The patient went on to have a biopsy.
Histology
Sections of brain tissue show a dense infiltrate composed of predominantly small lymphocytes, histiocytes and scattered individual and small clusters of atypical lymphoid cells. The large atypical cells demonstrate frequent binucleation with prominent nucleoli and voluminous pale eosinophilic cytoplasm with perinuclear clearing and vacuolation.
Immunohistochemical results indicate the large atypical cells stain as follows:
- CD20 patchy positive
- CD30 strong positive
- EBER-CISH positive
- OCT2 positive
- PAX5 weak positive
- BOB1 weak positive
- CD79a weak positive
- MUM1equivocal
- CD45 negative
The background small lymphocytes show a mixed population on CD3+ T-cells and CD20+ B-cells, together with aggregates CD68+ histiocytes.
Comment: The presence of Reed-Sternberg-like cells with a compatible immunophenotype favours a diagnosis of classical Hodgkin lymphoma occurring in the setting of previous solid-organ transplantation. Other forms of post-transplant lymphoproliferative disorders (PTLD), such as the polymorphic variant, are considered less likely. There are no features to indicate a monomorphic variant of PTLD.
FINAL DIAGNOSIS: Classical Hodgkin lymphoma-like post-transplant lymphoproliferative disorder (PTLD).