A Cross Sectional Study Of Dermoscopic Findings In Non-Cicatricial Alopecia

Abstract

Background: Hair loss can be cicatricial or scarring and non-cicatricial or non-scarring based on the damage to the hair follicle. The primary conditions which constitute non-cicatricial alopecia are Androgenetic alopecia [AGA], Alopecia areata [AA], Telogen effluvium [TE], of which AGA is the commonest. The development of new hair follicles following birth, barring a few exceptions is not a possibility. Therefore, in spite of treating the underlying pathology, patches of scarring alopecia do not show re-growth of hair. Non-scarring alopecias, on the other hand are more amenable to treatment and will be the objects of this study, particularly, AGA, AA and TE. Dermoscopy, also known as Epiluminescence microscopy, or Skin surface microscopy is a non-invasive, in-vivo technique, most commonly used for viewing pigmented skin lesions. The term “Trichoscopy” was coined for dermoscopy of hair and scalp. Trichoscopic evaluation of the scalp is done on the basis of follicular patterns, interfollicular patterns and hair signs. Any condition affecting the scalp will have characteristic patterns, based on which diagnosis of the particular condition can be made. Aim: To study the dermoscopic findings in non-cicatricial alopecia. (Androgenetic Alopecia, Alopecia Areata and Telogen Effluvium ) Materials and method: This study was a cross sectional study consisting of 1000 patients clinically diagnosed as having Androgenetic alopecia, alopecia areata or Telogen effluvium, irrespective of age or sex. Patients having scarring alopecia or non-scarring alopecia due to other conditions were excluded from the study. Clinical photographs were taken after informed consent and hair pull test was performed. Trichoscopic examination was done on six areas of the scalp with the addition of 2 areas in alopecia areata. The findings were tabulated and the prevalence of each trichoscopic feature in the three types of alopecia was calculated. Results: This study showed that among 100 patients with non-cicatricial alopecia, the majority had AGA ( 47% ), AA ( 21% ) and TE ( 21% ) were of equal prevalence and 11% had a combination of alopecias. The male: female ratio for AGA was 8:1, AA was 1.1:1 and TE was 1:20 showing that AGA is more common in males, TE is more common in females and AA has no significant difference in the sex distribution. Maximum number of patients (38% ) were in the age group of 21 – 30 years. On examination, pallor was more prevalent in patients of TE ( 52% ) and hair pull test was positive in all cases of TE and positive at periphery of lesions in 62% patients of AA. The characteristic follicular features on Trichoscopy observed in AGA were peripilar sign ( 29% < 4 fields; 49% > 4 fields ), yellow dots ( 49% < 4 fields ) and empty hair follicles ( 32% < 4 fields; 6% > 4 fields ). The characteristic hair shaft pattern observed was vellus hair (19% < 4 fields; 53% > 4 fields). Variation in hair shaft diameter was more prevalent in fronto-temporal areas ( 80% ) and was absent in occipital area. The prevalence of single hair pilosebaceous units was more prevalent in fronto-temporal areas ( 27% < 4 fields; 64% > 4 fields ) than in occipital area ( 28% ). The characteristic follicular features of AA on Trichoscopy were black dots ( 19% < 4 fields; 66% > 4 fields ), yellow dots ( 62% < 4 fields; 19% > 4 fields) and empty hair follicles ( 14% < 4 fields; 19% > 4 fields ). The characteristic hair patterns were broken hair ( 80% < 4 fields; 10% > 4 fields ), exclamation mark hair ( 57% < 4 fields ), vellus hair ( 43% < 4 fields ), pigtail regrowing hair ( 29% < 4 fields ), upright regrowing hair ( 23% < 4 fields ), zig-zag hair ( 19% < 4 fields ) and monilethrix-like hair ( 10% < 4 fields ). TE is said to be a disease of exclusion on Trichoscopy. The characteristic finding is that the variation in hair shaft diameter is prevalent in fronto-temporal ( 14% ) and occipital areas ( 71% ). It is important to differentiate this condition from AGA, where-in the variation in hair shaft thickness is present in fronto-temporal areas and absent in occipital area. The follicular features present in TE are peripilar sign ( 40% < 4 fields ), yellow dots ( 29% < 4 fields), upright regrowing hair ( 14% < 4 fields ) and vellus hair (10% < 4 fields). The majority of patients having combination of alopecias were those with the combination of AGA and TE ( 63.6% ). The characteristic features in them is that vellus hair and variation in hair shaft diameter are more pronounced in fronto-temporal areas than occipital area. Conclusion: According to this study, Trichoscopic features of alopecia areata are characteristic and may prove invaluable in the treatment of the condition. Androgenetic alopecia has characteristic trichoscopic features as well, but it can be confused with Telogen effluvium. To differentiate one from the other, it has to be kept in mind that the findings in Androgenetic alopecia spare the occipital area, whereas Telogen effluvium involves the occipital area. But, these conditions often co-exist. Trichoscope is a useful tool for diagnostic purposes and to monitor the response to treatment.