PET-CT’s before and after single agent pembrolizumab. (A) A coronal fused PET-CT image of a 23-year-old woman with cHL shows intensely hypermetabolic bulky lymphadenopathy involving the entire anterior mediastinum, left axillary, bilateral supraclavicular, and subpectoral nodal stations before therapy with pembrolizumab. (B) After 3 cycles of pembrolizumab monotherapy, there was marked anatomic and metabolic improvement of the disease. The residual mass has fluorodeoxyglucose (FDG) activity similar to liver background uptake, with the exception of mild FDG hypermetabolism in the anterior mediastinum (arrow), Deauville 4. (C) A coronal fused PET-CT image of another 23-year-old woman with cHL shows intensely hypermetabolic bulky lymphadenopathy involving the anterior mediastinum and the left axillary and left subpectoral nodal stations with a small right subpectoral lymph node before therapy. (D) After 3 cycles of pembrolizumab monotherapy with CMR, Deauville 3.