Pathology of hairy-cell leukaemia

CD5-Negative, CD10-Negative Low-Grade B-Cell Lymphoproliferative Disorders of the Spleen

CD5-negative, CD10-negative low-grade B-cell lymphoproliferative disorders (CD5-CD10-LPD) of the spleen comprise a fascinating group of indolent, neoplastic, mature B-cell proliferations that are essential to accurately identify but can be difficult to diagnose. They comprise the majority of B-cell LPDs primary to the spleen, commonly presenting with splenomegaly and co-involvement of peripheral blood and bone marrow, but with little to no involvement of lymph nodes. Splenic marginal zone lymphoma is one of the prototypical, best studied, and most frequently encountered CD5-CD10-LPD of the spleen and typically involves white pulp. In contrast, hairy cell leukemia, another well-studied CD5-CD10-LPD of the spleen, involves red pulp, as do the two less common entities comprising so-called splenic B-cell lymphoma/leukemia unclassifiable: splenic diffuse red pulp small B-cell lymphoma and hairy cell leukemia variant. Although not always encountered in the spleen, lymphoplasmacytic lymphoma, a B-cell lymphoproliferative disorder consisting of a dual population of both clonal B-cells and plasma cells and the frequent presence of the MYD88 L265P mutation, is another CD5-CD10-LPD that can be seen in the spleen. Distinction of these different entities is possible through careful evaluation of morphologic, immunophenotypic, cytogenetic, and molecular features, as well as peripheral blood and bone marrow specimens. A firm understanding of this group of low-grade B-cell lymphoproliferative disorders is necessary for accurate diagnosis leading to optimal patient management.

BRAF V600E mutation detection in hairy cell leukemia-utility of archival DNA from bone marrow aspirate/imprint smear and amplification refractory mutation system

BRAF V600E is a disease defining mutation for hairy cell leukemia (HCL), which helps in its diagnosis and differentiation from morphologically similar splenic marginal zone lymphoma (SMZL) and HCL-variant (HCL-v). Forty eight cases:HCL(n = 34), SMZL(n = 11) and HCL-v(n = 3) were included. Of these, 32 were retrospective and 16 were prospective. DNA was extracted, in retrospective cases from cells obtained by smears from bone marrow aspirate/trephine imprint (BMA/BMTx) slides, and in prospective cases from peripheral blood (PB)/BMA samples. BRAF V600E mutation testing was done using ARMS-PCR. BRAF V600E mutation was positive in all HCL and negative in all SMZL and HCL-v cases. DNA extracted from BMA/BMTx slides gave results comparable to DNA extracted from PB/BMA samples. Median age of presentation for HCL (53 years) and SMZL (56 years) were quite similar, however, HCL-v (71 years) cases presented at an older age. Statistically significant differences between the three groups were seen for total leucocyte, platelet, absolute lymphocyte and monocyte counts, bone marrow-infiltration pattern, reticulin fibrosis, and an expression of CD11c, CD25, CD103, CD123, and CD200. The use of BMA/BMTx smears for DNA extraction was found to be a useful alternative to DNA extraction from formalin-fixed paraffin-embedded biopsy sections. ARMS-PCR is an efficient and specific technique to detect BRAF V600E mutation in HCL patients.

Deciphering the genotype and phenotype of hairy cell leukemia: clues for diagnosis and treatment

Introduction: Hairy cell leukemia (HCL) is a rare, indolent B-cell neoplasm. The classical variant of the disease is characterized by the BRAF V600E mutation, which is present in virtually all cases. How this mutation leads to the signs and symptoms of the disease is currently not known. Areas covered: This review explores the genetic background of HCL, especially the BRAF V600E driver mutation, but passenger mutations and their effects are also included. The clinical significance of BRAF mutations in other cancer types is discussed, as well as BRAF- induced senescence. An overview of the major forms of treatment of HCL (cytostatic drugs, specific BRAF inhibitors, B cell-specific antibodies) is given. Finally, possible mechanisms of the monocytopenia and hairy morphology so typical of this disease are discussed. Expert opinion: Although being a rare disease, HCL and its pathogenesis can yield important information about BRAF-related cancer metabolism. Many aspects of the disease are still unclear, but with the right resources, this could change. This can lead to a more efficient and specific treatment, thus leading to decreased morbidity.

