Pediatric mast cell sarcoma of temporal bone with novel L799F (2395 C>T) KIT mutation, mimicking histiocytic neoplasm.

Mast cell sarcoma (MCS) is an extremely rare neoplasm with a clinically aggressive course. Because of its rarity, its morphologic and molecular characteristics are still not well defined. We report a case of a 15-year-old girl with MCS of the temporal bone extending into the posterior fossa creating a mass effect. The lesion mimicked a histiocytic neoplasm morphologically, but showed a novel KIT missense mutation, L799F (2395 C>T). The KIT D816V mutation is frequently found in systemic mastocytosis, but it has not been documented in the few reported human MCS cases. However, 1 reported case of MCS has shown a different alteration in the KIT gene. Our case is the first MCS case with L799F mutation, located between the catalytic loop (790 to 797) and the activation loop (810 to 837) of the KIT gene, and only the second case of MCS with KIT mutation documented in the literature. Proximity of the L799F mutation to the enzymatic region of the KIT tyrosine kinase domain may induce resistance to tyrosine kinase inhibitors.

Primary anaplastic large-cell lymphoma associated with breast implants.

Primary T-cell anaplastic large-cell lymphoma (ALCL) of the breast is a rare entity, which has been reported in association with breast implants. In a retrospective analysis of the City of Hope pathology database, we uncovered nine such patients, eight of whom had breast implants proximal to primary ALCL. The diagnosis of ALCL in the implant capsule occurred at a median of 7 years (range 5-30) following implant surgery, and median patient age was 45.5 years (range 32-62). Malignancy was effusion-associated in two cases and tissue-associated in six. Seven patients were negative for anaplastic large-cell kinase (ALK) and one patient was positive. Treatment and follow-up data were available for four patients, all tissue-associated cases: two patients were lost to follow-up after failing to mobilize stem cells and two patients were in remission, 6 years and 7.5 years post-autologous transplant. These cases represent 24% of reported primary ALCL cases associated with breast implants. Our review of these cases and the literature suggest that (1) there is a strong skew in primary breast lymphomas associated with implant capsules toward T-cell, ALCL ALK-, and (2) the disease course for tissue-associated cases is not always indolent, with four patients requiring multiple treatment regimens.

Practical immunohistochemistry in hematopathology: a review of useful antibodies for diagnosis.

This review article offers some useful panels of immunohistochemical stains and discusses their use in determining a hematopathology diagnosis. As a comprehensive review of the vast array of hematolymphoid malignancies is beyond the scope of this study, the suggestions are based on broad morphologic categories such as follicular proliferations, paracortical expansions, diffuse small-cell infiltrates, diffuse large-cell infiltrates, and Hodgkin-like infiltrates. The review article also discusses the most common hematolymphoid malignancies and their immunohistochemical profiles, and how to use immunophenotyping to differentiate them from other entities. Common diagnostic pitfalls and misconceptions about certain antibodies will also be discussed. New antibodies, such as SOX11, will also be explored in the context of specific disease entities for which they may be of use.

Accelerated telomere shortening precedes development of therapy-related myelodysplasia or acute myelogenous leukemia after autologous transplantation for lymphoma.

PURPOSE: Therapy-related myelodysplasia or acute myelogenous leukemia (t-MDS/AML) is a lethal complication of autologous hematopoietic stem-cell transplantation (aHCT) for Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). Here, we investigated the hypothesis that accelerated telomere shortening after aHCT could contribute to the development of t-MDS/AML. PATIENTS AND METHODS: A prospective longitudinal cohort was constructed to investigate the sequence of cellular and molecular abnormalities leading to development of t-MDS/AML after aHCT for HL/NHL. This cohort formed the sampling frame for a nested case-control study to compare changes in telomere length in serial blood samples from patients who developed t-MDS/AML with matched controls who did not develop t-MDS/AML. RESULTS: An initial increase in telomere length at day 100 after aHCT was followed by an accelerated telomere shortening in t-MDS/AML patients when compared with controls. These telomere alterations preceded the onset of t-MDS and were independent of other known risk factors associated with development of t-MDS/AML on multivariate analysis. Additionally, we observed reduced generation of committed progenitors in patients who developed t-MDS/AML, indicating that these telomere alterations were associated with reduced regenerative capacity of hematopoietic stem cells. CONCLUSION: The development of t-MDS/AML after aHCT is associated with and preceded by markedly altered telomere dynamics in hematopoietic cells. Accelerated telomere loss in patients developing t-MDS/AML may reflect increased clonal proliferation and/or altered telomere regulation in premalignant cells. Genetic instability associated with shortened telomeres may contribute to leukemic transformation in t-MDS/AML.

