The prognostic impact of FLT3-ITD, NPM1 and CEBPa in cytogenetically intermediate-risk AML after first relapse.

We evaluated the impact of FLT3-ITD, NPM1 mutations, and double mutant CEBPa (dmCEBPa) on overall survival (OS) after relapse in patients with cytogenetically intermediate-risk acute myeloid leukemia (AML) who were treated with chemotherapy alone in the first remission (CR1). Patients aged 16-65 years diagnosed with cytogenetically intermediate-risk AML, and who achieved CR1 were included. We retrospectively analyzed FLT3-ITD, NPM1 mutations and CEBPa using samples obtained at diagnosis, which therefore did not affect the therapeutic decisions. Among 235 patients who had achieved CR1, 152 relapsed, and 52% of them achieved second CR. The rate of achieving second CR was significantly higher (85%) in those with dmCEBPa. Patients with FLT3-ITD had significantly worse OS after relapse than those without (19% vs 41%, p = 0.002), while OS was comparable between patients with and without NPM1 mutations (37% vs 34%, p = 0.309). Patients with dmCEBPa had improved OS than those without (61% vs 32%, p = 0.006). By multivariate analysis, FLT3-ITD was independently associated with worse OS after relapse [hazard ratio (HR) 1.99, 95% CI 1.27-3.12, p = 0.003], and dmCEBPa with improved OS (HR 0.40, 95% CI 0.17-0.93, p = 0.033). Our data show that screening for these mutations at diagnosis is useful for facilitating effective therapeutic decision-making even after relapse.

Final analysis of the JALSG Ph+ALL202 study: tyrosine kinase inhibitor-combined chemotherapy for Ph+ALL.

The Japan Adult Leukemia Study Group (JALSG) Ph+ALL202 study reported a high complete remission (CR) rate for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) patients treated with imatinib-combined chemotherapy. However, the long-term treatment efficacy remains uncertain. Here, we report a final analysis of the JALSG Ph+ALL202 study. The outcomes were compared with those of the JALSG ALL93 and ALL97 studies, which were conducted in the pre-imatinib era. Ninety-nine newly diagnosed Ph+ALL patients were enrolled in Ph+ALL202 (median age, 45 years; median follow-up, 4.5 years). CR was achieved in 96/99 (97%) patients. Fifty-nine of these 96 patients (61%) underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) in their first CR (CR1). The 5-year overall and disease-free survival (DFS) rates were 50 and 43%, respectively, which were significantly higher compared to those in the pre-imatinib era (15 and 19%, respectively). Multivariate analysis revealed that imatinib administration, allo-HSCT in CR1, and a white blood cell count < 30 × 109/L were favorable independent prognostic factors for long-term DFS. Improved odds of receiving allo-HSCT and a lower relapse rate leaded to good long-term outcomes. The 3-year DFS tended to be higher in PCR-negative than that in PCR-positive patients (29 vs. 14%) in the non-HSCT patients, and this tendency was also seen in the allo-HSCT patients (59 vs. 50%). The higher rate of CR upon imatinib use may have contributed to these improvements.

Combined treatment with benzo[a]pyrene and 1α,25-dihydroxyvitamin D3 induces expression of plasminogen activator inhibitor 1 in monocyte/macrophage-derived cells.

Benzo[a]pyrene (BaP) is an environmental pollutant found in cigarette smoke and is implicated as a causative agent of tobacco-related diseases, such as arteriosclerosis. In contrast, vitamin D signaling, which is principally mediated by conversion of vitamin D to the active form, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3], decreases cardiovascular disease risk. However, combined treatment with BaP and 1,25(OH)2D3 enhances BaP toxicity, including BaP-DNA adduct formation. We further investigated the cross-talk between BaP and 1,25(OH)2D3 signaling pathways, and found that combined treatment with these compounds induces mRNA and protein expression of plasminogen activator inhibitor 1 (PAI-1) in monocyte/macrophage-derived THP-1 and U937 cells. Protein synthesis inhibitor treatment did not inhibit induction of the PAI-1 gene (SERPINE1) in these cells. BaP plus 1,25(OH)2D3 induced differentiation markers, inhibited cellular proliferation, and induced apoptosis and oxidative stress in these cells. Reactive oxygen species scavenger treatment suppressed apoptosis but not SERPINE1 induction in cells treated with BaP plus 1,25(OH)2D3. Thus, combined treatment with BaP and 1,25(OH)2D3 induced SERPINE1 mRNA expression in these cells through a mechanism that does not require de novo protein synthesis or reactive oxygen species production. These findings suggest that induction of the proinflammatory factor PAI-1 plays a role in BaP toxicity. Interestingly, PAI-1 knockdown decreased expression of the cell surface antigen CD14, a monocytic differentiation marker, in THP-1 cells treated with BaP plus 1,25(OH)2D3. PAI-1 induction may also be related to a function of monocytes/macrophages in response to xenobiotic and vitamin D signaling.

