Quantitative Analysis of Immune-Reactive Cells among Leukocytes Is Useful for the Diagnosis of Drug Eruptions Caused by Bexarotene

Bexarotene is a third-generation retinoid X receptor-selective retinoid that has been approved for use in the treatment of cutaneous T-cell lymphomas (CTCLs). Since the objective response rate of bexarotene is relatively high, with no racial differences, bexarotene can be administered to patients with phototherapy-resistant early CTCL as one of the first-line therapies in real-world clinical practice. Although various adverse events caused by bexarotene have been reported, there have been no reports of drug eruptions caused by bexarotene. One of the possible reasons is that it is difficult to distinguish a drug eruption from recurrence of CTCL, histologically. In this report, drug eruptions in 2 patients with CTCL treated with bexarotene diagnosed by quantitative analysis of immunohistochemical staining by digital microscopy are described.