Recent advances in diagnosis and treatment of hairy cell leukemia

Hairy cell leukemia (HCL) is a rare, indolent B-cell lymphoproliferative disorder that accounts for 2% of all cases of leukemia. Most patients present with pancytopenia and splenomegaly with variable number of ‘hairy’ lymphocytes in blood. BRAF V600E mutation can be detected in virtually 100% of HCL cases and is absent in other B-cell lymphomas. The mutated gene and its responding abnormal protein can be used as specific markers in the diagnosis of HCL. New therapeutic modalities targeting on mutated BRAF and its downstream pathways have shown encouraging results in clinical trials. The objective of this review article is to discuss the recent developments in the diagnosis and management of hairy cell leukemia.

Hairy Cell Leukemia Presenting with Duodenal Involvement Duodenum: A Case Report

Context:

A rare case of adult hairy cell leukemia (HCL) with duodenal involvement is presented.

Case Report:

The patient was a 48-year-old man, who had a history of hairy cell leukemia. Three days after completion of 2-chlorodeoxyadenosine (CDA) chemotherapy, the patient started experiencing abdominal pain. An extensive gastroenterological workup culminated in the patient getting an esophagogastroduodenoscopy (EGD) that revealed duodenal inflammation and biopsies were taken. The duodenal biopsy was positive for chronic inflammatory infiltrate, primarily consisting of atypical lymphocytes and plasma cells with tartrate-resistant acid phosphatase (TRAP) positivity, and hence a diagnosis of duodenal involvement with HCL was made. Repeat bone marrow biopsy done 2 weeks after finishing chemotherapy revealed residual disease. At the 3-month follow-up, the patient was asymptomatic with a normocellular marrow and no residual disease. Repeat abdomen computerized tomography (CT) scan at completion of therapy showed resolution of duodenal thickening and spleen size of 12 cm. Currently, patient is in clinical remission for 6 years with 4-6 monthly follow-up visits and continues to do well.

Conclusion:

This case is presented to highlight the first case report of HCL with duodenal involvement that was successfully treated with CDA.

Primary hairy cell leukemia/lymphoma of the breast: a case report and review of the literature

Hairy cell leukemia/lymphoma (HCL) is a rare B-cell neoplasm primarily involving spleen, bone marrow, and blood. However, other sites of primary involvement do occur and can present a diagnostic and therapeutic challenge. We present an unusual case of HCL involving predominantly the breast that was diagnosed as an incidental finding during an elective reduction mammoplasty in an otherwise healthy asymptomatic woman. Bone marrow performed for staging revealed limited involvement by HCL. Notably, there was no splenomegaly and/or involvement of other extramedullary sites. The peripheral blood revealed minimal involvement detected by flow cytometry. Extensive immunohistochemical studies supported by positive BRAF V600E mutational status confirmed the diagnosis of HCL. The patient remains asymptomatic without treatment one year following the diagnosis. This is the first case of a well-documented HCL presenting primarily in the breast in an asymptomatic patient. We review the literature on extramedullary, extrasplenic involvement by HCL and discuss the diagnostic challenges as well as the utility of immunohistochemistry and molecular studies in the diagnosis of atypical presentations of HCL.

Hairy cell leukemia

Progress in the treatment of patients with hairy cell leukemia (HCL) has led to a significant change in the natural history of the disease. With current regimens, the majority of patients achieve a complete remission, and their survival curves are similar to those for appropriate age-matched individuals without the disease. At the same time, new technologies are allowing better understanding of the molecular mechanisms responsible for the pathogenesis of this and other indolent lymphoid neoplasms. Several studies using modern techniques with different sensitivities have demonstrated the persistence of minimal residual disease (MRD) after therapy with nucleoside analogues in majority of patients. However, it is not clear whether such MRD would invariably lead to leukemia recurrence or what level of MRD can predict relapse. The role of monoclonal antibodies, naked or conjugated with toxins, in the management of HCL and their ability to eradicate MRD is under investigation. Whether such strategies of chemoimmunotherapy would lead to further improvements in the outcome of patients with HCL needs to be further investigated.

