Focal Hair Loss
For a list of focal hair loss conditions see Box 4 .
Occipital neonatal alopecia (transient neonatal hair loss) is a common alopecia that develops in the occipital area in the first few months of life. It was previously wrongly attributed to friction of the head on the pillow but it is actually explained by an understanding of hair cycle patterns during the intrauterine life. The fetus normally undergoes synchronous shedding of scalp hair in the fifth month of fetal life. The regrown hair enters into the telogen phase in a wave from front to back, starting approximately 12 weeks before term. Most hair roots will have entered the anagen phase again before delivery. The occipital area is the last area in the scalp to enter the telogen phase and does not do so until birth. Therefore, shedding of hair in the first weeks of life is normal and the pillow, which is often blamed, only aids this shedding. Parents should be informed that there is no relationship between the sleep position and the onset of this problem. Neonatal occipital alopecia regresses spontaneously.[24]
Temporal triangular alopecia is a not rare condition and is noted at 2-5 years of age as a well-circumscribed triangular or oval patch of alopecia that involves the temporal region. It is unilateral in most cases. Vellus, thin hair is present in the affected area.
The condition is often mistaken for AA. However, histologic examination is not always necessary, because of the typical location and shape of this form of alopecia, the presence of vellus hair and the absence of exclamation point (dystrophic) hair. Temporal triangular alopecia is benign but there is no effective treatment.[25]
A rare syndrome associated with temporal alopecia is Setleis syndrome. It is inherited by the autosomal dominant trait and is characterized by cutis aplasia or atrophic skin at the temples, which is said to resemble forceps marks. There may also be a coarse facial appearance, anomalies of the eyelashes and eyebrows, and periorbital puffiness.[26]
Aplasia cutis congenita is a rare condition, affecting newborns. There is a patch of hair loss, usually occurring on the scalp, characterized by atrophic skin. Sometimes, in the affected area, vesicles or ulcers develop. Lesions range from a few millimeters to many centimeters in diameter. Differential diagnosis includes nevus sebaceous, obstetric trauma and epidermolysis bullosa.
Aplasia cutis congenital has no clear cause and it can be associated with other developmental anomalies. Treatment is rarely necessary and prognosis is usually good.[27]
Nevus sebaceous of Jadassohn is a common, solitary, benign congenital lesion that typically presents at birth or within the first few months of life. Most cases are sporadic, although rare familial cases have been reported. The pathogenesis is unknown and it represents a hamartoma.
Before puberty, nevus sebaceous appears as an oval or linear, well-circumscribed hairless plaque of yellowish or orange papules on the scalp or face. Less-common sites include the neck, trunk and extremities. After puberty, the lesion tends to be yellow-brown to brown and verrucous.
Although nevus sebaceous, in most cases, is solitary, very rarely multiple plaques have been documented. Likewise, extensive lesions are rarely associated with multiple internal abnormalities (ocular, skeletal or CNS), similar to those reported in the linear epidermal nevus syndrome.
Histologically, early skin lesions reveal immature sebaceous glands with incompletely formed hair follicles. In older lesions, papillomatous epithelia hyperplasia with hyperkeratosis, enlarged sebaceous glands and appocrine glands are observed. In well-developed lesions, clinical diagnosis appears to be easy. Differential diagnosis includes AA, congenital aplasia cutis, warts and, in older people, basal cell carcinomas or adnexal neoplasms.
Nevus sebaceous is generally a benign organoid nevus. Although in the past it was considered that basal cell carcinoma could arise on sebaceous nevi commonly (15-20% of cases), two recent retrospective studies indicate that this incidence is quite low (0-1.7%). Development of squamous cell carcinoma or apocrine carcinoma is rare.[28,29]
Prophylactic excision of a nevus sebaceous is controversial. Some investigators suggest surgical excision before puberty, because of the malignant potential and cosmetic considerations. Some others suggest that prophylactic excision is not recommended.[28]
Traction alopecia is caused by prolonged traction of scalp hair by tight braids, 'pony tails' and rollers, for example. The disease presence is associated with hairstyles and there is a cumulative effect when traction is applied to chemically relaxed (straightened by sodium and guanidine hydroxide) hair. Traction alopeciaprevalence has been reported to be higher with traction from artificial extensions compared with that from natural long hair.[30] Although this condition is normally reversible, if the traction is continued over months to years, a chronic severe mechanical damage to hair follicles may result in permanent hair loss.
Alopecia areata is a localized loss of hair in circumscribed areas without any visible inflammatory signs. Almost all patients exhibit hair loss on the scalp, body and even eyelashes and eyebrows. The disease onset in approximately 60% of patients is before the age of 18 years and affects both sexes equally. Approximately 1.7% of the population will experience an episode of AA during their lifetime.[31,32]
With the exception of androgenetic alopecia, AA is the most frequently occurring form of hair loss. AA is a chronic, organ-specific autoimmune disease, probably mediated by autoreactive T cells, which affects hair follicles and, sometimes, nails. The exact cause is unknown. Genetic factors play an important role in the etiology of AA and the genetic predisposition is polygenic in nature. There is a strong association with the genes of the HLA-D region.[33] A total of 10-42% of patients give a family history of the disease.[34]
There have also been reported associations between AA and classic autoimmune disorders, such as thyroiditis Hashimoto, vitiligo and/or autoimmune polyglandular syndrome-1. AA is also common in Down's syndrome.