Aberrant expression of CD7 in myeloblasts is highly associated with de novo acute myeloid leukemias with FLT3/ITD mutation.

Acute myeloid leukemia (AML) with normal cytogenetics represents approximately 40% to 50% of de novo AML. This heterogeneous AML subgroup constitutes the single largest cytogenetic group with an intermediate prognosis. Previous studies have suggested that the Fms-like tyrosine kinase-3 internal tandem duplication (FLT3/ITD) mutation-positive de novo AML may represent a distinctive subgroup of AML. We analyzed the clinical and pathologic features of 15 cases of de novo AML with normal cytogenetics and with the FLT3/ITD mutation. In comparison with patients with AML without the FLT3/ITD mutation, patients with FLT3/ITD+ AML are relatively younger, more often have marked peripheral leukocytosis with a higher number of circulating blasts at initial examination, more often have minimal differentiation morphologic features, more frequently have abnormal CD7 coexpression, and have poorer outcome. Close association of aberrant CD7 expression and FLT3/ITD mutation in the myeloblasts of FLT3/ITD+ AML suggests that FLT3/ITD- mediated leukemic transformation occurs in the more early stage of myeloid progenitor cells.

High prevalence of epstein-barr virus in the reed-sternberg cells of Hodgkin's disease occuring in Peru

The Epstein-Barr virus (EBV) has been implicated in the pathogenesis of Hodgkin's disease (HD). This study was undertaken to determine whether the association of EBV with HD showed geographical variation, as in Burkitt's lymphoma. We studied 32 formalin-fixed, paraffin-embedded cases of HD occuring in Peru. EBV DNA-RNA in situ hybridization was performed using a 30-base biotinylated antisense oligonucleotide complementary to the EBER1 gene of EBV. EBV immunohistochemistry was also performed, using a monoclonal antibody (MoAb) to the latent membrane protein (LMP1) of EBV. Identification of the precise cellular subset staining with EBV was accomplished via double-labeling with MoAbs directed against Reed-Stemberg cells (LeuM1/CD15) and B cells (L26/CD20). EBVRNA was identified in all or virtually all of the Reed-Sternberg cells and variants in 30 of the 32 (94%) cases of HD by in situ hybridization. LMP1 expression was identified in 83% of the EBER1-positive cases. Double-labeling studies confirmed the localization of EBV RNA to CD15-expressing Hodgkin's cells. This study found an extremely high prevalence of EBV in Peruvian HD, in contrast to the much lower percentage of EBV-associated cases of HD occurring in"Western" patients.

Clinical and pathologic analysis of 16 cases of relapsed chronic myeloid leukemia after stem cell transplantation.

Chronic myeloid leukemia (CML) is a myeloproliferative disease that originates in an abnormal pluripotent bone marrow stem cell and is characteristically associated with the Philadelphia chromosome and/or the bcr/abl fusion gene. Despite the exciting success of the bcr/abl tyrosine kinase-specific inhibitor imatinib for CML treatment, hematopoietic stem cell (bone marrow or peripheral blood stem cell) transplantation (HCT) remains the only "curative" approach for the majority of patients. Although HCT outcomes for patients with CML have improved considerably during the past 2 decades, relapse after HCT may occur. We analyzed the clinical and pathologic features of 16 cases of hematologically relapsed CML after HCT during a 5-year period at City of Hope National Medical Center, Duarte, CA. The results of our analysis showed that relapsed CML after HCT frequently manifested with advanced disease with a more aggressive clinical course and was often refractory to therapy. The frequency of acute leukemic transformation at time of relapse was largely associated with pre-HCT disease status and acquired secondary cytogenetic abnormalities. Disease mortality in patients with relapsed CML after HCT was closely associated with advanced disease and HCT-related complications.

