Several prognostic indices have been reported for peripheral T-cell lymphoma (PTCL) and adult T-cell leukemia/lymphoma (ATL). The clinical features and prognosis of PTCL differ in a specified pathological diagnosis, whereas those of ATL are more diverse, even in the same clinical subtypes of acute, lymphoma, chronic, and smoldering. The establishment of a prognostic index is important not only for a risk-stratified treatment approach, but also for the preliminary evaluation of therapeutic findings by novel modalities, particularly in rare and aggressive diseases such as ATL. Five prognostic indices for PTCL-not otherwise specified and 6 prognostic indices for ATL are discussed herein. Recent advances in molecular analyses have facilitated prognostication using molecular profiles. In addition to the external validation of these prognostic indices, which are mostly established by clinical information, the development of novel indices by incorporating molecular profiles is warranted to improve the outcomes of patients through the selection of optimal treatments.

Outcomes of patients with histologic transformation (HT) of follicular lymphoma (FL) have been believed to be poor. The most common histologic subtype of transformation from FL is diffuse large B-cell lymphoma (DLBCL), which accounts for 90% of the cases, and the remaining 10% of the cases include classic Hodgkin lymphoma, high-grade B-cell lymphoma, plasmablastic lymphoma, B-acute lymphoblastic leukemia/lymphoma, histiocytic/dendritic cell sarcoma, and anaplastic large cell lymphoma-like lymphoma. Because the histologic criteria for the diagnosis of DLBCL transformed from FL are unclear, convenient histopathological criteria for HT are required. One of the proposed criteria of HT from our institute is the presence of diffuse architecture with a proportion of large lymphoma cells of ≥20%, and for challenging cases, Ki-67 index ≥50% is used as a reference. Patients with HT to non-DLBCL have poorer outcomes than those with HT to DLBCL; thus, rapid and accurate histologic diagnosis is desired. In this review, we discussed the recent literatures describing the histopathologic variety and proposal of definition of HT.

CD5-positive diffuse large B cell lymphoma (CD5+ DLBCL) is a high-risk lymphoma type. Recently, the PEARL5 (a Phase II trial of DA-EPOCH and Rituximab with HD-MTX therapy for newly diagnosed DLBCL with CD5 expression) study demonstrated the efficacy of the DA-EPOCH-R (cyclophosphamide, etoposide, doxorubicin, vincristine, prednisone, and rituximab)/HD-MTX (high-dose methotrexate) regimen for CD5+ DLBCL. In this report, we revealed the impact of the DA-EPOCH-R/HD-MTX regimen on the clinical course of CD5+ DLBCL in the real-world. We retrospectively compared CD5+ and CD5− DLBCL patients diagnosed from January 2017 to December 2020 and analyzed their clinicopathological characteristics, treatment, and prognosis. There was no difference in age, sex, clinical stage, and cell of origin; however, the CD5-positive group had higher lactate dehydrogenase levels and a worse performance status than the CD5-negative group (p=0.00121 and p=0.0378, respectively). International prognostic index (IPI) was worse in the CD5-positive group than in the CD5-negative group (p=0.0498), but NCCN-IPI (National Comprehensive Cancer Network-IPI) was no different between the two groups. The CD5-positive group was more frequently treated with the DA-EPOCH-R/HD-MTX regimen than the CD5-negative group (p =0.001857). Complete remission rate and 1-year overall survival did not differ between the CD5-positive and -negative groups (90.0% vs 81.4%, p=0.853; 81.8% vs 76.9%, p=0.433). We conclude that the DA-EPOCH-R/HD-MTX regimen is effective for CD5+ DLBCL in this single institute analysis.

Intravascular large B-cell lymphoma (IVL) is a rare type of lymphoma characterized by tumor growth selectively within the vessels. The 5^th edition of the World Health Organization classification defines IVL as a large B-cell lymphoma, the same as diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS). Since the clinical manifestations of IVL are nonspecific, the diagnosis is time-consuming, and the course is often fatal. Serum soluble interleukin-2 receptor (sIL-2R) and serum lactate dehydrogenase (LDH) levels are known to be elevated in a variety of lymphomas. However, the mechanism of sIL-2R elevation in B-cell lymphomas is not fully understood. In this study, we analyzed the serum level of laboratory findings, including sIL-2R and LDH, as well as the presence of B symptoms in 39 patients with IVL, and compared them with 56 patients with stage IV DLBCL. Both sIL-2R and LDH levels were significantly higher in IVL than in DLBCL (p = 0.035 and p = 0.002, respectively). In IVL, there were no significant differences in both sIL-2R and LDH levels between patients with and without B symptoms (p = 0.206 and p = 0.441, respectively). However, in DLBCL, both sIL-2R and LDH levels were significantly higher in the presence of B symptoms (p = 0.001 and p < 0.001, respectively). The high sIL-2R and LDH levels in IVL may be related to the peripheral blood microenvironment, but further studies are needed to verify this.

