Answer :
A. Discontinue imatinib and start low-dose prednisolone at 0.5 mg/kg once daily.
J.L. presents with persistent fever, a maculopapular rash, and elevated eosinophils shortly after starting imatinib. These clinical signs, along with the laboratory findings, suggest drug reaction with eosinophilia and systemic symptoms (DRESS).
DRESS is a severe hypersensitivity reaction, which requires immediate intervention to prevent further complications, including organ failure. In this case, it is important to discontinue the offending drug, imatinib, immediately. Additionally, treatment with corticosteroids such as prednisolone can help manage the inflammation and immune response associated with DRESS.