Composite recurrent hodgkin lymphoma and diffuse large B-cell lymphoma: one clone, two faces.

We describe a composite lymphoma with recurrent Hodgkin lymphoma and diffuse large B-cell lymphoma components manifesting as a single, perforated small intestinal tumor in a 56-year-old man with a history of classical Hodgkin lymphoma and recent relapse in the bone marrow. The resected mass had 2 morphologically and immunophenotypically distinct components; 1 showed a pleomorphic cellular infiltrate with fibrosis and contained numerous, large Hodgkin/Reed-Sternberg-like cells and variants. The tumor cells were CD30+ and focally positive for CD15 but CD20-, CD79a-, and PAX-5-. In situ hybridization for Epstein-Barr virus (EBV) was strongly positive in the large pleomorphic tumor cells. The adjacent component displayed sheets of relatively uniform, large lymphoid cells with typical morphologic features of diffuse large cell lymphoma. The tumor cells showed uniform expression of tested B-cell antigens, absence of CD30 or CD15, and complete absence of EBV-encoded RNA. Separate molecular studies with immunoglobulin heavy and k light chain gene rearrangements clearly demonstrated an identical rearrangement pattern, indicating derivation from the same clone, which was confirmed by direct DNA sequencing analysis. Such distinctly different morphology, immunophenotype, and EBV status in different components within a clonally related single tumor mass is striking.

Low CD27 expression in plasma cell dyscrasias correlates with high-risk disease: an immunohistochemical analysis.

Genome-wide expression studies using complementary DNA microarrays recently suggested a number of intriguing candidate genes for distinguishing plasma cell dyscrasias. Our objective was to test select markers using immunohistochemical analysis and a tissue microarray from paraffin-embedded bone marrow core biopsy specimens obtained from 8 patients with monoclonal gammopathy of undetermined significance, 17 with plasmacytoma, 160 with multiple myeloma, and 15 with plasma cell leukemia (PCL). We immunostained serial sections for CD138, CD27, CD56, p27, Ki-67, CD3, and CD20. Each core was scored in duplicate by observers blinded to phenotype and reported as the average percentage of CD138+ cells. The Mann-Whitney U test was used to determine significance between groups. PCL showed significantly less immunostaining for CD27 (P < .01) and p27 (P < .05) compared with plasmacytoma and multiple myeloma. Low CD27 expression also was associated with plasmacytoma progression to multiple myeloma (P <.05). Our results support the hypothesis that low CD27 expression correlates with high-risk disease, including primary PCL and decreased progression-free survival in solitary plasmacytoma.

Extranodal Rosai-Dorfman disease involving the bone marrow: a case report.

Sinus histiocytosis with massive lymphadenopathy (SHML), also known as Rosai-Dorfman disease, is a very rare disorder of unknown etiology. Although classical SHML usually presents as massive, painless, bilateral neck lymph node enlargement, approximately 25% to 40% of SHML cases described to date present in extranodal organs or tissues, such as skin, upper respiratory tract, and bone etc. However, bone marrow as a site of initial presentation by SHML has not been described since the disease was initially recognized in 1969. Here, we report the first case of bone marrow involvement by extranodal SHML, which occured in a 73 year-old man with a history of refractory idiopathic thrombocytopenia purpura. The bone marrow biopsy demonstrates the distinctive and characteristic morphologic and immunophenotypic features of extranodal SHML.

An aggressive extranodal NK-cell lymphoma arising from indolent NK-cell lymphoproliferative disorder.

