Lactology Foundation

Alopecia

Hair loss has a psychological impact out of all proportion to its physical significance, but disorders causing hair fall may also sometimes be a marker for systemic disorders. Convenient clinical division of the possible causes of alopecia can be made
by considering: (i) whether or not obvious scalp skin abnormality is present; and (ii) the distribution of hair loss, for example localized, generalized or male-patterned.

PATCHY HAIR-THINNING/BALDING ACCOMPANIED BY OBVIOUS SCALP SKIN DISEASE
Hair loss is surprisingly uncommon in eczema and psoriasis of the scalp, even when they are severe.
Allergic contact sensitivity to hair dye is a common cause of a severe eczematous eruption of the scalp, face and neck, but hair loss is rarely a major feature. Small infants with a severe generalized atopic eczema may produce a patch of alopecia at the occiput through habitual rubbing of the head on the pillow.

A child presenting with one or more localized bald areas on the scalp associated with broken stubbly hairs and scaling of the affected area of the scalp is always suggestive of tinea capitis (scalp ringworm) (see SCALP AND BEARD, FUNGUS AFFECTIONS OF). The degree of surrounding inflammation and scaling is very variable, and depends on the fungus responsible, and the host response. Cattle ringworm (Trichophyton verrucosum) may produce a particularly violent reaction, with swelling, discharge and local lymphadenopathy, a condition termed a 'kerion'; direct microscopy of plucked hairs and subsequent culture on Sabouraud's medium will confirm the diagnosis.
Bacterial folliculitis, if extensive enough, sometimes perpetuated by infestation with head lice, can cause patchy hair loss, sometimes with scarring developing in late or neglected cases. Pustules should be easily found, and there will be draining lymphadenopathy. A sterile inflammatory folliculitis (folliculitis decalvans) is a rare cause of patchy balding in those who are middle-aged.

Scarring alopecia
Various inflammatory conditions of the scalp can result in destruction of hair follicles by a scarring process; in such cases, hair loss is inevitably irreversible in the affected areas. Examination of the surface of the scalp with a hand lens reveals loss of follicles, and sometimes several hairs emerging together from a single orifice. Discoid lupus erythematosus and lichen planus are common causes of scarring alopecia. More esoteric causes include sarcoidosis, radiotherapy, lupus vulgaris and pseudo-pelade. If the scarring is linear, especially if it extends to the forehead and has a violaceous edge, localized scleroderma (morphoea) may be the cause. The entire lesion has the appearance of an exaggerated scar – en coup de sabre.

Lichen planus with scarring alopecia (Graham-Little syndrome).

Alopecia secondary to radiation.

PATCHY HAIR-THINNING/BALDING WITH NORMAL UNDERLYING SCALP SKIN
Alopecia areata is the most common cause of patchy baldness. Patches are asymptomatic and are often discovered by relatives or hairdressers. Patients of any age are affected, especially those in late childhood or early teens. The hallmark of this disease is a neat, sharply localized patch of billiard-ball baldness with no obvious inflammation or scaling at the edge of lesions, and the diagnostic exclamation mark hairs should be searched for. There are usually two or three patches, and sometimes these coalesce at an alarming rate and may even cause alopecia totalis of the scalp, or alopecia universalis in which beard and all body hair are lost. The course and prognosis are highly variable but generally good. On average, two or three patches appear, remain stable for anything up to 6 months, and then regrow without trace within 12 months. The regrowing hairs are initially often white. The cause is unknown, although there is a family history in 30 percent of cases, and it is occasionally associated with autoimmune diseases such as vitiligo, thyroid disease, pernicious anemia or Addison's disease. A convincing preceding history of emotional shock is given by a proportion of patients, and may be a triggering factor.

Alopecia areata - above

Syphilis, although relatively uncommon, is a diagnosis that must not be overlooked. Patchy alopecia may be a feature of the secondary phase. The appearance is of an asymptomatic patchy 'moth-eaten' baldness.
On examination, there is no scaling or obvious scalp disease and, in contrast to alopecia areata, baldness is partial rather than complete. Exclamation mark hairs are not seen, and the patches are more numerous and accompanied by fever, sore throat and
lymphadenopathy. The serology is positive, and the hair regrows after antibiotic treatment.
Trichotillomania is the rather cumbersome title given to what often amounts to only a 'habit tic'. If hair is twirled between the fingers, it eventually breaks, leaving patches of shortened hair. Microscopic examination reveals obvious fractured ends of the affected hair.
Some psychiatrically disturbed individuals pursue hair pulling and produce bald patches. The fractures may be seen at the scalp surface, or even at the roots.
Traction alopecia is seen at the hair margins and is due to regular hairdressing techniques, for example rollers, braiding, ethnic plaiting and tight pony tails, pulling on the hairs.

Traction alopecia - above.

DIFFUSE ALOPECIA WITHOUT SCALP DISEASE
Telogen effluvium
A growing (anagen) hair has a large bulb, easily seen with a hand lens on plucking. When growth stops, the bulb shrinks, and the hair enters a resting (telogen) phase for 3 months before falling (catagen). In healthy adults, some 50–100 hairs enter telogen daily, and thus fall some 3 months later. Not surprisingly, certainly
events upset the hair cycle, whereupon a larger number of hairs stop growing and enter telogen.
Three months later, they will fall as a so-called 'telogen effluvium'.
Triggering events include childbirth, stopping the contraceptive pill, a febrile illness, blood loss, an operation, myocardial infarction, stroke, rapid weight loss, bereavement or other psychological stress.
The patient often complains of a worrying increase in hair fall, but on examining the scalp, no obvious abnormality is seen although, if the hair is gently grasped between thumb and finger, many telogen hairs may be detached. Further evidence can be obtained
by asking patients to collect their daily hair fall from hair brushes and pillows. Normally, some 50–100 hairs can be collected, and 300–400 can fall daily in telogen effluvium. The prognosis is excellent.

Alopecia universalis - above.

Anagen effluvium
Fall of growing hairs also causes diffuse hair-shedding, and may occur after exposure to certain drugs or poisons, for example cytotoxics, isotretinoin, thiouracil, anticoagulants, excess vitamin A and thallium poisoning.
Diffuse hair fall occurs in endocrinopathy, for example myxoedema, hypopituitarism and hypoparathyroidism. Myxoedema is regularly accompanied by hair thinning. The mechanism is unknown and may not be directly related to serum thyroxine level, as adequate replacement therapy may fail to reverse the process. Hair loss may be a feature of systemic lupus, and it may even be the presenting symptom.

Male-pattern baldness without obvious scalp disease
Male-pattern baldness is not a disease, but an accelerated physiological process, especially pronounced in those with a genetic predisposition.
Males and females progressively lose androgen dependent scalp hairs with increasing age – in males with successive thinning of the bitemporal, occipital and pate areas, and in females with a more diffuse patterned thinning over most of the vertex. Some
individuals have increased sensitivity of their hair follicles to normal levels of circulating androgens, and lose their androgen-dependent hair earlier. Such hair fall does not occur in those who have been castrated, and oestrogens and anti-androgenic drugs appear to have a protective effect. The prognosis for regrowth is
poor, although many individuals search in vain for a cure.