Recurrent translocations involving the IRF4 oncogene locus in peripheral T-cell lymphomas.

Oncogenes involved in recurrent chromosomal translocations serve as diagnostic markers and therapeutic targets in hematopoietic tumors. In contrast to myeloid and B-cell neoplasms, translocations in peripheral T-cell lymphomas (PTCLs) are poorly understood. Here, we identified recurrent translocations involving the multiple myeloma oncogene-1/interferon regulatory factor-4 (IRF4) locus in PTCLs. IRF4 translocations exist in myeloma and some B-cell lymphomas, but have not been reported earlier in PTCLs. We studied 169 PTCLs using fluorescence in situ hybridization and identified 12 cases with IRF4 translocations. Two cases with t(6;14)(p25;q11.2) had translocations between IRF4 and the T-cell receptor-alpha (TCRA) locus. Both were cytotoxic PTCLs, unspecified (PTCL-Us) involving bone marrow and skin. In total, 8 of the remaining 10 cases were cutaneous anaplastic large-cell lymphomas (ALCLs) without TCRA rearrangements (57% of cutaneous ALCLs tested). These findings identified IRF4 translocations as a novel recurrent genetic abnormality in PTCLs. Cytotoxic PTCL-Us involving bone marrow and skin and containing IRF4/TCRA translocations might represent a distinct clinicopathologic entity. Translocations involving IRF4 but not TCRA appear to occur predominantly in cutaneous ALCLs. Detecting these translocations may be useful in lymphoma diagnosis. Further, due to its involvement in translocations, MUM1/IRF4 protein may play an important biologic role in some PTCLs, and might represent a possible therapeutic target.

Overexpression of Syk tyrosine kinase in peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCLs) are fatal in the majority of patients and novel treatments, such as protein tyrosine kinase (PTK) inhibition, are needed. The recent finding of SYK/ITK translocations in rare PTCLs led us to examine the expression of Syk PTK in 141 PTCLs. Syk was positive by immunohistochemistry (IHC) in 133 PTCLs (94%), whereas normal T cells were negative. Western blot on frozen tissue (n=6) and flow cytometry on cell suspensions (n=4) correlated with IHC results in paraffin. Additionally, western blot demonstrated that Syk-positive PTCLs show tyrosine (525/526) phosphorylation, known to be required for Syk activation. Fluorescence in situ hybridization showed no SYK/ITK translocation in 86 cases. Overexpression of Syk, phosphorylation of its Y525/526 residues and the availability of orally available Syk inhibitors suggest that Syk merits further evaluation as a candidate target for pharmacologic PTK inhibition in patients with PTCL.

Splenic marginal zone lymphoma proposals for a revision of diagnostic, staging and therapeutic criteria.

Since the initial description of splenic marginal zone lymphoma (SMZL) in 1992, an increasing number of publications have dealt with multiple aspects of SMZL diagnosis, molecular pathogenesis and treatment. This process has identified multiple inconsistencies in the diagnostic criteria and lack of clear guidelines for the staging and treatment. The authors of this review have held several meetings and exchanged series of cases with the objective of agreeing on the main diagnostic, staging and therapeutic guidelines for patients with this condition. Specific working groups were created for diagnostic criteria, immunophenotype, staging and treatment. As results of this work, guidelines are proposed for diagnosis, differential diagnosis, staging, prognostic factors, treatment and response criteria. The guidelines proposed here are intended to contribute to the standardization of the diagnosis and treatment of these patients, and should facilitate the future development of clinical trials that could define more precisely predictive markers for histological progression or lack of response, and evaluate new drugs or treatments.

Novel FISH probes designed to detect IGK-MYC and IGL-MYC rearrangements in B-cell lineage malignancy identify a new breakpoint cluster region designated BVR2.

Detection of translocations involving MYC at 8q24.1 in B-cell lineage malignancies (BCL) is important for diagnostic and prognostic purposes. However, routine detection of MYC translocations is often hampered by the wide variation in breakpoint location within the MYC region, particularly when a gene other than IGH, such as IGK or IGL, is involved. To address this issue, we developed and validated four fluorescence in situ hybridization (FISH) probes: two break apart probes to detect IGK and IGL translocations, and two dual-color, dual-fusion FISH (D-FISH) probes to detect IGK-MYC and IGL-MYC. MYC rearrangements (four IGK-MYC, 12 IGL-MYC and four unknown partner gene-MYC) were correctly identified in 20 of 20 archival BCL specimens known to have MYC rearrangements not involving IGH. Seven specimens, all of which lacked MYC rearrangements using a commercial IGH/MYC D-FISH probe, were found to have 8q24 breakpoints within a cluster region >350-645 kb 3' from MYC, provisionally designated as Burkitt variant rearrangement region 2 (BVR2). FISH is a useful ancillary tool in identifying MYC rearrangements. In light of the discovery of the distally located BVR2 breakpoint cluster region, it is important to use MYC FISH probes that cover a breakpoint region at least 1.0 Mb 3' of MYC.

