A case of splenomegaly with RK-39 positivity: A diagnostic pitfall

Long-standing moderate to marked splenomegaly suggests several differential diagnoses, both haematological and infectious, particularly leishmaniasis and malaria in endemic areas. Non-infectious causes may be missed in these regions, especially if pitfalls of serological testing are not considered. Careful patient evaluation is necessary to arrive at the correct diagnosis. We report a case of a young male whose hereditary spherocytosis was initially missed because of RK-39 positivity, splenomegaly and the fact that he hailed from an endemic region.

Reduced Tet2 Function Contributes to Development of Peripheral T-Cell Lymphoma with Follicular Helper T-Cell-Like Features in Mice

Abstract 1299 Background: Loss-of-function mutations in TET2 are frequent in human myeloid and lymphoid malignancies. Especially, TET2 mutations were found in 30–47% of angioimmunoblastic T-cell lymphoma (AITL) and 10–38% of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS). The tumor origin of AITL is thought to be follicular helper T cells (Tfh). PTCL, NOS is a group of heterogenous T-cell-derived lymphomas, whereas some cases of PTCL, NOS also appear to be derived from Tfh. Several recent papers reported that Tet2 knockout mice demonstrated premalignant status of myeloid lineages, implicating that TET2 mutations have a driver's role in myeloid malignancies; however, there are no clues to how impaired Tet2 function provokes T-cell lymphomas. To address this issue, we analyzed Tet2 gene trap (Tet2gt) mice. Materials and methods: Tet2gt mice (Transgenic Res 17:599, 2008) have a trapping vector inserted into the second intron of Tet2 locus. Lineage-, Sca1+, and c-kit+ (LSK) cells were sorted from Tet2gt E15.5 fetal liver (FL) cells and transplanted into lethally irradiated Ly5.1 wild-type (WT) mice. Bone marrow, spleen, and tumors when developed were analyzed in the recipient mice as well as adult Tet2gtmice by flow cytometory and immunohistochemical staining. Result: Adult Tet2gt mice were obtained under the following ratio; Tet2+/+:Tet2+/gt:Tet2gt/gt=48:52:25. TET2 mRNA expression level in Tet2gt/gt Lin- FL cells was reduced to 20% of that in WT Lin- FL cells, while the 5-hydroxymethyl cytosine level was reduced to around a half of that in WT cells. At 40 weeks of age, the proportion of CD4+/PD1+/Cxcr5+ cells, immunophenotypically similar to Tfh cells, significantly increased in Tet2gt/gt mice compared to WT mice (P=0.022). Two out of 8 Tet2gt/gt mice developed marked splenomegaly (more than 300 mg) at 40 weeks, and 4 out of 6 developed marked splenomegaly with swollen lymph nodes and multi-nodular tumors in liver and lungs at 60 weeks or older (median, 67 weeks). Histological examination of the enlarged spleen and swollen lymph nodes in these 4 mice demonstrated completely destroyed follicular structures. The spleen, lymph nodes, and nodular tumors showed infiltration of morphologically abnormal lymphocytes, which were proven to be CD4+/PD1+ T cells. These cells were also weakly positive for Cxcr5. CD4+ cells purified from the tumors revealed restricted rearrangement patterns of T-cell receptor genes, implying T-cell lymphoma. There were no increased vascular structures representing AITL. CD4+/PD1+ cells purified from the tumors expressed Bcl6 and cMaf, two key transcription factors of Tfh, at significantly higher levels compared to CD4+/PD1+ cells purified from spleen of WT mice. Meanwhile, one of 6 mice transplanted with Tet2gt/gt LSK cells also developed lymphoma with similar pattern of CD4+/PD1+/CXCR5 expression at 40 weeks after transplantation. Discussion: Our observations indicate that reduced expression of TET2 may cause skewed differentiation into Tfh, which eventually develop tumors that pathologically recapitulate PTCL, NOS in human, while the tumor-comprising cells show characteristics of Tfh. The long latency period required for tumor development indicates secondary genetic hits in addition to the downregulation of TET2. These secondary events might determine the specificity of the hematologic malignancies, particularly AITL and PCTL, NOS with propensity for AITL. Disclosures: No relevant conflicts of interest to declare.

