The value of Trichoscopy and Histopathology in the diagnosis of post-COVID-19 telogen effluvium

Introduction: Telogen effluvium (TE) is a recognized sequel of COVID-19 infection, often exhibiting an accelerated onset that suggests a pathomechanism distinct from classical TE. This study aims to define the unique trichoscopic and histopathological features of post-COVID-19 TE and to correlate these novel findings with prior systemic disease severity. Methods: Trichoscopy images and pathology specimens of 13 patients (12 women, 1 man; mean age 46.2 years) who developed TE after PCR-confirmed COVID-19 infection were retrospectively reviewed. Statistical analysis correlated trichoscopic findings with the need for supplementary oxygen during acute infection. Results: Trichoscopy showed thick, livedoid arborizing vessels in most cases, with giant serpiginous vessels in 38% of patients. The presence of giant vessels showed a strong statistical correlation with the requirement of supplementary oxygen during hospitalization (p=0.001). Histopathology confirmed a catagen/telogen shift and consistently revealed a superficial perivascular and perifollicular lymphocytic infiltrate in all cases. Conclusion: The vascular pattern can distinguish post COVID-19 TE. The perifollicular lymphocytic infiltrate supports a direct viral or localized immune-mediated insult.