First Report of Asymptomatic Solitary High-Grade B-Cell Lymphoma NOS: An Enigmatic Entity

Abstract

Background High-grade B cell lymphoma (HGBL) is a new disease entity introduced by WHO in 2016, including two types: HGBL with a double hit (DH) or triple hit (TH) and HGBL, not otherwise specified (NOS). HGBL DH/TH are defined by genetic rearrangements of specific oncogenes MYC, BCL2 and/or BCL6, while HGBL NOS is defined purely base on morphology in the absence of these genes. HGBL DH/TH is known for its poor prognostication given its propensity to rapidly progress and disseminate, however HGBL NOS remains ill-defined and poorly understood with no tangible literature describing its clinical nature and therapeutic susceptibility. Case presentation A 76-year-old post-menopausal woman with no significant PMH presented for evaluation of painless hematuria during a routine office visit. Evaluation with imaging showed a suspicious incidental liver mass concerning for possible metastatic or primary liver cancer. Obtained labs were unremarkable, including serum LDH, serological testing for hepatitis B/C and HIV1/2, and typical tumor markers. PET scan showed focal uptake of tracer in liver with no nodal involvement. Liver biopsy revealed diffuse infiltration by atypical lymphocytes. Immunohistochemical analysis showed CD20 and CD10 positivity, negative CD30, and high Ki-67 proliferation rate of 100%, however the absence of MYC, BCL6, BCL2, and t(8;14) rearrangements on FISH ruled out Burkitt and DH/TH lymphoma, consistent with HGBL-NOS. Following discussions with Henry Ford Lymphoma Tumor Board, patient was treated with six cycles of R-CHOP, where follow-up imaging indicated remission of her lymphoma. Conclusion This represents an extraordinary first report of HGBL NOS manifesting as an isolated primary hepatic lymphoma in the complete absence of clinical symptoms. The significance of this case lies in its atypical extra-nodal site of involvement and total absence of clinical symptoms and serological markers, underscoring the unfulfilled need to further describe this enigmatic entity.