Background. Using both vertical and transverse sections is preferred for histopathological diagnosis of alopecia. However, in cases in which only a single biopsy is taken, it is not clear which type of sectioning is better.
Aim. To compare the diagnostic value of transverse and vertical sections.
Methods. In total, 53 patients with alopecia were enrolled in the study. Two biopsies were taken from each patient, and cut into either transverse or vertical sections. The clinical and histopathological findings were evaluated together for the definitive diagnosis. After the study period, a pathologist randomly re-evaluated the sections. We compared the histopathological diagnoses with the definitive diagnoses, and determined the sensitivity and specificity of each method.
Results. A definitive diagnosis was made for 47 patients (88.7%). Of these, 30 (63.8%) had noncicatricial and 17 (36.2%) had cicatricial alopecia, and the diagnosis was made by transverse and vertical sections for 43 (91.5%) and 39 (88%), respectively (P > 0.05; sensitivity; 91.5% vs. 82%). All 30 patients with noncicatricial alopecia were diagnosed by transverse sections, and 25 (83.3%) of the 30 were diagnosed with vertical sections (P = 0.05; sensitivity 100% vs. 83.3%). Of the 17 patients with cicatricial alopecia, 13 (76.5%) and 14 (82.4%) patients were diagnosed by transverse and vertical sections, respectively (P > 0.05; sensitivity 76.5% vs. 82.4%). Five patients with lichen planopilaris were diagnosed by vertical sections, and one by transverse sections. There were several limitations to the study: (i) statistical subtype analysis could be performed only for alopecia areata; (ii) no conclusion could be drawn about the interobserver reliability of two sections; and (iii) having the pathologist-blinded study performed retrospectively might have caused a recall bias.
Conclusion. If only a single biopsy specimen is available, it may be preferable to have transverse sections in cases of suspected noncicatricial alopecia, and vertical sections in cases of suspected lichen planopilaris. Either type of sectioning is suitable for cicatricial alopecia when lichen planopilaris is clinically unlikely.