Based on the following observations, we diagnosed this case as drug-induced lupus: the patient’s skin eruptions appeared after drug administration; imaging and clinical findings indicated that the malignancy remained stable during both the onset and exacerbation of the skin eruptions; and two months after discharge, although malignancy progressed, the anti-SSA/Ro antibodies became weakly positive, the ANA titer was considered negative, accompanied by an improvement in the skin eruptions. The gene discussed is BTG3; the disease is systemic lupus erythematosus.