Symptoms, other than hair loss, are often absent and, when present (eg, itching, burning, tingling), are not specific to any cause. Except in alopecia areata (see Hair Disorders: Alopecia Areata), some cases of infection (kerion, syphilis), lichen planus, and dissecting cellulitis of the scalp (folliculitis abscedens et suffodiens), signs of hair loss are nondiagnostic. If scarring is noted, examination should include the entire skin surface and mucous membranes to detect lesions associated with systemic disease.
Male-pattern baldness generally requires no testing. When it occurs in young males without a family history, the physician should question the patient about anabolic steroid use and other drugs. In women with significant hair loss and evidence of virilization, testosterone
and dehydroepiandrosterone sulfate levels should be measured.
The “pull” test helps evaluate diffuse scalp hair loss; gentle traction is exerted on 40 to 60 hairs on at least 3 areas of the scalp, and the number of extracted hairs is counted and examined microscopically. Normally, < 6 telogen-phase hairs should come out. Extraction of > 6 hairs in telogen phase is abnormal and suggestive of telogen effluvium.
The “pluck” test is similar except that hairs are abruptly, painfully extracted. The pluck test helps diagnose a defect of telogen or anagen or an occult systemic disease.
Microscopic examination of hair from either test or from hair cuttings is almost always helpful. Anagen hairs have sheaths attached to their roots; telogen hairs have tiny bulbs without sheaths at their roots. Normally, 85 to 90% of hairs are in the anagen phase; about 10 to 15% are in telogen phase; and < 1% are in catagen phase. Telogen effluvium shows an increased percentage of telogen hairs, whereas anagen effluvium shows a decrease in telogen hairs and easy breakage. A high percentage of hairs in the catagen phase (a transitional phase between growth and rest) and trichomalacia are pathognomonic for trichotillomania. Primary hair shaft abnormalities, such as trichorrhexis invaginata and monilethrix, are usually obvious on microscopic evaluation of the hair shaft.
Scalp biopsy is indicated when alopecia persists and diagnosis is in doubt; biopsy may differentiate scarring from nonscarring forms. Specimens should be taken from an area of active inflammation, ideally at the border of a bald patch. Fungal and bacterial cultures may be useful; immunofluorescence studies may help identify lupus erythematosus, lichen planopilaris, and systemic sclerosis.
Daily hair counts can be performed by the patient to quantify hair loss when the pull test is negative. Scalp hair counts of > 100 are abnormal except after shampooing, when hair counts of up to 250 may be normal. Hairs may be brought in by the patient for microscopic examination of hair shafts and bulbs.Nuestros socios:tamano del pene comprar viagra