Indolent NK-cell lymphoproliferative disorder, also known as chronic natural killer (NK) cell large granular lymphocytosis (leukemia), is a very rare entity in the World Health Organization (WHO) Classification of Tumors of Hematopoietic & Lymphoid Tissues. Unlike aggressive NK-cell leukemia, which is malignant, the WHO does not specify whether indolent NK-cell lymphoproliferative disorder is reactive or neoplastic. Patients with indolent NK-cell lymphoproliferative disorder are usually asymptomatic older adults who have a nonprogressive, very stable clinical course. We report an unusual case of an aggressive extranodal NK-cell lymphoma, non-nasal type, which presented as a subcutaneous tissue mass, which apparently transformed from a preexisting, untreated indolent NK-cell lymphoproliferative disorder in an 65-year-old otherwise healthy white man. The extranodal NK-cell lymphoma and the NK-cell lymphoproliferative disorder in the blood and bone marrow share a distinctive and identical NK-cell immunophenotype and genotype: CD56/CD8/TIA-1-positive and surface CD3-negative, negative for Epstein-Barr virus infection, and no evidence of T-cell and B-cell receptor gene rearrangements. To the best of our knowledge, such aggressive lymphomatous transformation in an indolent NK-cell lymphoproliferative disorder has not been previously reported.

Longitudinal assessment of hematopoietic abnormalities after autologous hematopoietic cell transplantation for lymphoma.

PURPOSE: Autologous hematopoietic cell transplantation (HCT) is being increasingly used as an effective treatment strategy for patients with relapsed or refractory Hodgkin's lymphoma (HL) or non-Hodgkin's lymphoma (NHL) but is associated with therapy-related myelodysplasia and acute myeloid leukemia (t-MDS/AML) as a major cause of nonrelapse mortality. The phenomenon of hematopoietic reconstitution after autologous HCT and the role of proliferative stress in the pathogenesis of t-MDS/AML are poorly understood. PATIENTS AND METHODS: Using a prospective longitudinal study design, we evaluated the nature and timing of alterations in hematopoietic progenitors and telomere length after HCT in patients undergoing autologous HCT at City of Hope Cancer Center (Duarte, CA). RESULTS: A significant reduction in primitive and committed progenitors was observed before HCT compared with healthy controls. Further profound and persistent reduction in primitive progenitors but only transient reduction in committed progenitors were seen after HCT. Primitive progenitor frequency in pre-HCT marrow and peripheral-blood stem cells predicted for primitive progenitor recovery after HCT. Shortening of telomere length was observed in marrow cells early after HCT, with subsequent restoration to pre-HCT levels. Patients within this cohort who developed t-MDS/AML had reduced recovery of committed progenitors and poorer telomere recovery, possibly indicating a functional defect in primitive hematopoietic cells. CONCLUSION: Our studies suggest that hematopoietic regeneration after HCT is associated with increased proliferation and differentiation of primitive progenitors. Increased proliferative stress on stem cells bearing genotoxic damage could contribute to the pathogenesis of t-MDS/AML. Extended follow-up of a larger number of patients is required to confirm whether alterations in progenitor and telomere recovery predict for increased risk of t-MDS/AML.

Targeting plasma cells improves detection of cytogenetic aberrations in multiple myeloma: phenotype/genotype fluorescence in situ hybridization.

Standard fluorescence in situ hybridization (FISH) easily detects nonrandom karyotypic abnormalities in multiple myeloma (MM) at disease presentation, when tumor burden is high. In contrast, the detection of residual MM using the standard 200 unselected nonmitotic nuclei FISH approach correlates poorly with residual disease detected by morphology, flow cytometry, immunohistochemistry, or reverse-transcription polymerase chain reaction (RT-PCR). We have used sequential May-Grunwald Giemsa stain to identify plasma cell populations, followed by FISH analyses (target FISH or T-FISH) to detect immunoglobulin heavy-chain gene (IGH) rearrangements, 13q or 17p deletions, or hyperdiploidy. In this study, 115 samples were collected from 100 patients with MM regardless of treatment status. In this proof-of-principle prospective study, T-FISH detected MM in 52 samples (45%), a percentage similar to that obtained by pathology. Disease detection increased from 5.6% with standard FISH to 48% with T-FISH, and cell culture experiments showed that T-FISH consistently detected a clonal abnormality at dilutions of 10(-3). In five patients, T-FISH further identified myelodysplastic-associated karyotypic changes restricted to myeloid cells. Our observations suggest that T-FISH identifies cell lineage involvement of cytogenetic abnormalities, improves detection of low-level or residual MM, and may define the coexistence of hematologic karyotypic changes in individual patients.