A Phase-2 Trial of Low-Dose Pomalidomide In Myelofibrosis with Anemia

Abstract 4109 Background: In a previous study, we reported safety and efficacy of low-dose (0.5 mg/d) pomalidomide and prednisone and pomalidomide alone (2 mg/d) for the treatment of anemia associated with myelofibrosis (J Clin Oncol 2009; 27: 4563). The current study examined the value of low dose pomalidomide alone (ClinicalTrials.gov No. NCT00669578). Methods: Persons with primary (PMF) or post-polycythemia vera/essential thrombocythemia (post-PV/ET MF) myelofibrosis were studied. The main eligibility criterion was RBC-transfusion-dependence or hemoglobin <10 g/dL. Subjects failing lenalidomide or thalidomide were eligible whereas those with deep vein thrombosis or pulmonary-embolism <1 y pre-study entry were not. The primary endpoint was anemia response assessed by the International Working Group for Myeloproliferative Neoplasms Research and Treatment criteria (Blood 2006; 108: 1497). Results: Pomalidomide (0.5 mg/d) was given to 58 subjects (median age 68 y; 44 males). 46 (79%) were RBC-transfusion-dependent and 42, JAK2V617F-positive. Baseline disease-stage at time of study-entry according to the Dynamic International Prognostic Scoring System (DIPSS; Blood 2010; 115: 1703) was high-risk in 16 (28%) and intermediate-2 risk in 42 (72%). Cytogenetic findings were favorable in 46, unfavorable in 9 and not evaluable in 3. 46 (79%) had PMF and the remainder post-PV/ET MF. 49 (84%) patients completed ≥3 mo of therapy. Treatment was well-tolerated with no instances of thrombosis. There was grade-1 neuropathy possibly related to drug in 1 subject. ≥Grade-3 thrombocytopenia/neutropenia occurred in 2 subjects. There was an anemia response in 10 (17%) subjects including 9 who became RBC-transfusion-independent. Median response-duration was 8+ mo (range, 6–13 mo). 14 of 24 subjecst (58%) with platelets ≤100 × 10e9/L had a >50% increment. There were no spleen responses. Anemia response occurred only in subjects with JAK2V617F (24% vs. 0; p=0.03) but was not correlated with mutant allele burden (p=0.39). Anemia response in JAK2V617F-positive subjects was predicted by the presence of pomalidomide-induced basophilia in the 1st month of therapy (38% vs. 6%; p=0.02) or absence of marked splenomegaly (38% vs. 11%; p=0.05); response was not affected by cytogenetic risk-category (p=0.96) or WBC (p=0.27). Conclusions: These data suggest that low-dose pomalidomide is effective in the treatment for anemia associated with JAK2V617F-positive myelofibrosis, especially in the absence of marked splenomegaly. Response appears to be predicted by early drug-induced basophilia. Pomalidomide also appears to improve thrombocytopenia in most subjects with baseline platelets <100 × 10e9/L but is not active in controlling disease-associated splenomegaly. Disclosures: Mesa: SBio: Research Funding; Novartis: Research Funding; Celgene: Research Funding; Incyte: Research Funding; Roche: Research Funding; eisai: Research Funding; telik: Research Funding.

Hydroxyurea Effect On Marked Splenomegaly Associated with Primary Myelofibrosis: Response Rates and Correlation with JAK2V617F Allele Burden.

