We report a case of systemic lupus erythematosus in a 15-year-old girl with initial presentation as acute lupus pneumonitis. A fulminant course with pancytopenia and respiratory distress were developed 3 weeks after symptom onset. Chest radiographs revealed an interstitial pattern with miliary nodules over bilateral lower lung fields that mimics miliary tuberculosis. The patient was treated with intravenous immunoglobulin and antituberculosis drugs because the infection-associated hemophagocytic syndrome and pulmonary tuberculosis could not be excluded from the clinical course. The response to antituberculosis treatment, however, was poor and her respiratory condition deteriorated rapidly to impending respiratory failure 1 week after admission. Systemic lupus erythematosus with acute lupus pneumonitis was then diagnosed based on the fulminant clinical course and accordant laboratory results. Corticosteroid (methylprednisolone) and cytotoxic agent (cyclophosphamide) pulse therapies were applied twice and once, respectively. She recovered gradually after receiving the immunotherapy.