1.1 Virus induced maculopapular exanthema
Although skin biopsies are rarely taken from viral skin lesions, because
the features observed are mostly not very specific, biopsies might be an
option to differentiate viral exanthema from drug-induced exanthema in
COVID-19 patients, in these cases it is essential to do the differential
diagnosis and rule out the pharmacological cause.
To distinguish infectious exanthema from exanthema induced by
drug-hypersensitivity reactions, histologic features and immunologic
changes in the skin might help to diagnostically differentiate both
entities.
Immunologic features of maculopapular virus exanthema known so far are
summarized in Fig. 5A. Typical histologic features of infectious
exanthema induced by viremia or dissemination of infectious agents
through the blood are shown in Table 2 and Fig. 6A.