Multiple opportunistic infections after high-dose steroid therapy for giant cell arteritis in a patient previously treated with a purine analog

We present the case of a 74-y-old HIV-negative female who suffered simultaneously from multiple opportunistic infections and a Klebsiella pneumoniae sepsis during high-dose steroids for giant cell arteritis. The patient was treated with a purine analog due to hairy cell leukaemia 10 y previously. Purine analog therapy can lead to long lasting defects in cell-mediated immunity. In these patients, treatment with steroids should be closely monitored with CD4 counts.

The leukemias of mature lymphocytes

The leukemias of mature B cells and T cells are a limited set of diseases in which blood and bone marrow are the primary sites of involvement. Although they may superficially resemble one another, they have distinct clinical and pathologic features and must be distinguished from one another. In this article, the major clinical, morphologic, phenotypic, and molecular genetic features of the mature B- and T-cell leukemias are reviewed, and differential diagnostic considerations are discussed.

Recombinant immunotoxins for the treatment of chemoresistant hematologic malignancies

Recombinant immunotoxins are proteins composed of fragments of monoclonal antibodies fused to truncated protein toxins. No agents of this class are approved yet for medical use, although a related molecule, denileukin diftitox, composed of interleukin-2 fused to truncated diphtheria toxin, is approved for relapsed/refractory cutaneous T-cell lymphoma. Recombinant immunotoxins which have been tested in patients with chemotherapy-pretreated hematologic malignancies include LMB-2 (anti-CD25), BL22 (CAT-3888, anti-CD22) and HA22 (CAT-8015, anti-CD22), each containing an Fv fragment fused to truncated Pseudomonas exotoxin. Major responses were observed with LMB-2 in adult T-cell leukemia, chronic lymphocytic leukemia (CLL), cutaneous T-cell lymphoma, Hodgkin's disease, and hairy cell leukemia (HCL). BL22 resulted in a high complete remission rate in patients with HCL, particularly those without excessive tumor burden. HA22, an improved version of BL22 with higher affinity to CD22, is now undergoing phase I testing in HCL, CLL, non-Hodgkin's lymphoma, and pediatric acute lymphoblastic leukemia.

Hairy cell leukaemia: a heterogeneous disease?

The US National Cancer Institute's Surveillance, Epidemiology and End Results program was used to develop aetiological clues for hairy cell leukaemia (HCL). Descriptive techniques (age-adjusted incidence trends, age-specific incidence rates (IR), and age distributions-at-diagnosis) were supplemented with mathematical models (two-component mixture, generalized linear regression, and age-period-cohort). There were 2856 cases of HCL diagnosed during 1978-2004 (IR 0.32/100,000 person-years). IRs were nearly 4-fold greater among men than women and more than 3-fold higher for Whites than Blacks. Temporal trends were stable over time. Age-specific IRs increased rapidly until approximately 40 years then rose at a slower pace. The age-specific IR curves reflected bimodal early- and late-onset age distributions-at-diagnosis (or density plots), with some variation by gender. Among both men and women, a two-component mixture model fitted the data better than a single density or cancer population. Age-period-cohort models confirmed statistically significant age-related effects after full adjustment for temporal trends (calendar-period and birth-cohort effects). In summary, age incidence patterns (rates and bimodal densities) suggested that HCL is a heterogeneous disease, consisting of at least two underlying subgroups and/or cancer populations by age-at-onset. Distinct early- and late-onset HCL populations may reflect different age-related causal pathways, risk factor profiles, and/or stem cells of origin.

