Erythroderma with brentuximab vedotin (skin side effects in mycosis fungoides)

Brentuximab vedotin (BV, SNG35) is a monoclonal drug that is effective in the treatment of both systemic and cutaneous T-cell lymphomas [1–4]. The standard dosage of BV is 1.8 mg/kg body weight (b.w.) every 21 days for a maximum of 16 cycles [2–4]. Despite being well tolerated, adverse effects (AEs) have been reported, most of which are reversible and mild to moderate. The most common AE is peripheral neuropathy [2–4]. Apart from recently described BV-induced alopecia [5], skin AEs (SAEs) due to BV have been categorized as “rashes”. Here we report our findings on SAEs due to BV. A literature search for “mycosis fungoides” (MF) cases treated with BV retrieved ten cases in the last two years. Three of these patients experienced SAEs (median age 54 years). One patient was in stage IIB (Figure 1a) and two in stage IVA1. Initiating treatment with new concomitant medications was ruled out, but treatments that had started months or years before the SAEs were continued. BV was scheduled for a maximum of 16 cycles at the standard dosage. Before the onset of the SAE, an amelioration of MF was observed in all three cases. SAEs due to BV developed three cycles (median value, range 2–4 cycles) after starting BV. All three patients developed erythroderma (together with enanthem in one patient) (Figure 1b–d), and biopsies were performed in all patients to rule out any relapse of the disorder (Figure 2a–h). Histology showed a focal epidermotropic dermal infiltrate consisting of small to medium-sized lymphocytes (Figure 2b). Immunohistochemistry showed that cells in the infiltrate expressed CD8 molecules (only a few cells were CD4+) (Figure 2d, f), as well as cytotoxic markers such as TIA-1 (Figure 2h) and granzyme B. Such histologic and immunophenotypic features were in contrast with the predominance of CD4+ over CD8+ elements of the diagnostic biopsy, which did not show any expression of TIA-1 (Figure 2a, c, e, g). Moreover, the switch from monoclonal to polyclonal TCRs corroborated the diagnosis of an SAE Erythroderma with brentuximab vedotin (skin side effects in mycosis fungoides) Clinical Letter