Extravasation of an antibody-drug conjugate: A case report of epidermal necrosis after trastuzumab-emtansine extravasation.

What Is Known And Objective: Trastuzumab-emtansine is an antibody-drug conjugate developed to decrease off-target toxicity. According to the product label, reactions secondary to extravasation are mild or moderate.

Case Summary: We report on a 51-year-old woman who developed epidermal necrosis after extravasation of trastuzumab-emtansine, which required surgical intervention. Six weeks later, the lesions were healed with residual hyperpigmentation.

What Is New And Conclusion: We describe the course of a case of severe toxicity following trastuzumab-emtansine extravasation. We provide treatment recommendations and recommend amending the information on the product label on extravasation.