Contribution of immunophenotype to the investigation and differential diagnosis of Burkitt lymphoma, double-hit high-grade B-cell lymphoma, and single-hit MYC-rearranged diffuse large B-cell lymphoma.

BACKGROUND: There are no immunophenotypic guidelines for the investigation of MYC-rearranged lymphomas. We aimed to identify simple immunophenotypic features that would help to differentiate between MYC-rearranged lymphomas and guide cytogenetic analysis. METHODS: We reviewed diagnostic samples from patients diagnosed with Burkitt lymphoma (BL), double-hit lymphoma (DHL), MYC-rearranged diffuse large B-cell lymphoma (MYC-DLBCL), and standard (non-MYC-rearranged) DLBCL over the last decade in our Institution. Using flow cytometry (with antibodies CD20, CD10, CD38, bcl-2, Ki-67, FMC-7, CD43, CD27, CD79b, CD23, and CD22) we determined antigen% expression and median-fluorescence intensity ratios (MFIR). The forward scatter (FS) and side scatter (SS) characteristics of tumor B-cells were compared with normal T-cells (B/T ratios) for patients with MYC-rearranged lymphomas. RESULTS: We identified 51 patients of whom 14 had BL, 10 had DHL (6 MYC+/BCL2+; 4 MYC+/BCL6+), 8 MYC-DLBCL, and 19 standard DLBCL. The significant differences (p <.05) were: higher CD38% in BL than standard DLBCL; higher CD10% in BL and DHL versus MYC-DLBCL and standard DLBCL; higher CD10MFIR in BL than MYC-DLBCL and standard DLBCL; higher Ki-67% in BL than DHL and MYC-DLBCL; higher bcl-2% in DHL than BL; higher FMC-7% in BL than MYC-DLBCL and standard DLBCL; and lower SS (B/T) ratio in DHL than MYC-DLBCL. CONCLUSIONS: The combination of CD38% > 90, CD10% > 80, CD10MFIR > 10, bcl-2% < 30, and Ki-67% > 70 was characteristic of BL. "Deviation" from these cut-offs should raise suspicion for DHL and, therefore, BCL2 and/or BCL6 FISH is required. We also found that a diagnosis of DHL rather than of MYC-DLBCL was significantly associated with CD10% > 60, Ki-67% > 50, and SS (B/T) <1.5.

Flow cytometry as a diagnostic tool in the early diagnosis of aggressive lymphomas mimicking life-threatening infection.

Aggressive lymphomas can present with symptoms mimicking life-threatening infection. Flow cytometry (FC) is usually recommended for the classification and staging of lymphomas in patients with organomegaly and atypical cells in effusions and blood, after the exclusion of other possible diagnoses. FC may also have a place in the initial diagnostic investigation of aggressive lymphoma. Three cases are presented here of highly aggressive lymphomas in young adults, which presented with the clinical picture of fever of unknown origin (FUO) in patients severely ill. All followed a life-threatening clinical course, and two developed the hemophagocytic syndrome (HPS), but microbiological, immunological, and morphological evaluation and immunohistochemistry (IHC) failed to substantiate an early diagnosis. FC was the technique that provided conclusive diagnostic evidence of lymphoma, subsequently verified by IHC. Our experience with these three cases highlights the potential role of FC as an adjunct methodology in the initial assessment of possible highly aggressive lymphoma presenting with the signs and symptoms of life-threatening infection, although the definitive diagnosis should be established by biopsy. In such cases, FC can contribute to the diagnosis of lymphoma, independently of the presence of HPS.

Report of an HIV and HHV-8 negative case of primary effusion lymphoma with idiopathic T4 lymphocytopenia.

Although primary effusion lymphoma (PEL) is usually associated with human herpes virus-8/Kaposi sarcoma herpes virus (HHV-8/KSHV) and human immunodeficiency virus (HIV), there are several reports of HHV-8/KSHV and HIV negative cases, mainly in the setting of immunodeficiency. Here, we report the second case of PEL associated with idiopathic T4 lymphocytopenia (ICL), which was HHV-8/KSHV negative, HIV negative and Epstein-Barr virus positive, while no other causative agents for immunodeficiency were documented. Flow cytometry revealed a hyperdiploid and highly mitotic large B-cell population, CD30, EMA, CD66, CD38 and CD71 positive. The malignant lymphoma cells showed atypia with prominent nuclei and basophilic vacuolated cytoplasm, while cytogenetic analysis with fluorescent in situ hybridization showed trisomy 18. The patient was administered R-COP chemotherapy, but no remission was achieved, up to 3 months from diagnosis.