The Clinical and Histopathological Features of Cutaneous Immune-related
Adverse Events and Their Outcomes
Abstract
Background: Immune checkpoint inhibitors (ICIs) cause a variety of
inflammatory eruptions. A better understanding of the rash types,
histopathological findings, severity, and clinical courses is necessary
for appropriate managements of these eruptions. Only a few reports
reviewed ICI-induced inflammatory eruptions with detailed
histopathological findings. Methods: In this study, we retrospectively
reviewed 42 patients who were histopathologically diagnosed with
cutaneous immune-related adverse events (irAEs) following ICI therapy
between 2014 and 2020 at the Department of Dermatology of Kyushu
University Hospital. Results: Of the 42 patients (24 males, 18 females),
maculopapular rash (33/42, 78.6%), erythema multiforme (2/42, 4.8%),
lichenoid reaction (3/42, 7.1%), psoriasiform reaction (1/42, 2.4%),
bullous pemphigoid (1/42, 2.4%), scleroderma-like reaction (1/42,
2.4%), and Stevens-Johnson syndrome (1/42, 2.4%) were observed. The
clinical and histopathological findings of these eruptions were
equivalent to typical cases of common drug eruptions. The onset of
maculopapular rash was relatively early (more than half of events
occurred within 1 month), whereas lichenoid reactions and autoimmune
diseases occurred relatively late (4–8 m¬¬onths). With appropriate
treatment and/or interruption of ICIs, most rashes were improved (40/42,
95.2%). Conclusions: The ICI-induced inflammatory eruptions shared
similar clinical and histopathological features with classical
inflammatory eruptions, but a variety of inflammatory eruptions may
occur with different degrees of severity. Dermatologists play an
important role in providing specialized care for cutaneous
immune-related adverse events.