A variety of environmental factors, physical or psychological, have been suggested as 'trigger factors', but most patients with AA are unaware of any precipitating factor with the exception of emotional stress. Nevertheless, there are studies revealing that stress does not play any role in the pathogenesis of AA.[35] AA manifests with several different features. Typically, patients present with a circumscribed area that is completely devoid of hair. The lesions are round or oval, bald, smooth and may be singular or multiple. The affected area is characterized in many cases by the intact hair and the pathognomonic 'exclamation-mark' hair. The intact hair is dystrophic anagen or telogen hair, the distal segment of which is broader than the proximal end.
Whenever a pull test at the margins of the lesion is positive, the disease is very active. Clinical presentation of AA is subcategorized according to pattern as:
Patchy AA, the most common form
Ophiasis, when the bald-like hair loss is located in temporo-occipital scalp
Diffused AA, when an intense decrease in hair is observed over the entire scalp
In addition, AA is subcategorized according to the extent of hair loss as alopecia totalis (AT), meaning 100% loss of scalp hair, and alopecia universalis (AU), meaning the total loss of all terminal hair on scalp and body. In both cases, regrowth in one site and extension on another site may be seen at the same time in a single patient.
Nail dystrophy often occurs with AA, especially in children and in AT and AU sufferers. Fine pitting, red spotted lunula, trachyonychia, punctuate or transverse leukonychia or onychomadesis may be associated with AA.
Clinical diagnosis of AA is usually easy. Dermoscopy is a new method that seems to improve the diagnostic capability beyond simple clinical inspection.[36] Differential diagnosis includes tinea capitis, trichotillomania, triangular temporal alopecia, scarring alopecia (e.g., trauma), telogen effluvium or circumscribed alopecia (e.g., nevus sebaceous and aplasia cutis congenita).[37]
Spontaneous remission is common in the majority of cases in patchy alopecia, although most patients experience recurrences. Poor prognosis indicators are a young age of onset (especially before puberty), a positive family history, extensive hair loss (ophiasis, AT and AU), atopy, the presence of other immune disorders and nail involvement.[37]
In children with the usual type of AA (1-3 small patches) prognosis is fairly good and their hair is expected to regrow entirely within 1 year, even without treatment. However, approximately 30% of young patients will have a future episode of AA and 7-10% will have a severe chronic form of the disease.[34,37]
There is no effective or specific treatment for AA. At present, all treatments are palliative and do not cure the disease.[38] Many forms of local, systemic and combination therapies have been proposed. Unfortunately, even though they slightly help some of the patients, they do not alter the long-term course of AA. Topical, intralesional and systemic steroids, anthralin minoxidil, psoralen and UVA treatment (photochemotherapy), ciclosporin and topical immunotherapy are the main treatment modalities. Topical immunomodulators have also been used, although their efficacy is controversial.[39]
Although there are no evidence-based studies regarding the first- and second-line treatments in AA in childhood, there is a generally accepted therapeutic algorithm with a treatment plan based on the patient's age and the extent and duration of alopecia. In children younger than 10 years, mild-potency topical corticosteroid alone or in combination with minoxidil or topical anthralin and oral zinc are good therapeutic options.[37,40]
For patients older than 10 years of age and with less than 50% scalp hair loss, intralesional corticosteroids are added to the proposed options. In this age group, when there is more than 50% involvement, topical immunotherapy with contact sensitizers (diphenylcyclopropenone and squaric acid dibutyl ester [SADBE]) is the most effective therapeutic modality, although several studies have demonstrated efficacy and safety in children younger than 5 years of age.[37,41,42] In severe AA, topical SADBE represents a valid therapeutic option, and may be disease modifying, reducing the relapse rate and severity.[43]
The risks and benefits of all available treatments should be explained. Psychological support plays a crucial role in the overall therapeutic strategy for both children and their parents. It is also of great importance to emphasize the probability of a spontaneous remission.
Trichotillomania is currently classified as a compulsive disorder that commonly affects children, especially girls. The prevalence rate is between 0.5 and 3% of the population under 18 years of age.[44,45]
Trichotillomania affects mainly the scalp. However, other terminal hairs can be involved, especially eyelashes and eyebrows. It is usually localized but sometimes widespread areas of alopecia are also seen, due to plugging of hair that characteristically contain hair of varying length. This clinical feature is most probable due to the common technique of twisting multiple strands around fingers and pulling them simultaneously. Sometimes, skin of the involved area shows folliculitis and repeated trauma may result in small scarring. The uninvolved areas appear completely normal.
Differential diagnosis includes other conditions of nonscarring alopecia (e.g., AA). Shaving of a small area in the involved part of the scalp ('hair window test') and watching the normal regrowth of hair in this area, confirms the diagnosis of trichotillomania.
Typical histopathologic findings include pigment casts, catagen hair, deformed hair shafts (trichomalacia), perifollicular hemorrhage (in early lesions) and traumatized hair bulbs without significant inflammation or scarring.
Since children with trichotillomania do not admit their habit, their parents may be reluctant to accept the diagnosis.
Effective treatment of this obsessive-compulsive disorder is difficult. Self-monitoring, teaching patients to do something else whenever they feel the need to twist and pull their hair and, in severe cases, psychotherapy with antipsychotic agents (e.g., selective serotonin reuptake inhibitors or clomipramine 100-200 mg/day) have been reported to be effective. Hypnotherapy may also be useful, particularly in children.[46]
Trichotillomania, especially in adults, is a chronic disorder and is often associated with trichophagy, possibly leading to intestinal obstruction from trichobezoars. Comorbid psychiatric disorders are anxiety and depression.
Expert Rev Dermatol. 2008;3(6):677-690. © 2008 Expert Reviews Ltd.
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