The Value of Trichoscopy and Histopathology in the Diagnosis of Post-COVID-19 Telogen Effluvium

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.

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.

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.

Vascular patterns can distinguish post-COVID-19 TE. The perifollicular lymphocytic infiltrate supports a direct viral or localized immune-mediated insult.