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Scalp Pathology for the Hair Transplant Surgeon: Hair Loss Diagnosis Bernard Nusbaum, M.D. Reprinted from Hair Transplant Forum International: If one performs enough hair transplant consultations, patients with alopecias of different etiologies will be encountered. The primary requirement in that first visit is to make a correct diagnosis. This is accomplished by taking a directed history, performing a scalp examination using specific clinical assessments and, in selected cases, performing microscopic analysis of hair and/or scalp biopsy. A complete description of the different alopecias is beyond the scope of this article. A logical approach to narrowing a differential diagnosis and a description of some of the clinical diagnostic tools employed in this process will be presented. The HistoryIn obtaining a history, effort should be made to differentiate between: 1) Hair Loss vs. Hair Breakage and 2) Thinning vs. Shedding. Hair Breakage would be typical of chemical damage, trichotillomania, hair shaft anomalies (which are rare) or anagen effluvium (secondary to chemotherapy or toxin exposure). Hair Loss, if diffuse, should direct the history toward differentiating thinning vs. shedding. Thinning would be typical of androgenetic alopecia (AGA) or Female Pattern Hair Loss (FPHL) whereas shedding would be a characteristic of Telogen Effluvium. In the setting of diffuse hair loss one should inquire about possible precipitating factors, such as chronic illness, hormonal change, recent surgery or medications, among other factors (Tables I & II). Also, the time frame from the precipitating factor to the onset of hair loss is important. Telogen effluvium typically occurs approximately 3 months from the time of the precipitating event whereas anagen effluvium results in hair breakage beginning 2-6 weeks after exposure to the toxin. The work-up of women with diffuse alopecia of undetermined origin should include blood work consisting of CBC, thyroid profile, iron, ferritin and ANA. If symptoms or signs of androgen excess are present, testosterone, DHEAS and prolactin levels should be ordered. Scalp ExaminationThe scalp examination begins by looking for a recognizable pattern. Interestingly, this approach was utilized in what is, to the author's knowledge, the first reference to hair loss diagnosis (Fig. 1). The Old Testament, in Leviticus, Chapter 13, refers to recognition of leprosy for the purpose of quarantine. Even in those ancient times, pattern baldness was recognized by its typical frontal and crown alopecia. Generally recognizable patterns are seen in male or female pattern alopecia, traction alopecia, triangular alopecia, post-face-lift alopecia, etc. If these patterns are not recognized a more thorough history and physical examination need to be performed. It should be noted that alopecias can mimic each other; examples are diffuse Alopecia Areata and Fibrosing Alopecia in a Pattern Distribution, both which initially suggest a diagnosis of AGA/FPHL. Continuing with the physical examination, essential determinations are whether the hair loss is diffuse or focal; scarring or non-scarring. The typical clinical appearance of scarring alopecia consists of areas a few millimeters in diameter which can coalesce to form larger patches in which hair loss occurs. In areas of active disease (which typically are at the periphery of the alopecic areas) there is evidence of inflammation with perifollicular erythema and scaling. The inflammatory process results in permanent destruction of the hair follicle with obliteration of the upper follicular duct so that the affected scalp appears smooth, shiny and devoid of pores (Fig 2-4). Scarring alopecias are listed in Table III. Each has distinctive clinical, histopathologic and inmunohistologic features and generally, biopsy is required for diagnostic confirmation and determination of disease activity. Ancillary ToolsWhen it is not obvious whether the alopecia is diffuse or focal, one of the tools utilized is a part width assessment (fig 5). This is performed by making a series of parallel parts one at a time and comparing the part width in different areas. If there is decreased part width throughout, the thinning is diffuse; if the part width is decreased in a localized area, then the alopecia is focal. Diffuse, non-scarring alopecia would be seen in telogen effluvium, diffuse alopecia areata and the loose anagen syndrome. A list of non-scarring focal alopecias is presented in Table IV. These can be differentiated by unique clinical or laboratory features. Some also have a distinctive histopathology. An important tool to assess diffuse hair loss is the Hair Pull Test. This test is performed by gently pulling 50-100 hairs proximally to distally. This is repeated two to three times in different areas and no more than 5 telogen hairs obtained is normal. The hair pull test can confirm that abnormal hair shedding is actually occurring and results can vary depending when the hair was last shampooed and combed. In AGA/FPA the hair pull test may be normal or elevated. If