Decision Analysis of Postremission Therapy in Cytogenetically Intermediate-Risk Acute Myeloid Leukemia: The Impact of FLT3 Internal Tandem Duplication, Nucleophosmin, and CCAAT/Enhancer Binding Protein Alpha.

We performed a decision analysis comparing allogeneic hematopoietic cell transplantation (allo-HCT) versus chemotherapy in first complete remission for patients with cytogenetically intermediate-risk acute myeloid leukemia, depending on the presence or absence of FLT3-internal tandem duplication (ITD), nucleophosmin (NPM1), and CCAAT/enhancer binding protein alpha (CEBPA) mutations. Adjusted means of the patient-reported EQ-5D index were used as quality-of-life (QOL) estimates. In 332 patients for which FLT3-ITD status was available, FLT3-ITD was present in 60. In 272 patients without FLT3-ITD, NPM1 mutations were present in 83. CEBPA biallelic mutations were detected in 53 patients. For patients harboring FLT3-ITD, allo-HCT improved life expectancy (LE) (52 versus 32 months during 10-year observation) and QOL-adjusted life expectancy (QALE, 36 versus 21). Monte-Carlo simulation identified allo-HCT as the favored strategy in 100% of simulations. In patients without FLT3-ITD, allo-HCT improved LE/QALE with or without NPM1 mutations. However, sensitivity analyses showed that the results were not robust enough. For patients harboring CEBPA biallelic mutations, chemotherapy was favored (LE, 53 versus 84; QALE, 37 versus 59), whereas, for patients with monoallelic mutations or wild-type CEBPA, allo-HCT was favored (LE, 68 versus 54; QALE, 48 versus 37). Sensitivity analyses did not change the results in either group. In conclusion, based on a Markov decision analysis, allo-HCT was a favored postremission strategy in patients with FLT3-ITD, and chemotherapy was favored in patients with biallelic CEBPA mutations. A prospective study is warranted to determine the value of allo-HCT, especially in FLT3-ITD-negative patients.

Clinical usefulness of WT1 mRNA expression in bone marrow detected by a new WT1 mRNA assay kit for monitoring acute myeloid leukemia: a comparison with expression of WT1 mRNA in peripheral blood.

We have previously shown the clinical usefulness of Wilms' tumor 1 gene (WT1) mRNA expression in peripheral blood (PB) as a minimal residual disease (MRD) monitoring marker in 191 acute myeloid leukemia (AML) patients using the WT1 mRNA assay kit "Otsuka" (Otsuka Pharmaceutical Co., Ltd.; "former kit"). In contrast, the usefulness of WT1 mRNA expression in bone marrow (BM) has been investigated in only a limited number of subjects using former kit. Following that previous study, a next-generation kit, WT1 mRNA assay kit II "Otsuka" (Otsuka Pharmaceutical Co., Ltd.; "new kit") has been newly developed. In the present study, we aimed to evaluate the performance of the new kit and to investigate the clinical usefulness of WT1 mRNA expression in BM. The PB and BM were collected on the same day from 164 blood disease patients, including 118 AML patients. WT1 mRNA expression was determined using the new and former kits and the values obtained were compared. The performance of new kit was shown to be equivalent to that of former kit. As reported in PB, WT1 mRNA expression in BM was found to be a useful marker for monitoring disease status as well as for a diagnosis of early stage relapse in AML patients.

Identification of a novel E-box binding pyrrole-imidazole polyamide inhibiting MYC-driven cell proliferation.

