Acne fulminans is a rare severe disease with an abrupt onset. The disease is often associated with various systemic manifestations (fever, muscle and joint pain, SAPHO, RARA, and other syndromes) but can also occur individually. It is not uncommon for patients with a severe course of acne to have pronounced psychological problems. Sometimes, there are difficulties not only in the diagnosis but also in the management of such patients. The main features of the course, differential diagnosis, and treatment methods are described here. Current therapies include systemic glucocorticosteroids, retinoids, cyclosporine, and biologically active drugs with little experience of their use in such cases. We present a clinical case with a favorable outcome with Lidose isotretinoin treatment. The patient’s mother flatly refused corticosteroids administration to her child. Therefore, an individual therapeutic strategy based on a slow, gradual dose increase of Lidose isotretinoin and dose cumulation was selected, which allowed avoiding an acute exacerbation of the disease.