Interphase fluorescence in situ hybridization with an IGH probe is important in the evaluation of patients with a clinical diagnosis of chronic lymphocytic leukaemia.

Translocations involving IGH are common in some lymphoid malignancies but are believed to be rare in chronic lymphocytic leukaemia (CLL). To study the clinical utility of fluorescence in situ hybridization (FISH) for IGH translocations, we reviewed 1032 patients with a presumptive diagnosis of CLL. Seventy-six (7%) patients had IGH translocations. Pathology and clinical data were available for the 24 patients evaluated at the Mayo Clinic. Ten (42%) patients had IGH/cyclin D1 fusion and were diagnosed with mantle cell lymphoma (MCL). The immunophenotype was typical of MCL in three of these patients and atypical for MCL in seven patients. One patient had biclonal disease with typical MCL and CLL with IGH/BCL-2. Eleven (46%) patients had IGH/BCL-2 fusion including the patient with biclonal disease. Two of these patients had leukaemic phase follicular lymphoma and nine patients had CLL. The median progression-free survival of patients with CLL and IGH/BCL-2 translocation was 20.6 months. The two patients with IGH/BCL-3 fusion (one of these also had IGH/BCL-11a) had rapid disease progression. The IGH partner gene was not identified in two patients. We conclude that use of an IGH probe in FISH analysis of monoclonal B-cell lymphocytosis improves diagnostic precision and could have prognostic value in patients with CLL.

Inhibition of survivin expression suppresses the growth of aggressive non-Hodgkin's lymphoma.

Survivin is a member of the inhibitor of apoptosis protein (IAP) family and functions both as an apoptosis inhibitor and a regulator of cell division. Survivin overexpression is common in many human tumors and correlates with survival in large cell non-Hodgkin's lymphoma. To evaluate this molecule as a potential therapeutic target in large-cell lymphoma, we evaluated the effect of survivin inhibition both in vitro and in vivo. Using an antisense oligonucleotide (ASO) approach, cell growth was significantly inhibited in the DoHH2, RL and HT lymphoma cell lines. In a lymphoma xenograft model, the development of tumors as well as the growth of established tumors was inhibited in the survivin ASO-treated mice compared to controls. To assess the efficacy of the survivin ASO in combination with other biological agents, we combined the survivin ASO with an anti-CD20 monoclonal antibody, rituximab. The effect of survivin ASO and rituximab in combination was additive in vitro. In vivo, however, suppression of tumor growth with the combination was not significantly superior to controls. We conclude that inhibition of survivin expression is an attractive therapeutic strategy in aggressive non-Hodgkin's lymphomas, and that combining survivin ASO with rituximab may enhance the efficacy of this approach.

Primary pulmonary MALT lymphomas show frequent and heterogeneous cytogenetic abnormalities, including aneuploidy and translocations involving API2 and MALT1 and IGH and MALT1.

API2-MALT1 fusion and aneuploidy are common chromosomal abnormalities in MALT lymphoma. In studying their incidence and relationship in primary pulmonary MALT lymphomas, a translocation involving MALT1 and IGH was also identified. In all, 28 primary pulmonary MALT lymphomas were studied by fluorescence in situ hybridization using an API2-MALT1 probe and multiple centromeric probes, as well as IGH-BCL2, IGH-MALT1, and MALT1 breakapart probes in selected cases. Seven (25%) had API2-MALT1 fusion; all seven lacked aneuploidy except for two with trisomy 3 in a small clone. Three (11%) had IGH-MALT1 fusion; two also showed trisomy 3 and 12. A total of 11 (39%) had aneuploidy only, with trisomy 3 and 18 being the most common. Ectopic nuclear bcl-10 expression, which has been previously associated with API2-MALT1, was seen by immunohistochemistry in 86% of API2-MALT1 fusion-positive cases, one IGH-MALT1 fusion-positive case, two aneuploidy-only cases, and two normal cases. In primary pulmonary MALT lymphomas, cytogenetic abnormalities are common (75%) and heterogeneous, encompassing API2-MALT1 and IGH-MALT1, which are mutually exclusive, as well as aneuploidy, which may be present in the latter but is rare in the former. Ectopic nuclear bcl-10 expression is associated with API2-MALT1 but may also be seen in IGH-MALT1 fusion-positive, aneuploidy-only, and normal cases.

Diagnostic utility of fluorescence in situ hybridization in mantle-cell lymphoma.