The MYC transcription factor plays a crucial role in the regulation of cell cycle progression, apoptosis, angiogenesis, and cellular transformation. Due to its oncogenic activities and overexpression in a majority of human cancers, it is an interesting target for novel drug therapies. MYC binding to the E-box (5'-CACGTGT-3') sequence at gene promoters contributes to more than 4000 MYC-dependent transcripts. Owing to its importance in MYC regulation, we designed a novel sequence-specific DNA-binding pyrrole-imidazole (PI) polyamide, Myc-5, that recognizes the E-box consensus sequence. Bioinformatics analysis revealed that the Myc-5 binding sequence appeared in 5'- MYC binding E-box sequences at the eIF4G1, CCND1, and CDK4 gene promoters. Furthermore, ChIP coupled with detection by quantitative PCR indicated that Myc-5 has the ability to inhibit MYC binding at the target gene promoters and thus cause downregulation at the mRNA level and protein expression of its target genes in human Burkitt's lymphoma model cell line, P493.6, carrying an inducible MYC repression system and the K562 (human chronic myelogenous leukemia) cell line. Single i.v. injection of Myc-5 at 7.5 mg/kg dose caused significant tumor growth inhibition in a MYC-dependent tumor xenograft model without evidence of toxicity. We report here a compelling rationale for the identification of a PI polyamide that inhibits a part of E-box-mediated MYC downstream gene expression and is a model for showing that phenotype-associated MYC downstream gene targets consequently inhibit MYC-dependent tumor growth.

Marked improvement of Churg-Strauss syndrome neuropathy by intravenous immunoglobulin and cyclophosphamide.

A 42-year-old Japanese man developed Churg-Strauss syndrome 7 years after being diagnosed with chronic eosinophilic pneumonia. Prominent eosinophilia, subcutaneous nodules, and neuropathy in the left leg were seen. A pathological diagnosis of necrotizing vasculitis was determined by a biopsy of a subcutaneous nodule. The leg pain was severe and there was prominent atrophy of the thigh and calf, but the muscle weakness was mild. Serum anti-myeloperoxidase anti-neutrophil cytoplasmic antibody was positive. Because the initial treatment with an intravenous methylprednisolone pulse at 1 g/day for 3 days was not sufficient, a onetime treatment with intravenous cyclophosphamide at 15 mg/kg and intravenous immunoglobulin therapy (IVIG) at 400 mg/kg/day for 5 days were administered. Peripheral eosinophilia improved and the leg pain significantly improved. IVIG was repeated 1 month later and symptoms gradually improved further. The early diagnosis of Churg-Strauss syndrome and the early initiation of IVIG with cyclophosphamide were thought to be important.

Efficacy of molecular response at 1 or 3 months after the initiation of dasatinib treatment can predict an improved response to dasatinib in imatinib-resistant or imatinib-intolerant Japanese patients with chronic myelogenous leukemia during the chronic phase.

Dasatinib is a BCR-ABL kinase inhibitor with improved potency compared with imatinib, for which efficacy and safety in imatinib-resistant and imatinib-intolerant patients with chronic myelogenous leukemia (CML) have been established. Here, an open-label phase II study evaluated the efficacy and safety of dasatinib in 50 Japanese patients with imatinib-resistant or imatinib-intolerant CML during the chronic phase (CML-CP). Dasatinib was effective in imatinib-resistant and imatinib-intolerant patients. After 12 months of dasatinib therapy, 35 patients (70%) had achieved a major molecular response (MMR) and 16 patients (32%) had achieved a complete molecular response (CMR). Among the imatinib-resistant CML-CP cohort, 21 and 8 patients had achieved an MMR and a CMR after 12 months of dasatinib therapy, respectively. Among the imatinib-intolerant CML-CP cohort, 14 and 8 patients had achieved an MMR and a CMR after 12 months of dasatinib therapy, respectively. After 18 months of dasatinib therapy, 38 out of 50 patients (76.0%) had achieved an MMR and 19 patients (38.0%) had achieved a CMR. A lower level of BCR-ABL transcript at 1 or 3 months after the initiation of dasatinib treatment was more strongly correlated with the BCR-ABL transcript level at 12 and 18 months (p ＜ 0.001) than a higher level of BCR-ABL. The T315I mutation was identified in two patients receiving dasatinib therapy. Dasatinib was generally well tolerated, with only 3 patients (5%) having treatment discontinuation as a result of adverse hematologic events (thrombocytopenia, anemia, neutropenia) and/or non-hematologic events at a 12-month follow-up evaluation. Dasatinib was a safe and effective treatment for Japanese patients with imatinib-resistant or imatinib-intolerant CML. In addition, the molecular response at 1 or 3 months predicted a response to dasatinib at 12 or 18 months.

Induced differentiation of human myeloid leukemia cells into M2 macrophages by combined treatment with retinoic acid and 1α,25-dihydroxyvitamin D3.

