Apalutamide, an oral
androgen receptor signaling inhibitor, is approved for the treatment of non-metastatic
castration-resistant
prostate cancer and metastatic
prostate cancer. In the international randomized placebo-controlled clinical trials,
apalutamide was associated with a higher rate of
rash than placebo. However, given that reports from a dermatological perspective are limited, the
skin manifestations and histopathology of the skin lesions caused by
apalutamide are largely unknown. Here, we report a case of
apalutamide-induced
drug eruption. A 66-year-old man developed itchy maculopapular
erythema on the trunk and extremities 10 weeks after starting
apalutamide for progressive
prostate cancer. A biopsy specimen showed interface
dermatitis with perivascular lymphocytic infiltration in the upper dermis. The lymphocyte transformation test was positive for
apalutamide. The
skin manifestations improved after discontinuation of
apalutamide and treatment with topical
corticosteroids and systemic
prednisolone. A review of the dermatology literature on
apalutamide-induced
drug eruption yielded only six cases, including our case. Dermatologically, there were four cases of maculopapular
rash and two of
toxic epidermal necrolysis and histopathologically, there were three cases of interface
dermatitis, two of epidermal
necrosis, and one of spongiotic
dermatitis. Four patients had peripheral
eosinophilia. A lymphocyte transformation test was performed in three cases and was positive for
apalutamide in all cases. Except for the two cases of
toxic epidermal necrolysis, which were fatal, the skin eruptions appeared 10 weeks after starting
apalutamide. Considering the increasing number of patients with
prostate cancer being treated with
apalutamide, cases of
apalutamide-induced
drug eruption need to be accumulated and analyzed.