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A 73-year-old man presented with malaise, fever, dysphagia and disseminated lymphadenopathy, with no evidence of pleural effusion or ascites. A diagnosis of conventional chronic lymphocytic leukemia (CLL) had been made 11 years earlier, and a single course of fludarabine and cyclophosphamide had been given two years earlier due to increased lymphocytosis, splenomegaly and widespread lymphadenopathy. A cervical lymph node biopsy at the time of the latest presentation showed on histopathologic examination. (panels A-C). involvement by CLL and nodules of large cells with focal peripheral sinusoidal involvement. The small lymphoid cells of the CLL areas were positive for CD20, CD5 (panel D), CD23, PAX-5, and LEF1, with 10% proliferation on Ki-67 immunohistochemical staining. On flow cytometric study these cells featured Kappa light-chain restriction (not shown). The large cells in solid nodules and sinuses featured prominent eosinophilic nucleoli and abundant cytoplasm, lacked expression of CD45, CD20 (panel E), CD138 and CD5, but were positive for EMA (panel F) CD30, MUM-1 (panel G), Lambda light chain, EBER (panel H) and HHV8 (panel I). Ki-67 stained over 90% of the large cells. Two distinct clonal peaks were detected by IgH polymerase chain reaction (not shown), both in samples from whole tissue and in samples obtained after macrodissection of the paraffin blocks. A bone marrow biopsy showed nodular involvement by CLL and no evidence of large cell lymphoma. The patient’s clinical condition deteriorated rapidly and he died a few weeks after presentation.

Richter’s syndrome complicating CLL has usually features of clonally related diffuse large B-cell lymphoma, and only rarely have other variants been described, including classic Hodgkin or plasmablastic lymphoma. Immunohistochemical detection of HHV-8 in our case rules out the alternative diagnostic possibility of plasmablastic lymphoma, and should be routinely perfomed in this setting. Old age and CLL-related immunesupression are likely of pathogenic significance in our patient.