Mantle-cell lymphoma (MCL) has a poorer prognosis than other small B-cell lymphomas, thus a definitive diagnosis is essential. The t(11;14)(q13;q32) associated with MCL juxtaposes portions of CCND1 (11q13) and IGH (14q32), resulting in over-expression of cyclin D1. In this study, a highly sensitive two-colour fluorescence in situ hybridization (FISH) method was developed to detect t(11;14)(q13;q32) in nuclei isolated from paraffin-embedded tissue. Twenty-three MCLs, 13 normal controls and nine small B-cell lymphomas other than MCL were studied by FISH. Each MCL had been previously investigated to detect genomic IGH-CCND1 fusion by polymerase chain reaction (PCR) using DNA extracted from frozen tissue. The IGH-CCND1 fusion detection rate in the MCLs was 96% by FISH compared with 35% by PCR. By FISH, one MCL and three small B-cell lymphomas other than MCL harboured abnormalities involving only IGH. Less than 1% of cells showed false-positive IGH-CCND1 fusion in normal specimens by FISH. Thus, this highly sensitive FISH assay is very useful in confirming the diagnosis of MCL, has wide applicability as it may be performed on both paraffin-embedded and fresh tissue, and may also facilitate detection of translocations involving these loci in tumours other than MCL.

Nonrhabdomyosarcoma soft tissue sarcomas in children. The Mayo Clinic experience.

Eighty-six children to 18 years of age were treated for nonrhabdomyosarcoma soft tissue sarcomas of the trunk and extremities. Synovial sarcoma (31), fibrosarcoma (13), malignant fibrous histiocytoma (11), epithelioid sarcoma (10), and clear cell sarcoma (7) were the most common diagnoses. Four patients presented with metastatic disease. A high percentage of patients presented after biopsy by the referring physician, although this could not be shown to affect outcome. Patients were treated with wide removal of the tumor when possible, with judicious use of adjuvant radiation, or with chemotherapy in selected cases. Mean followup was 11 years. Five- and 10-year survival was 92% and 84%, respectively. Tumors larger than 5 cm were associated with a worse prognosis. When compared with published data in adults, the prognosis of primary, localized nonrhabdomyosarcoma soft tissue sarcomas in children appears to be more favorable.

Incidence and subtype specificity of API2-MALT1 fusion translocations in extranodal, nodal, and splenic marginal zone lymphomas.

The t(11;18)(q21;q21) is thought to represent an important primary event in the development of marginal zone lymphomas, although an accurate estimation of the frequency and distribution of this genetic alteration among nodal, splenic, and extranodal marginal zone lymphoma types has yet to be determined. Recently, molecular genetic studies have shown that this translocation results in the fusion of the API2 gene on chromosome 11 and a novel gene termed MALT1 on chromosome 18. To investigate the incidence of API2-MALT1 fusion transcripts among marginal zone lymphomas and to determine possible marginal zone lymphoma subtype associations, we used reverse transcriptase-polymerase chain reaction to analyze RNAs extracted from frozen tissue samples of 99 marginal zone lymphomas. Fifty-seven involved diverse extranodal sites including 14 stomach, 11 lung, 7 orbit, 7 parotid, 5 thyroid, 5 lacrimal gland, 3 small intestine, 2 large intestine, 1 kidney, 1 paraspinal region and 1 skin. Twenty-one primary splenic and twenty-one primary nodal marginal zone lymphomas were also studied. API2-MALT1 fusion transcripts were detected in 12 of 57 extranodal marginal zone lymphomas (21%), but in none of the nodal or splenic cases. The cDNA sequences of the fusion transcripts were determined, revealing variation in the coding sequence fusion point for both API2 and MALT1. The findings suggest that t(11;18)(q21;q21) is restricted to extranodal marginal zone lymphomas and that these tumors have distinct genetic etiologies in comparison with their splenic and nodal counterparts.

Sclerosing extramedullary hematopoietic tumor in chronic myeloproliferative disorders.

