• Diagnosis of alopecia areata
• Diagnosis of alopecia areata references

Diagnosis of alopecia areata

Alopecia areata is a non-scarring, inflammatory, hair loss disease that is seen in men, women and children. This condition is commonly manifested by patchy areas of complete hair loss on the scalp and other body parts. In severe cases, alopecia areata can progress to complete loss of all body hair. While not a life threatening condition, alopecia areata nonetheless has serious implications for the victim and family members because of its psychological and sociological backlash.

Although great progress has been made in the research of hair diseases, the exact etiology of alopecia areata is still to be established. However, there is a lot of evidence to support the fact that alopecia areata is a multi-entity disorder with causes that are multifactorial, including evident autoimmune and genetic components. The disease presents with the loss of scalp and body hair by interruption of their synthesis. There is no destruction or atrophy of the follicles, and therefore the hair loss can be reversible.

Normally, hair growth in each hair follicle occurs in a cycle. There are three main phases of the hair growth cycle anagen (active growth phase), catagen (period of controlled regression) and telogen (resting state in the hair follicle cycle). Alopecia areata primarily affects the hair follicle as it enters the anagen phase, and studies further indicate that the initial event in the development of alopecia areata is the premature precipitation of anagen follicles into the telogen state or resting state of the hair follicle cycle.

There is currently no conclusive diagnostic test for alopecia areata Dermatologists deduce alopecia areata by a process of elimination of other hair loss causes and close examination of the lesion itself. Typically, the initial alopecia areata lesion appears as a smooth bald patch sometimes within 24 hours. Some people feel a tingling sensation or pain in the affected area. The scalp is the most commonly affected area but alopecia areata can present in any region of hair on the body. Hair pull tests are sometimes conducted at the margins of lesions. If hair is easily pulled out, it is indicative that the lesion is active and further hair loss should be anticipated.

The hair fiber that falls out in alopecia areata has been the subject of several analytical studies and is sometimes used to diagnose alopecia areata. Using scanning electron microscopy the hair fibers falling out from the edge of an expanding bald patch can look very unusual. Frequently, the part of the hair fiber furthest away from the scalp (the oldest part of the hair) looks normal. Closer to the scalp (newer part of the hair) and it can look quite aberrant. We find the shape of the fiber becomes increasingly irregular the closer to the scalp we look. This involves deposits of unordered keratin and constrictions in the hair fiber. The cuticle can be missing and there can be longitudinal cracks along the length of the hair. Analysis of the hair fiber shows the constituent keratins to remain the same but the way they are assembled to make up the fiber becomes increasingly abnormal.

The irregular construction of the hair gives it weak spots where it can readily break off. This gives rise to the stumpy hair fibers called exclamation mark hairs that can often be seen in expanding patches of alopecia areata. The hairs are so called because they look like an exclamation mark [!]. Some dermatologists use presence of exclamation mark hairs as diagnostic for alopecia areata. However, it has been shown that exclamation mark hairs can occasionally occur in other conditions as well.

Anywhere between 7% and 66% of people with alopecia areata also have aberrant nail formation depending on which reports you read (Muller 1963, Baran 1984). It is generally agreed that 25% is a more realistic figure (around the mid point between 7% and 66%). Disruption of growth may involve all or just one of the nails. Nail dystrophy varies from a diffuse, fine pitting to severe alteration in a few cases (Gollinck 1990).

For a more definitive diagnosis, dermatologists sometimes need to take a small skin biopsy (a small piece of skin about 4mm in diameter) for microscopic examination. With this, dermatologists can see whether there is focal inflammation of the hair follicles. This is the clearest method of identifying alopecia areata. More recently it has been suggested that a blood samples could be tested for the presence of hair follicle specific autoantibodies. However, while this is possible to do in a research or pathology laboratory no standardized test has been developed for the general dermatology clinic.

Diagnosis of alopecia areata references

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