Abstract 4971 Background Marked splenomegaly severely compromises quality of life in primary myelofibrosis (PMF). Preliminary results from the use of small molecule JAK2 inhibitors suggest prominent activity in reducing spleen size. In order to put such salutary effect of investigational drug therapy in context, it is important to determine the value of conventional therapy in this regard. Methods Study population was selected from the Mayo Clinic PMF database and consisted of patients treated with hydroxyurea (HU) as first-line therapy for symptomatic, marked splenomegaly (palpable at >10 cm below the left costal margin) and in whom follow-up information was available to assess response. Palpable spleen size measurements were recorded before and after 3, 6 and 12 months of HU therapy. Spleen response was defined as minimal (< 25% reduction), minor (25-50%), or major (>50%). Standard statistical procedures were used to correlate spleen response with other clinical and laboratory parameters, including cytogenetic and JAK2V617F mutational status. Results 46 consecutive patients (median age, 62 years; range 38-75; 30 males) met the above stipulated eligibility criteria for study inclusion. Pre-treatment IPSS risk categories were low, intermediate-1 (int-1), int-2 and high in 4, 13, 10 and 19 patients, respectively; 7 patients were transfusion-dependent. Quantitative JAK2V617F and pre-treatment cytogenetic information were available in 25 and 36 patients, respectively; 15 (60%) patients were positive for JAK2V617F and mutant allele burden was > 50% in 6 patients; 17 (47%) patients carried either favorable (n=5) or unfavorable (n=12) cytogenetic abnormalities. Overall response rate (major and minor) was 35% (16 of 46 patients) and major response rate 17%. Overall response rates were 10%, 67% and 33% in patients with undetectable JAK2V617F or mutant allele burden of < or ≥ 50%, respectively (p=0.04). Overall response rates in patients with normal, favorable and unfavorable karyotype were 32%, 40% and 33%, respectively (p=0.9). Response was not affected by age, sex, HU dose or pretreatment status regarding spleen size, IPSS score or transfusion need. Conclusions The current study provides background information on the value of conventional chemotherapy for controlling PMF-associated marked splenomegaly. The study also suggests a positive effect of JAK2V617F on treatment response to HU, a detail that needs to be considered when assessing the corresponding effect from a JAK2 inhibitor therapy. Disclosures Off Label Use: Hydroxyurea use in myelofibrosis.

Chlorambucil Induced Angioedema of the Tongue in a Patient with Lymphoma.

A Caucasian female, born in 1941, was first seen in November 2002 because of tiredness, weight loss and splenomegaly. She was taking glyburide, procylidine and venlafaxine for diabetes, parkinsonism and depression. Physical examination, revealed marked splenomegaly but no lymphadenopathy. Flowcytometry of peripheral blood showed a monoclonal B cell lymphoproliferative disorder consistent with marginal zone lymphoma. She was treated with chlorambucil 6 mg daily and prednisone 25 mg daily. She responded well to therapy. Chemotherapy was discontinued in December 2003. In April 2005 she was admitted to the hospital with pneumonia. She had pancytopenia and marked splenomegaly. Bone marrow apirate showed infiltration with marginal zone lymphoma cells. She was prescribed Chlorambucil 6 mg daily for management of her recurrent lymphoma. She took her first 6 mg of Chlorambucil at 8:00 PM of May 18, 2005 and woke up around 5:30 AM with grossly swollen tongue. She was brough to Emergency ward at 06:45 hr with grossly swollen, tender tongue protrudinng form her widely opened mouth. Angioedema of the tongue was diagnosed and she was given epinephrin, IV Benadryl, Solumedrol and morphine. By 10:00 hr, she was in moderate respiratory distress. She was taken to OR at 10:20 for urgent intubation or tracheotomy. Endoscopy revealed ++ oropharyngeal and supraglotic edema. A nasotracheal tube was inserted at 11:00 hr. The picture included was taken one hour after intubation.(16 hrs after taking chlorambucil). She was given Solumedrol 125 mg IV Q 12 hr. By 24 hours after intubation her tongue had receded into her mouth and she was extubated. Her serum C1 inhibitor was 0.13 g/L (normal 0.15–0.35) and functional C1 esterase inhibitor was 87% (normal &gt;67%). Immunoglobulines, C3 & C4 were normal. Her lymphoma was treated with 6 courses of R-CVP regimen. She has not received any more chlorambucil and she has not had any more angioedema or anaphylactic reaction of any kind. In May 2005 her C1 inhibitor was 0.38 g/L and functional C1 esterase inhibitor was 96%. Discussion: on the day before experiencing angioedema of the tongue, she had not taken any unusual food or any other new medication. The time sequence and subsequent course of this case strongly suggest that the angioedema of the tongue was due to Chlorambucil. The literature does not show any report of chlorambucil induced angioedema. However, angioedema is listed as one of the adverse reactions of Chlorambuci both in AHFS Drug Information and in Compendium of Pharmaceuticals and Specialities. Following communication with GlaskoSmithKline, the manufacturer of Chlorambucil, I was told that, they are not aware of any published report, but they have reports of angioedema induced by Chlorambucil in their file. I was told that they are not in position to reveal the number of such reactions. Figure Figure