Immunohistochemical Expression of Angiotensin-Converting Enzyme 2 in the Skin of Patients Affected by COVID-19

After many recorded cases of acute pneumonia of unknown cause, the World Health Organization announced COVID-19 as the start of a new coronavirus disease pandemic in 2019. Angiotensin-converting enzyme-2 (ACE2) is reduced by a protease known as transmembrane serine type 2 in the host cell, which then activates the S protein of SARS-CoV-2 regulating coronavirus entry into the host cells.

The aim of this study was to assess the immunohistochemical expression of ACE 2 in the skin of patients affected by COVID-19 with and without cutaneous manifestations and to correlate ACE2 expression with clinical and pathologic parameters.

Skin biopsies were obtained from skin lesions of 25 patients presenting with cutaneous manifestations and from the left forearm of 22 patients without cutaneous manifestations. The specimens were processed for evaluation of histopathologic changes and ACE2 immunohistochemical evaluation.

Positive ACE2 expression was significantly higher in patients without cutaneous manifestations (96%) than those with cutaneous manifestations (72.7%). Positive ACE2 expression in the skin of affected patients was significantly associated with the presence of comorbidities, positive family history, high ABCD score, elevated lactate dehydrogenase, high D-dimer, rapid respiratory rate, and low oxygen saturation.

The skin could be involved in COVID-19 infection in the form of inflammatory changes, such as pityriasis rosea-like lesions. Patients with COVID-19 who presented with cutaneous manifestations are usually less severe. The presence of ACE2 in the skin of patients with COVID-19 is an indicator of worse status. Patients with COVID-19 without skin manifestations showed higher positivity for ACE2, which may explain the severity of the cases.