A pericardial biopsy was performed for possible secondary malignancy due to the absence of involvement in another area of ​​the whole body, and it was found to be compatible with CD20 (+), BCL2 (+), BCL6 (+), C-MYC (−) immunoreactivity nongerminal center type DLBCL recurrence. Here, BCL6 is linked to diffuse large B-cell lymphoma.