Extranodal NK/T cell lymphoma and lymphomatoid granulomatosis in a patient with chronic lymphocytic leukaemia: Case report for a new perspective on Richter syndrome.

Rationale: Richter syndrome (RS) defines the transformation of chronic lymphocytic leukemia (CLL) into a more aggressive lymphoma. Although the term RS is most often reserved for transformation of CLL into diffuse large B-cell lymphoma (DLBCL), and less frequently Hodgkin lymphoma , the list of cases with more variable presentations in the literature is growing. Patient concerns: A 71-year-old Caucasian man initially consulted an otolaryngologist for a 1-year history of nasal congestion. Diagnoses: The asynchronous occurrence of 2 rare angiocentric Epstein-Barr virus (EBV)-related lymphoproliferative disorders in a patient with CLL, specifically clonally related lymphomatoid granulomatosis (LYG), and an extranodal NK/T-cell lymphoma, nasal type, are described herein. Interventions: Radiation therapy and a regimen of cis-platinum were administered for the NK/T cell lymphoma, and ibrutinib for LYG. Outcomes: The patient remains in complete clinical remission 8 years after the diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma and recurrent extranodal NK/T cell lymphoma, and 2 years after the diagnosis of clonally related LYG. Lessons: Although the precise pathogenesis of RS remains incompletely understood, various molecular alterations, in particular long-term immunosuppression, may lead to RS, similar to the causal link existing between non-Hodgkin lymphomas and HIV infection, and post-transplantation lymphoproliferative disorders. EBV infection is linked to the pathogenesis of several types of lymphomas and found in a subset of patients with RS; immunosuppression, in the context of CLL or other pathological conditions or pharmacological agents, can disrupt the fine balance between virus and the host immune system, and result in EBV-driven lymphoproliferations of B-, T-, or NK-cell origin. The findings of our literature review thus suggest that such non-diffuse large B-cell lymphoma , non-Hodgkin lymphoma CLL transformations, may be considered as rare variants of RS.