KSHV/HHV8-associated lymphoma simulating anaplastic large cell lymphoma.

We report a unique, previously undescribed case of KSHV/HHV8-associated lymphoma in a 49-year-old HIV-seropositive patient. The cervical lymph node-based lymphoma displayed distinctive characteristic features of preferential sinusoidal infiltrate and anaplastic cellular morphology, closely resembling classic anaplastic large cell lymphoma of the WHO classification both histologically and immunophenotypically. Paraffin immunohistochemical study showed that the lymphoma cells were strongly positive for KSHV/HHV8 latency-associated nuclear antigen, and PCR analysis confirmed the presence of KSHV/HHV8 infection. Epstein-Barr virus in situ hybridization was negative. Molecular study clearly demonstrated B-cell lineage with immunoglobulin heavy and kappa light chain gene rearrangements. This case may add to the spectrum of the heterogeneous category of KSHV/HHV8-associated B-cell lymphomas.

Histiocytic lesions involving the bone marrow.

Histiocytic lesions involving the bone marrow include a number of reactive and neoplastic disorders. This article discusses the morphologic, immunophenotypic, and genotypic features of a variety of diseases associated with histiocytes and/or monocytes. Lysosomal storage disorders and hemophagocytic syndromes are often first diagnosed by bone marrow examination. Granulomas involving the bone marrow may also be the first indication of a systemic disorder. Apart from acute and chronic monocytic leukemias, the bone marrow is rarely involved by malignant histiocytic disorders, of which Langerhans cell histiocytosis is the most common.

Detection of NPM/MLF1 fusion in t(3;5)-positive acute myeloid leukemia and myelodysplasia.

Balanced translocations are rare in myelodysplasia (MDS) and acute myeloid leukemia (AML) with multilineage dysplasia; however, the t(3;5)(q25;q35) and insertion variant occur in a subset of patients. To evaluate the possible genes involved in this translocation, we studied 6 cases with a t(3;5) by fluorescence in situ hybridization with probes directed against the nucleophosmin (NPM), EVI1, and Ribophorin genes, as well as a newly developed myeloid leukemia factor 1 (MLF1) BAC clone. The histologic spectrum of the cases was variable, ranging from refractory cytopenia with multilineage dysplasia to AML with multilineage dysplasia in the World Health Organization classification. An NPM/MLF1 fusion was identified in 5 of 6 cases, whereas the EVI1 and Ribophorin genes were not involved in any of the cases. The NPM/MLF1-positive cases were predominantly young adult males (median age, 33 years) who responded well to hematopoietic stem cell transplantation. These findings suggest that an NPM/MLF1 fusion is the primary molecular abnormality in t(3;5) MDS and AML with multilineage dysplasia, and also that cases with NPM/MLF1 may be clinically distinct from other MDS-associated disease.

Primary effusion lymphoma with subsequent development of a small bowel mass in an HIV-seropositive patient: a case report and literature review.

Primary effusion lymphoma is a distinct clinicopathologic entity usually characterized by presentation as a lymphomatous body cavity effusion in the absence of a solid tumor mass or dissemination during its clinical course. This lymphoma is typically present in human immunodeficiency virus (HIV)-infected patients and frequently associated with Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV8) viral sequences. Here we report a rare case of KSHV/HHV8-associated primary effusion lymphoma with secondary involvement of the small bowel as an obstructive tumor mass in an HIV-infected man. The solid small bowel lymphoma demonstrated essentially identical morphology, immunophenotype, KSHV/HHV8 viral status, and immunoglobulin light chain rearrangements to the pleural cavity-based primary effusion lymphoma in the same patient.