Hairy cell leukemia presenting as a discrete liver mass: diagnosis by fine needle aspiration biopsy

Hairy cell leukemia, a chronic low-grade lymphoproliferative disorder first recognized in mid 1920's typically involves the lymphoreticular system, especially the spleen and the bone marrow. Clinically, it tends to present with pancytopenia and splenomegaly. Liver involvement, if present, is usually in a sinusoidal and a periportal pattern. We report a case of hairy cell leukemia associated with a liver mass 20 years after the initial presentation. To our knowledge, this is the first case of hairy cell leukemia presenting as a solid liver mass diagnosed by a percutaneous ultrasound guided fine needle aspiration biopsy to be reported in the English literature.

Splenic red pulp lymphoma with numerous basophilic villous lymphocytes: a distinct clinicopathologic and molecular entity?

The presence of circulating villous lymphocytes (VLs) in lymphoma patients usually points to splenic marginal zone B-cell lymphoma (SMZL), even if the VLs can be found occasionally in other small B-cell lymphomas. However, those cells are variably described, and detailed cytologic characterization is often lacking. We identified lymphoma cases with numerous basophilic VLs among the large group of splenic lymphoma with VLs, and for further delineation, 37 cases with this particular cytology were analyzed. Patients, predominantly older men, presented with moderate lymphocytosis and splenomegaly without pancytopenia. The monoclonal B cells expressed IgM + D, IgM + G, IgM or IgG, as well as CD76 and CD11c, frequently CD103, and rarely CD123. Spleen sections were peculiar, with atrophic white pulp and a monomorphic diffuse lymphoma infiltration in a congested red pulp. Bone marrow infiltration was interstitial and intrasinusoidal without extensive fibrosis. Cytogenetic analysis showed a frequent absence of clonal aberrations (68%). Most cases (79%) were IgH mutated, with an overrepresentation of VH3 and VH4 gene families. These results, as well as the clinical evolution, show that those lymphoma cases represent a homogeneous group distinct from SMZL and reminiscent of hairy cell leukemia variant, perhaps corresponding to a separate lymphoma entity.

T-bet Transcription Factor Detection Facilitates the Diagnosis of Minimal Hairy Cell Leukemia Infiltrates in Bone Marrow Trephines

Diagnosis of minimal infiltration by hairy cell leukemia (HCL) cells in bone marrow trephines is challenging as its differentiation from interstitially distributed infiltrates of reactive B cells and small B-cell lymphomas other than HCL is difficult or impossible. The diagnostic utility of DBA.44, tartrate-resistant acid phosphatase (TRAP) and of the recently propagated Annexin A1 is limited in this diagnostic setting since DBA.44 does not always label all HCL cells, TRAP is frequently weakly expressed whereas the numerous Annexin A1-positive hematopoietic cells interfere with the immunohistochemical recognition of sparse HCL cells. Therefore, we searched for antibodies suitable for the identification of minimal HCL infiltrates in formalin-fixed bone marrow trephines. Among the antibodies tested those directed against the T-cell associated transcription factor T-bet showed the required specificity: (1) T-bet is highly expressed in all 85 cases of HCL including 31 cases showing only minimal infiltrates, and (2) T-bet is exclusively expressed only on a subset of reactive T cells which are rare in bone marrow. Although T-bet is also weakly expressed in a proportion of the tumor cells of some small B-cell lymphomas (n=32/69) other than HCL, a reliable distinction is nevertheless easily possible because (1) T-bet is strongly expressed by all hairy cells of all HCL cases and (2) T-bet is not coexpressed in HCL with markers typical for other small B-cell lymphomas/leukemias (ie, CD23, CD5, CD10, and/or BCL6). Therefore, the immunohistochemical detection of T-bet in infiltrated bone marrow trephines represents an important adjunct for the diagnosis of HCL.