elevated it will be so in "androgen dependent" areas and normal in "non-androgen dependent areas". In AGA/FPA the proximal portion of the pulled hairs show that they have the typical "club" structure of telogen hairs. In telogen effluvium, the hair pull would be abnormal all over the scalp and to a greater dgree than in AGA/FPA. In anagen effluvium the hair pull would again be abnormal throughout but one would see dystrophic anagen hairs characterized by tapered, broken proximal ends. In alopecia areata, inflammation develops around the anagen follicles and causes anagen arrest. The dystrophic anagen hairs obtained on a hair pull in anagen effluvium and alopecia areata show a tapered, broken tip of the proximal shaft. The hair pull test can also be used to follow the course of telogen effluvium. Another way to confirm abnormal hair shedding is a Daily Hair Collection. The patient is asked to collect all hairs shed daily for 7 days. Each daily collection is placed in an individual plastic bag and brought in to the office. An average daily loss is calculated and up to 100 hairs per day is considered normal. Although this test is difficult for patients to perform, it can clarify the results of a borderline hair pull test, assist in following the course of telogen effluvium or help reassure a patient when results are normal. The Hair Feathering Test is used to detect fragile ends which usually result from chemical damage to the shafts from coloring, straightening or permanents. Fragility can also be seen secondary to hair shaft anomalies, which are less common. The technique involves tightly grabbing the distal 2-3 centimeters of hairs between the thumb and forefinger and repeatedly pulling proximally to distally in different areas. Obtaining short hair fragments on the fingers constitutes an abnormal, positive test. A Hair Window is utilized to evaluate patients who claim their hair doesn't grow (usually a feature of patients with trichotillomania). A one-inch square area is clipped or shaved on a site of the head which is difficult for the patient to reach. The site can also he covered with an occlusive dressing. Hair growth is then observed over days to weeks. Normal hair growth rate is 0.4 mm. per day. Microscopic Examination of HairsWhen the proximal ends of hairs obtained on a hair pull test are viewed under the microscope at 10x power, one will see either telogen bulbs, abnormal anagen hairs or broken hairs.
The hair shaft anomalies are listed in table V. Their description can be reviewed in appropriate texts and articles referenced below. Microscopic examination can also be used to determine hair shaft diameter (caliber) and to differentiate miniaturized vs. normal size terminal hair shafts. In cases where one wants to determine to determine an anagen : telogen ratio a hair pluck test can be performed. In this test hairs are grasped using a hemostat with rubber-coated tips and 15-20 hairs are extracted with a quick pull. A total of 50 hairs are extracted and the proximal ends are examined under light microscopy. Scalp biopsy is indicated in: suspected scarring alopecia, questionable alopecia areata, questionable trichotillomania and any case of unexplained diffuse hair loss. At least two specimens should be obtained; one for vertical and one for horizontal sections. Some dermatopathologists suggest that an additional third specimen from normal (uninvolved) scalp should be submitted. The specimens should be 4-6 mm in diameter and include the subcutaneous tissue. The biopsy site is important. In cases of suspected scarring alopecia, biopsy the periphery of the alopecic area or wherever erythema and/or scaling is present. In alopecia areata, biopsy the area of most recent hair loss. The importance of submitting the specimen to a dermatopathologist with expertise in scalp pathology cannot be over stated. Despite the perceived difficulty of evaluating hair loss patients, the physician should adhere to a systematic approach of obtaining a relevant history and performing a thorough scalp examination to formulate a differential diagnosis. When indicated, the diagnostic tools presented should aid in narrowing the differential diagnosis until the correct diagnosis is made. Only then, can an appropriate treatment plan be instituted. Table I
Table II
Table III
Table IV Focal, Non-scarring Alopecias
Table V
Fig 1 If the hair of a man's head falls out, he is bald at the back of his head, he is pure. And if his hair falls out toward the front of his head, he is frontally bald, he is pure. And if in the baldness there shall be a white affliction streaked with red… he is contaminated.Old Testament - Leviticus, Chapter 13 Fig 2 
Fig 3 
Fig 4 
Fig 5a 
Fig 5b 
Legends to Figures
Fig 1: In Biblical times, male common baldness was differentiated from leprosy by its frontal and crown hair loss pattern. Fig 2: Typical appearance of Lichen Planopilaris Fig 3: Pseudopelade. This entity may represent the end-stage of other primary scarring alopecias. Fig 4: Extensive Scarring Alopecia Fig 5: Part Width Assessment
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