TAFRO syndrome is a rare systemic inflammatory disease characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis, and organomegaly. We encountered a case of calreticulin mutation-positive essential thrombocythemia (ET) with TAFRO syndrome-like features, followed by a rapid fatal course. The patient had been on anagrelide therapy for approximately three years for management of ET; however, she suddenly stopped going for follow-up and discontinued the medicine for a year. She presented with fever and hypotension, suggestive of septic shock, and was transferred to our hospital. The platelet count at the time of admission to another hospital was 50 × 10⁴ / μL; however, it decreased to 25 × 10⁴ / μL upon transfer to our hospital and further decreased to 5 × 10⁴ / μL on the day of her death. In addition, the patient showed remarkable systemic edema and progression of organomegaly. Her condition suddenly worsened and led to her death on the 7th day of hospitalization. Postmortem, serum and pleural effusion interleukin (IL)-6 and vascular endothelial growth factor (VEGF) levels were significantly increased. Consequently, a diagnosis of TAFRO syndrome, since she met the diagnostic criteria for clinical findings and had high cytokine concentrations. Dysregulation of cytokine networks has also been reported in ET. Therefore, concurrent ET and TAFRO syndrome may have further triggered cytokine storms and contributed to the aggravation of the disease on development of TAFRO syndrome. To the best of our knowledge, this is the first report of complications seen in a patient with TAFRO syndrome due to ET.

A 71-year-old Japanese man presented with severe thrombocytopenia. A whole-body CT at presentation showed small cervical, axillary, and para-aortic lymphadenopathy, leading to suspicion of immune thrombocytopenia due to lymphoma. Biopsy was difficult to perform because of severe thrombocytopenia. Thus, he received prednisolone (PSL) therapy and his platelet count gradually recovered. Two and a half years after PSL therapy initiation, his cervical lymphadenopathy slightly progressed without other clinical symptoms. Hence, a biopsy from the left cervical lymph node was performed, and he was diagnosed with nodal peripheral T-cell lymphoma (PTCL) with T follicular helper (TFH) phenotype. Due to various complications, we continued treatment with prednisolone alone after the diagnosis of lymphoma; however, there was no further increase in lymph node enlargement and no other lymphoma-related symptoms for one and a half years after diagnosis. Although immunosuppressive therapy has been reported to produce a response in some patients with angioimmunoblastic T-cell lymphoma, our experience suggests that a similar subset may exist in patients with nodal PTCL with TFH phenotype, which has the same cellular origin. Immunosuppressive therapies may constitute an alternative treatment option even in the era of novel molecular-targeted therapies, especially for elderly patients who are ineligible for chemotherapy.

We present the case of an 85-year-old male patient diagnosed with human herpesvirus 8 (HHV8)-negative effusion-based lymphoma (EBL) that developed from long-lasting pleural effusion (PE) induced by dasatinib treatment for chronic myeloid leukemia (CML). After the onset of this disorder, dasatinib treatment was discontinued and drainage was performed to regress the effusion. The major molecular response (MMR) was thus lost. The patient did not tolerate nilotinib treatment, but bosutinib was successful in restoring MMR. During these clinical courses, the patient suffered from a recurrence of EBL, which was treated with rituximab-based chemotherapy. The PE sample just before the 3^rd cycle of chemotherapy revealed the proliferation of CD57-positive T cells, along with the disappearance of lymphoma cells. Anti-tumor immunity may have been activated following the immunochemotherapy in the undisturbed immunological environment when both EBL and CML almost regressed. After four cycles of R-CVP therapy, the patient has been in remission for 16 months and no longer requires drainage.

Scarce data are available regarding neoplastic PD-L1 (nPD-L1, clone SP142) expression in cutaneous T-cell lymphoma. We recently documented a possible association of increased nPD-L1 expression with tumor progression to secondary nodal involvement in two cases of CD30-positive primary cutaneous large T-cell lymphoma (PC-LTCL) (Pathol Int 2020;70:804). Notably, the nodal sites exhibited classic Hodgkin lymphoma (CHL) mimicry related to both morphology and tumor microenvironment (TME), i.e., abundant PD-L1-positive tumor-associated macrophages and low-level PD-1 expression on T-cells. Immunohistochemistry highlighted distinctly different nPD-L1 positivity between the cutaneous and nodal lesions. In the present study, we aimed to validate this unique phenomenon in a larger series of four cases with FISH and targeted-capture sequencing (targeted-seq) analysis. We retrospectively identified two more cases of CD30-positive PC-LTCL with secondary nodal involvement among all patients consecutively diagnosed between 2001–2021. All cases immunohistochemically exhibited elevated nPD-L1 expression on ≥50% of lymphoma cells in nodal tumors, clearly contrasting with the scarce nPD-L1 positivity (≤1%) in cutaneous tumors. Moreover, all nodal lesions exhibited CHL-like TME, with abundant PD-L1-positive tumor-associated macrophages and low-level PD-1 expression on T cells, although the CHL-like morphology was limited in the two original cases. None showed CD274/PD-L1 copy number alteration by FISH analysis, or structural variations of PD-L1 3’-UTR by targeted-seq analysis. These findings indicated that nPD-L1 expression is linked with tumor progression and CHL-like TME in nodal involvement of PC-LTCL. Interestingly, one autopsied case exhibited heterogeneity of nPD-L1 expression at different disease sites.