Telogen Effluvium after SARS-CoV-2 Infection: A Series of Cases and Possible Pathogenetic Mechanisms

INTRODUCTION: Physicians have largely studied the cutaneous involvement of coronavirus disease 2019 (COVID-19), but only few reports have focused on telogen effluvium (TE) as a possible sequela of COVID-19. We assessed 14 cases of hair loss occurring after SARS-CoV-2 infection using trichoscopy and trichogram to investigate patterns related to COVID-19. Furthermore, we discussed possible mechanisms involved in COVID-19 TE. CASE PRESENTATION: Fourteen individuals were referred to our post-COVID-19 dermatology office complaining acute hair loss after SARS-CoV-2 infection. Clinical evaluation included pull test, trichoscopy, and trichogram. CO­VID-19 TE occurred after a median of 2 months (range 1–3 months) following SARS-CoV-2 infection. The median duration of hair loss was 5 months (range 1–6 months). Trichoscopy showed variable but typical TE patterns. Trichogram showed different telogen/anagen ratio depending on the interval between onset of hair loss and trichological visit. DISCUSSION/CONCLUSION: Our cases showed TE between 1 and 3 months after the onset of SARS-CoV-2 infection, thus earlier than classic TE. Trichoscopic features and trichogram showed no variations from classic TE. Different pathogenetic mechanisms including pro-inflammatory cytokines and direct viral damage on the hair follicle can be hypothesized; further studies on a larger sample are needed to better understand this condition.