Minimal residual disease in hairy cell leukemia patients assessed by clone-specific polymerase chain reaction

Cladribine induces long-term complete remission in hairy cell leukemia (HCL) patients but does not clear minimal residual disease (MRD) according to high-sensitivity PCR assays. To quantify MRD in patients after anti-CD22 recombinant immunotoxin BL22 and other agents, we used a relative quantitative PCR (RQ-PCR) assay using a primer and probe, both patient specific for the immunoglobulin heavy chain rearrangement. Using this method, we were able to detect one Bonna 12 HCL cell in either 10(6) Jurkat cells or in 10(6) normal mononuclear cells. We studied 84 samples from 10 patients, taken before or after treatment with BL22 and other agents. Patient-specific RQ-PCR was much more sensitive than flow cytometry, which in turn was (as recently reported) more sensitive than PCR using consensus primers. RQ-PCR was positive in 62 of 62 (100%) flow-positive samples in 10 patients and in 20 of 22 (91%) flow-negative samples in six patients. The relative level of MRD as quantified by RQ-PCR correlated with disease status and remission. Thus, patient-specific RQ-PCR is the most sensitive test for MRD in HCL patients and could be used to determine maximal response in patients obtaining multiple cycles of nonmyelotoxic biological treatment for this disease.

Somatic hypermutation and VH gene usage in hairy cell leukaemia

To examine the usage and mutational status of VH genes in hairy cell leukaemia (HCL), we analysed 24 immunoglobulin heavy chain (IgH) sequences expressed in 23 patients. None had premature stop codons. VH3-23 was the most common gene and a VH6 gene was observed for the first time in HCL. Although the mean mutation frequency was 6.1%, slightly higher than in previous HCL series, four patients had 99.6-100% homology to germline sequences, three of whom had high tumour burdens and poor outcomes. Despite the high mutation frequency, only two of 24 rearrangements had clear statistical evidence of antigen-dependent somatic mutation. Our results increase the database of reported functional HCL rearrangements to 94 in 92 patients. Overall, both gene usage and mutation frequency are very similar to mucosa-associated lymphoid tissue-type marginal zone lymphoma. The data are consistent with HCL originating from post-germinal centre marginal zone B cells, although the heterogeneity observed suggests that HCL may originate differently in some patients, and this could have implications for prognosis and treatment.

Hairy cell leukemia: a diagnosis by endoscopic ultrasound guided fine needle aspiration

Background

Endosonography (EUS) guided FNA is a relatively new imaging modality which is increasingly used for sampling deep-seated lymph nodes in the diagnosis and staging of various malignancies, both primary as well as metastatic. It is also useful for staging of non-Hodgkin's lymphoma as well as diagnosing recurrence. The diagnosis of leukemia on FNA samples from deep-seated lymphadenopathy poses an even greater challenge. Hairy cell leukemia (HCL) is an uncommon, but distinct, lympho-proliferative disorder of B cell origin. It usually affects the spleen and bone marrow and uncommonly involves lymph nodes. There are only a few cases reported where HCL was diagnosed on FNA specimens.

Case presentation

We report the first case of HCL accurately rendered on EUS-FNA samples.

Conclusion

This report underscores the concept that the presence of a cytopathologist in the endoscopy suite plays an important role in providing accurate diagnoses of lymphoid lesions biopsied with EUS-FNA.

Chronic lymphoid leukemias other than chronic lymphocytic leukemia: diagnosis and treatment

The World Health Organization classification divides lymphoid malignancies into precursor B-cell and T-cell neoplasms as well as mature B-cell and T-cell neoplasms. Mature B-cell neoplasms comprise more than 85% of non-Hodgkin lymphomas worldwide and can be further subclassified according to the postulated cell of origin by using specific morphologic, immunophenotypic, and molecular characteristics. Similarly, the more uncommon mature T-cell neoplasms have been better characterized to include numerous distinct entities with widely varying natural histories. The distinction between lymphoma and leukemia is somewhat arbitrary and is based on variable involvement of the bone marrow, peripheral blood, and lymphatic system. In this article, we review the diagnostic and clinical features of mature B-cell and T-cell lymphoproliferative disorders that commonly have a leukemic presentation.