Sclerosing extramedullary hematopoietic tumor (SEMHT) occasionally may arise in patients with chronic myeloproliferative disorders (CMPDs). Morphologically, these tumors may be mistaken for sarcomas or other neoplasms, especially if the clinical history is unknown. We analyzed four cases to identify features to aid in this differential diagnosis. Clinically, there were four men (mean age, 64.5 years), each with a history of CMPD. Grossly, the SEMHTs formed solitary renal or perirenal masses or multiple mesenteric or omental nodules. Morphologically, each SEMHT had a sclerotic to myxoid background with thick collagen strands and trapped fat. Atypical megakaryocytes, maturing granulocytic and erythroid precursors, and few to no blasts were identified in all cases. The megakaryocytes, granulocytic precursors, and erythroid precursors reacted strongly with antibodies to factor VIII, myeloperoxidase, and hemoglobin, respectively, in immunohistochemical studies performed in selected cases. SEMHT is a rare manifestation of CMPD that may be mistaken for a sarcoma, especially sclerosing liposarcoma, Hodgkin's disease, especially lymphocyte depletion type, or a myelolipoma. In a myxoid tumor with trapped fat and atypical cells, morphologic and immunohistochemical identification of maturing hematopoietic precursors helps distinguish SEMHT from sarcoma or Hodgkin's disease. The presence of sclerosis and atypical megakaryocytes helps distinguish SEMHT from myelolipoma.

Multiple cerebral infarctions from nonbacterial thrombotic endocarditis mimicking cerebral vasculitis.

Primary vasculitis of the central nervous system (PVCNS) is an uncommon disorder that can present with a variety of symptoms, making diagnosis and management difficult. We describe a case of cerebral infarction that occurred from nonbacterial thrombotic endocarditis (NBTE) and presented with clinical and radiologic imaging features that suggested PVCNS. The patient was a 58-year-old woman with left hemiparesis, aphasia, and episodic confusion. Magnetic resonance imaging of the brain demonstrated multifocal lesions consistent with infarction involving both cerebral hemispheres, and cerebral angiography showed changes consistent with vasculitis. Although brain biopsy findings were normal, the patient was treated for presumed vasculitis with cyclophosphamide and prednisone. Four months later respiratory failure secondary to polymicrobial pneumonia and adult respiratory distress syndrome developed, and she died. Autopsy revealed multiple infarcts in the heart, lungs, right kidney, spleen, and brain. Multiple thrombotic platelet-fibrin vegetations consistent with NBTE were found on all cardiac valves. Examination of the brain revealed no evidence of active or healed vasculitis. Cerebral angiography may show findings that suggest vasculitis, but it is not diagnostic, as several other conditions may cause similar changes. Nonbacterial thrombotic endocarditis may cause multiple cerebral infarctions and can be difficult to distinguish from vasculitis, as specific diagnostic tests for PVCNS are lacking.

Plexiform fibrohistiocytic tumor: clinicopathologic analysis of 22 cases.

Twenty-two cases of plexiform fibrohistiocytic tumor were reviewed to perform a clinicopathologic correlation with the behavior of the neoplastic entity. The tumor arises more frequently in children, adolescents, and young adults (mean age of presentation, 14.6 years), with strong female predilection (F:M, 6:1). It involves preferentially the upper extremity (64%), especially the fingers, hand, or wrist (45%). Most patients present with a small (average size, 2.5 cm; range, 0.5-8 cm) painless mass that slowly enlarges for months to years. All tumors involve subcutaneous adipose tissue, with extension into the dermis (19%), skeletal muscle (14%), or both (14%). Grossly, the tumors characteristically are poorly circumscribed and of firm consistency. Histologically, they are characterized by a plexiform proliferation of mononuclear histiocyte-like cells, multinucleated osteoclast-like cells, and spindle fibroblast-like cells in variable proportions and have three distinct growth patterns: fibrohistiocytic (36% of tumors), fibroblastic (32%), and mixed (32%), depending on the predominant cell type. Cellular atypia and pleomorphism are usually absent or minimal. Most tumors (78%) display mitotic activity, frequently <3 mitoses/10 high-power fields, and only 14% of the lesions display atypical mitoses. Vascular invasion was seen in only one tumor. Immunohistochemically, all tumors evaluated reacted with antibodies to CD68 that stained mainly the multinucleated giant cells and, to a lesser extent, mononuclear histiocyte-like cells and, occasionally, fibroblast-like cells. Less frequently, staining with antiactin antibodies was observed, restricted mainly to spindle cells. All nine tumors examined had a diploid DNA content. According to latest follow-up data (average period, 3.6 years) from 16 patients, 13 (82%) were alive with no evidence of disease (average, 3.6 years), 1 (6%) was alive with metastatic disease (follow-up, 2.3 years), 1 (6%) was alive with a stable pulmonary nodule of unknown nature (follow-up, 1.75 years), and 1 (6%) had died of disease 3 years after local recurrence and regional lymph node and pulmonary metastases developed. Two patients (12.5%) had local recurrence, 1 (6%) had regional lymph node metastasis, and 3 (19%) had pulmonary metastases. No proven association between clinicopathologic features and outcome was identified. In conclusion, plexiform fibrohistiocytic tumor is a rare mesenchymal neoplasm of young persons characterized by low-grade malignant behavior and is prone to recur locally and occasionally to metastasize regionally and systemically.