Durable disease control of adult-onset xanthogranuloma with time-limited mitogen-activated extracellular kinase inhibition: a case report

Xanthogranuloma with mitogen-activated protein kinase pathway-activating mutations, such as the GAB2::BRAF fusion, may respond to mitogen-activated extracellular kinase (MEK) inhibitors, even in adult-onset cases. However, MEK inhibitors can cause delayed cardiotoxicity, even in patients with good initial tolerance, highlighting the need for close toxicity monitoring. This underscores the importance of treatment cessation trials, which may be reasonable to consider after 1–5 years of therapy, even if the disease was initially extremely aggressive.