the hair bulb is often distorted, frequently bent at an obtuse angle. The cuticle is often ruffled, resembling a sagging leg warmer. Of note, however, a recent study showed that the hair pull test varies over time with regard to the number of loose anagen hairs that can be extracted. Periods where no hairs could be obtained on hair pull were found. Therefore if loose anagen syndrome is suspected on clinical grounds, then either a hair pluck trichogram or serial reexamination by hair pull would be required to exclude the diagnosis.

Fig. 28.47 Pili annulati. The hair has a regular pattern of darker and paler sections, producing a rippled appearance.

Differential diagnosis

Trichotillomania and other forms of mechanical hair damage may be considered. Short anagen syndrome, by contrast to loose anagen syndrome, causes short hair but not easy ability to pull it out.

Treatment

Currently, no treatment is known to be effective. The family may be reassured that the scalp hair tends to grow longer, denser, and darker in color in adolescence.

Fig. 28.48 Distal trichorrhexis nodosa. Multiple tiny, white ‘beads' are seen on the distal hair. This teenager brushed his hair excessively. Distal trichorrhexis nodosa is quite common and is usually an incidental ?nding.

Fig. 28.49 Loose anagen. The typical patient is a young, blonde-haired girl who rarely, if ever, needs a hair cut.

Fig. 28.50 Loose anagen, hair examination. Pulled hairs are in anagen. No inner or outer root sheath is seen, and the hair bulb is often distorted, frequently bent at an obtuse angle. The cuticle is often ruffled, resembling a sagging leg warmer.

Fig. 28.51 (a,b) Circle hairs. Individual hairs form a perfect circle just below the stratum corneum. (Courtesy of Michael O. Murphy, M.D.)

Circle hairs

The hair grows in a nearly perfect circle just under the stratum corneum. There is no follicular abnormality or inflammatory component. The circles occur scattered among normal hairs (Fig.28.51). It is common on the lower abdomen and waist of overweight older people. Rolled hairs are different and are associated with follicular hyperkeratosis, keratin plugging, and sometimes inflammation. These should not be confused with the ‘corkscrew' hairs of scurvy, which are not retained under the stratum corneum, and which are actually multiply kinked rather than truly of corkscrew morphology.

Trichostasis spinulosa

Trichostasis spinulosa is a common disorder that results from the retention of multiple vellus hairs within the pilosebaceous follicles. The nose is most commonly affected (Fig.28.52), the skin of the face and back possibly being affected as well. Examination from a distance may only reveal black material filling and extending from the pores of the skin. Close-up examination shows multiple tiny hairs emanating from the follicle. Treatment has included use of a depilatory or tretinoin.

Trichomycosis

These yellow concretions on the axillary or pubic hair are usually found incidentally. They represent bacterial colonization by various bacteria, including Corynebacterium tenuis (see Ch 24, Fig. 24.27).

Fig. 28.52 Trichostasis spinulosa. Multiple, black material is seen emanating from individual pores. Close examination shows these to be tufts of hairs.

Pilonidal sinus

This may affect the sacral area or the hands, and rarely other sites such as the breast, and is due to hair entering the skin and tracking through deeper tissues.

The sacral or buttock cleft version is usually an isolated entity, virtually always in men (the invading hair is the patient's own), and sometimes associated with severe acne; treatment, however, is in the province of surgeons, and such cases rarely present to dermatologists for diagnosis.

By contrast, dermatologists may see the version that occurs on hands, termed interdigital pilonidal sinus . It is an occupational disease of hairdressers, in which a painful papule or nodule with a sinus through which hairs may be seen is characteristic (Fig.28.53). The third web space of the hands is most commonly affected. The hair is the customer's (not the patient's) and is consistently thick, stiff, and straight. These hairs will usually work themselves out on their own. Rarely, excision may be needed.

Hair casts

Circles of scale that have originated from the follicular orifice may slide along the hair. It is distinguished from nits, which are stuck to the hair. Various reports have stated they are most common in young girls wearing tight pony tails (Fig.28.54).

Hair color abnormalities

Hair color depends on melanins, and is genetically and racially determined. Progressive graying of hair is common in many races. As discussed earlier, hair color may be affected by diseases such as AA.

Localized hair color difference occurs in the following.

•	Poliosis (white forelock)—a tuft of hair along the frontal hairline may be permanently white. This congenital condition is often inherited and may be unassociated with other defects (Fig.28.55). Rarely, it may be associated with the Waardenburg syndrome (Fig. 28.56) or piebaldism.
•	Alopecia areata—may spare white hairs, or regrowth may be white (see earlier).
•	Inflammatory disorders—for example after herpes zoster.

Diffuse hair color changes occur in the following.

•	Albinism—congenitally pale.
•	Phenylketonuria—hair may be pale..
•	Staining—by cigarette smoke (yellow, frontal), copper (green), anthralin used to treat psoriasis (red-brown), or deliberate color change by use of dyes.
•	Drugs—for example chloroquine and minoxidil.

Fig. 28.53 Interdigital pilonidal sinus. In the course of the hairdresser’s work, a stiff, black hair is driven into the skin.

Fig. 28.54 Hair casts. These white circular scales slide easily along the hair.

Fig. 28.55 A white forelock may occur in the Waardenburg syndrome or piebaldism, or be unassociated with other defects, as in this case.

Fig. 28.56 Waardenburg syndrome. In this autosomal dominantly inherited disorder with variable expression, heterochromia of the irises, white forelock, deafness, broad nasal bridge, lateral displacement of the inner canthi, and depigmented patches occur. (Courtesy of Michael O. Murphy, M.D.)

Scalp dysesthesia

This is not a disorder of hair but is usefully discussed here, especially as it draws attention to the scalp and hair, and may therefore be (erroneously) linked by the patient with hair thinning that was actually already present. The condition is one of itch or discomfort predominantly at the vertex, usually in women, and without any visible abnormality. Although it does not have a dermatomal or individual nerve distribution pattern, a form of neuropathy is suspected; it may respond to topical capsaicin or to agents such as tricyclic antidepressants.