Acne Fulminans Systemic

A 16-year-old male presents with a 2-week history of severe acne with abrupt onset of numerous painful lesions on the chest, back, and shoulders. On examination, the structure marked **A** (hemorrhagic ulcerative inflammatory nodules with necrotic crusts) is accompanied by fever (39.5°C), polyarthralgia affecting the knees and hips, malaise, and weight loss. Laboratory investigations reveal leukocytosis with neutrophilia, elevated ESR and CRP, and microscopic hematuria. Radiographs show lytic lesions in the clavicles and sternum. Which of the following is the most appropriate INITIAL management strategy for this patient?