A study of the histopathological features of alopecias on transverse sections of scalp biopsies

Background: Transverse sections of scalp biopsies are performed for the assessment of alopecias and are considered advantageous over vertical sections. Aim: The aim was to study the histopathological features of alopecias on transverse sections of scalp biopsies. Methods: It was a descriptive study. Clinically confirmed cases of noncicatricial and cicatricial alopecias were subjected to 4 mm scalp biopsies, which were sectioned transversely and analyzed. Biopsies obtained from occipital region of androgenetic alopecia (AGA) cases were taken as controls. Results: Biopsies from 41 cases were assessed, including male and female AGA, alopecia areata (AA), trichotillomania, lichen planopilaris (LPP), discoid lupus erythematosus (DLE), and folliculitis decalvans (FD). Normal scalp (control) biopsies showed the median total number of hair follicles of 35 (32–37), anagen:telogen/catagen ratio of 17.5 (16.5–31), and terminal:vellus ratio of 15 (10.7–17.5). In AGA and AA, miniaturization and shift toward telogen and catagen hair were consistently observed. Peribulbar inflammation was seen in two-third of AA. Trichotillomania showed increased catagen hair and numerous pigment casts. In DLE, besides perifollicular inflammation, prominent peri-arrector pili and peri-eccrine inflammation were observed. Type of inflammatory infiltrate was similar in DLE and LPP (lymphocytic), whereas FD showed neutrophilic and plasma cell infiltrate, both around follicles and interstitially. Basal cell damage in the follicles and pigment incontinence were seen in majority of DLE and LPP patients. DLE also showed basement membrane thickening, mucin deposition, and telangiectasia. Reduction/absence of sebaceous glands and perifollicular fibrosis were observed in almost all cicatricial alopecias. Conclusion: Transverse sectioning may be a useful tool in the diagnosis of alopecias