Retinoids and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) induce differentiation of myeloid leukemia cells into granulocyte and macrophage lineages, respectively. All-trans retinoic acid (ATRA), which is effective in the treatment of acute promyelocytic leukemia, can induce differentiation of other types of myeloid leukemia cells, and combined treatment with retinoid and 1,25(OH)2D3 effectively enhances the differentiation of leukemia cells into macrophage-like cells. Recent work has classified macrophages into M1 and M2 types. In this study, we investigated the effect of combined treatment with retinoid and 1,25(OH)2D3 on differentiation of myeloid leukemia THP-1 and HL60 cells. 9-cis Retinoic acid (9cRA) plus 1,25(OH)2D3 inhibited proliferation of THP-1 and HL60 cells and increased myeloid differentiation markers including nitroblue tetrazolium reducing activity and expression of CD14 and CD11b. ATRA and the synthetic retinoic acid receptor agonist Am80 exhibited similar effects in combination with 1,25(OH)2D3 but less effectively than 9cRA, while the retinoid X receptor agonist HX630 was not effective. 9cRA plus 1,25(OH)2D3 effectively increased expression of M2 macrophage marker genes, such as CD163, ARG1 and IL10, increased surface CD163 expression, and induced interleukin-10 secretion in myeloid leukemia cells, while 9cRA alone had weaker effects on these phenotypes and 1,25(OH)2D3 was not effective. Taken together, our results demonstrate selective induction of M2 macrophage markers in human myeloid leukemia cells by combined treatment with 9cRA and 1,25(OH)2D3.

Safety and efficacy of high-dose cyclophosphamide, etoposide and ranimustine regimen followed by autologous peripheral blood stem cell transplant for patients with diffuse large B-cell lymphoma.

We retrospectively evaluated the safety and efficacy of high-dose chemotherapy consisting of cyclophosphamide, etoposide and ranimustine (CEM) with autologous peripheral blood stem cell transplant (PBSCT) in 55 adult patients with relapsed or high-risk de novo diffuse large B-cell lymphoma (DLBCL) or DLBCL associated with follicular lymphoma. This included 36 patients in the upfront setting in their first complete remission. The median follow-up of 42 patients surviving at the time of the analysis was 52 months (range 1-159). Relapse or disease progression after PBSCT was a frequent cause of death, but no therapy-related mortality associated with PBSCT was observed. The 5-year overall survival and progression-free survival were 70.6% (95% confidence interval [CI], 54.0-82.1) and 57.0% (95% CI, 39.5-71.2), respectively. Chronic renal impairment, therapy-related myelodysplastic syndrome and prostate cancer were the major late complications. The CEM regimen is a tolerable, effective conditioning regimen for autologous PBSCT for DLBCL, with no therapy-related mortality observed.

Enhancement of differentiation induction and upregulation of CCAAT/enhancer-binding proteins and PU.1 in NB4 cells treated with combination of ATRA and valproic acid.

The effects of all-trans retinoic acid (ATRA) and valproic acid (VPA), alone and in combination, on the human acute promyelocytic leukemia (APL) cell line NB4 were investigated in view of differentiation induction and growth inhibition. After 48 h of treatment, not only ATRA but also VPA induced differentiation in NB4 cells, and their combination further augmented the differentiation activity. Furthermore, the upregulation of transcription factors including CCAAT/enhancer-binding proteins (CEBPα, ß, ε) and PU.1, which are known to be critical factors for normal myelopoiesis, granulocytic maturation and being repressed in APL, concurred with the differentiation induction. A significant cell growth inhibition was observed after the treatment with VPA, which was further strengthened by the addition of ATRA. Given the importance of C/EBPs and PU.1 in myeloid development, these results, thus, suggest that restoration of the normal function of the myeloid cell transcriptional machinery is a major molecular mechanism underlying the differentiation induction in NB4. Therefore, these results may provide novel insights into a possible combinational therapeutic approach for APL patients.

Relative increase in lymphocytes from as early as 1 month predicts improved response to dasatinib in chronic-phase chronic myelogenous leukemia.

