A mitogen-activated protein kinase kinase inhibitor induced compound skin toxicity with oedema in metastatic malignant melanoma

Summary We report three cases of skin toxicity associated with oral mitogen‐activated protein kinase kinase (MEK) inhibitor treatment for metastatic malignant melanoma (MM). All three patients developed oedema, and a single patient experienced eyelash trichomegaly. This is the first known report of eyelash trichomegaly secondary to MEK inhibitor use. We also discuss possible mechanisms for MEK inhibitor‐associated oedema development. This series supports the role of the dermatologist in the screening and management of patients in the rapidly developing oncology setting, as new targeted agents can give rise to marked skin toxicity.