Severe complications of nivolumab monotherapy in an adolescent with malignant melanoma.

This study presents a case of a 17-year-old female patient who had previously undergone surgical resection of melanoma in the right periscapular area. She was administered adjuvant treatment with the PD-1 inhibitor nivolumab as monotherapy. The mechanism of action of this drug is based on increased stimulation of the immune system. The patient developed a series of complications including capillary leak syndrome and hypothyroidism after the fifth cycle of therapy, as a result of dysregulation of immunity. Nivolumab treatment had to be discontinued and glucocorticosteroids were administered as a salvage therapy. After several months, two relapses developed in the subcutaneous tissue - first in the left and then in the right iliac region, confirmed as distant metastases of malignant melanoma, treated with resections of the lesions and intensity-modulated radiation therapy. Follow-up imaging studies and clinical examinations showed no metastases or pathologically enlarged lymph nodes.