Lymphocytosis in response to dasatinib for chronic myelogenous leukemia (CML) may be associated with favorable response. However, it occurs at varying times and in a limited subset of patients. To identify early clinical markers for favorable responses applicable to all patients with or without lymphocytosis, we prospectively analyzed lymphocyte profiles of 50 Japanese CML patients treated with dasatinib after intolerance/resistance to imatinib. Although absolute lymphocyte counts did not differ significantly until 3 months between patients with complete molecular response (CMR) at 12 months and those without it, relative increases in lymphocyte compared with baselines differed significantly from 1 month. Patients with relative lymphocyte counts >150 % at 1 month or >200 % at 3 months had higher CMR rates at 12 months than others (57.9 vs. 23.3 %, P = 0.015, and 76.5 vs. 16.1 %, P < 0.0001, respectively). A relative increase in lymphocyte subset of CD57(+)CD14(-), CD8(+)T, or NK cells >200 % at 1 month was also significantly associated with a higher CMR rate. There were significant negative correlations between relative lymphocyte increases and BCR/ABL transcript levels. CD57(+)CD14(-) cells were a highly specific focus of proliferation. Relative increases in lymphocyte count and its subsets from 1 month are reliable early markers of favorable responses to dasatinib.

Efficacy of oral cytarabine ocfosfate and etoposide in the treatment of elderly patients with higher-risk myelodysplastic syndromes compared to that in elderly acute myeloid leukemia patients.

BACKGROUND: Elderly acute myeloid leukemia (AML) patients and patients with higher-risk myelodysplastic syndromes (MDS) have a much poorer prognosis than younger patients despite intensive chemotherapy. METHODS: Ten patients with higher-risk MDS and 12 patients with AML over 65 years of age were enrolled into this study and received oral induction therapy with cytarabine ocfosfate and etoposide. RESULTS: The therapy response rates were 60% in the MDS group and 41.7% in the AML group. The difference in overall survival among MDS and AML patients was not statistically significant. The difference in the median survival times of the responsive and nonresponsive groups, which included MDS and AML patients, was statistically significant (790 and 174 days, respectively). CONCLUSIONS: Based on a comparison of the data of this therapy in elderly higher-risk MDS patients versus elderly AML patients, we conclude that this therapy is well tolerated and can be cost-effective and useful for higher-risk MDS in elderly patients.

CD56 expression is an independent prognostic factor for relapse in acute myeloid leukemia with t(8;21).

We investigated the significance of surface antigen expression for prognosis by focusing on a specific subtype, AML with t(8;21). The investigation included 144 patients with AML with t(8;21) in the JALSG AML97 study. AML with t(8;21) expressed CD19 (36%), CD34 (96%), and CD56 (65%) more frequently than did other subtypes of AML. CD19 expression had a significant favorable effect on CR (95.7% vs. 83.8%; P=0.049). Univariate analysis showed that increased white blood cell (WBC) counts (WBC ≥ 20 × 10(9)/L), CD19 negativity, and CD56 positivity were critical adverse factors for relapse after CR; multivariate analysis revealed that WBC count and CD56 expression were independent adverse risk factors (HR 2.18; P=0.045, HR 2.30; P=0.011, respectively). We concluded that CD56 expression has a possible role in risk stratification for patients with AML with t(8;21).

The demarcation between younger and older acute myeloid leukemia patients: a pooled analysis of 3 prospective studies.

BACKGROUND: Contemporary treatment protocols for adult acute myeloid leukemia (AML) are age-specific, and older patients are generally treated less intensively than younger patients. However, it remains uncertain whether older but fit patients with AML really need to have their treatment attenuated. METHODS: To evaluate the contribution of age to outcome for patients with AML receiving intensive chemotherapy, data were analyzed for 2276 patients aged less than 65 years who were treated uniformly, regardless of age, in 3 consecutive prospective studies conducted by the Japan Adult Leukemia Study Group. RESULTS: A substantial drop in overall survival (OS) between patients aged 40 to 49 years and 50 to 64 years led to a focus on 2 comparisons: 1) age < 50 versus ≥ 50 years; and 2) age 50 to 54 versus 55 to 59 versus 60 to 64 years. OS was significantly better for patients aged < 50 years than that for those aged ≥ 50 years (49.6% and 37.0% at 5 years; P < .001); older patients were more susceptible to relapse, but not to early death or nonrelapse mortality. The significant differences in OS between these 2 age groups were equally seen for patients with favorable, intermediate, and adverse cytogenetics (P < .001 each). Outcomes for those aged 50 to 54, 55 to 59, and 60 to 64 years were similar, with 5-year OS rates of 38.2%, 35.1%, and 38.0%, respectively (P = .934), and no differences in early death or nonrelapse mortality were observed among these age groups. CONCLUSIONS: These findings justify the use of intensive chemotherapy without dose attenuation toward older but fit patients with AML, at least up to the age of 64 years.

