Keywords: COVID-19 vaccine; HLH, hemophagocytic lymphohistiocytosis; PET-CT, positron emission tomography–computed tomography; SPTCL; SPTCL, subcutaneous panniculitis-like T-cell lymphoma; SUV, standardized uptake value; TCR, T-cell receptor; injection site reaction; subcutaneous panniculitis-like T-cell lymphoma; viral vector vaccine.