Prognosis of patients with core binding factor acute myeloid leukemia after first relapse.

Core binding factor acute myeloid leukemia is known to have a favorable prognosis, however, there have been no detailed analyses on prognostic factors after first relapse. Using a nationwide database, we retrospectively analyzed core binding factor acute myeloid leukemia patients who relapsed after being treated with chemotherapy alone during their first complete remission. Of a total of 397 patients who were diagnosed with core binding factor acute myeloid leukemia, 208 experienced a first relapse, and analyses were performed in 139 patients for whom additional data were available. In the entire cohort, the overall survival rate after relapse was 48% at 3 years. By multivariate analysis, younger age at diagnosis, a longer interval before relapse, and inv(16) were shown to be independently associated with better survival after relapse. Although there was no significant difference in survival after relapse between patients who underwent allogeneic hematopoietic cell transplantation and those who did not in the overall series of relapsed patients, we found that transplantation significantly improved survival among patients who had t(8;21) (54% versus 26% at 3 years, P=0.002). In addition, among patients with t(8;21), those who had different cytogenetics at relapse had a significantly improved survival after transplantation, while those who had same cytogenetics did not. We showed that the prognosis differs significantly and optimal treatment strategies may vary between groups of patients with core binding factor acute myeloid leukemia with different cytogenetic profiles at relapse. These findings may help to guide therapeutic decisions after first relapse.

Aquaporin 9, a promising predictor for the cytocidal effects of arsenic trioxide in acute promyelocytic leukemia cell lines and primary blasts.

A close correlation between the cytocidal effects of arsenic trioxide (ATO) and aquaporin-9 (AQP9) expression levels has been proposed, yet detailed studies are still needed to confirm this association. Thus, in the present study, the correlation between the expression levels of AQP9 and sensitivity to ATO was investigated using two acute promyelocytic leukemia (APL) cell lines, NB4 and HT93A, as well as primary APL cells from newly diagnosed and relapsed APL patients. A substantially higher sensitivity to ATO-mediated induction of apoptosis was observed in the NB4 cells when compared to that in the HT93A cells. In addition, markedly higher expression levels of AQP9, as assessed using flow cytometry, along with more intracellular arsenic accumulation, were observed in the NB4 cells. More importantly, similar to APL cell lines, the trend of expression levels of AQP9 correlated closely with the differential sensitivity to ATO-mediated induction of apoptosis in primary APL cells. In contrast, no correlation was observed between ATO sensitivity associated with AQP9 expression levels and the expression profiles of cell surface markers as well as chromosomal alterations. These results provide direct evidence that the expression levels of AQP9, rather than other biomarkers such as cell surface markers and chromosomal alterations, correlate closely with the sensitivity to ATO in both APL cell lines and primary blasts. These findings suggest that the AQP9 expression status of APL patients is a predictive marker for the successful outcome of ATO treatment, since AQP9 plays a pivotal role in various arsenite-mediated biological effects on normal and cancer cells. Moreover, flow cytometry may be a new convenient and valuable tool for analyzing the AQP9 status of APL patients compared to current methods such as western blotting.

Diagnostic value of open biopsy for malignant T-cell lymphoma of the liver.

A 62-year-old man was referred to our hospital because of pain in the right upper quadrant. Laboratory tests revealed normal levels of tumor markers. Abdominal ultrasonography showed a hypoechoic mass of approximately 9 cm in diameter in the right lobe of the liver. Computed tomography revealed a low-density mass with peripheral enhancement in the posterior segment of the right lobe. Magnetic resonance imaging showed a low-intensity mass on T(1)-weighted images and a high-intensity mass on T(2)-weighted images. Abdominal angiography showed enhanced staining only at the periphery of the tumor. An open biopsy was performed and intraoperative examination of frozen sections indicated malignant lymphoma. The histopathologic diagnosis was malignant T-cell lymphoma. After combined chemotherapy, the tumor shrank to 4 cm in diameter. To our knowledge, only 15 cases of malignant T-cell lymphoma have been reported previously. Diagnosis is particularly challenging because this type of tumor has no distinctive imaging characteristics or signs or symptoms. This case emphasizes the need to include malignant T-cell lymphoma in the differential diagnosis and demonstrates the importance of open biopsy in patients with a suspected liver tumor.