The variant form of hairy-cell leukaemia

Untangling hairy cell leukaemia (HCL) variant and other HCL-like disorders: Diagnosis and treatment

The variant form of hairy cell leukaemia (HCL-V) is a rare disease very different from hairy cell leukaemia (HCL), which is a very well-defined entity. The 5th WHO edition (Leukemia, 36, 2022 and 1720) classification (WHO-HAEM5) introduced splenic lymphomas/leukaemias including four different entities: (1) HCL, (2) splenic marginal zone lymphoma (SMZL) with circulating villous cells in the peripheral blood, (3) splenic lymphoma with prominent nucleolus (SLPN), which replaced HCL-V and CD5 negative B-prolymphocytic leukaemia (B-PLL), and (4) splenic diffuse red pulp lymphoma (SDRPL). All these entities have to be distinguished because of a different clinical course and the need for a different treatment. The diagnosis can be challenging because of complex cases and overlap and/or grey zones between all the entities and needs integrating clinical, histologic, immunophenotypic, cytogenetic and molecular data. We review the diagnostic criteria including clinical, immunophenotypic and molecular characteristics of patients with HCL-V and other HCL-like disorders including HCL, SDRPL, SMZL, B-PLL and the Japanese form of HCL. We also discuss the different criteria allowing us to separate these different entities and we will update the recent therapeutic options that have emerged, in particular the advances with chemoimmunotherapy and/or targeted therapies.

Splenic B-cell lymphoma/leukemia with prominent nucleoli: A three-case series of the newly named old entity and review of literature

CONTEXT

Splenic B-cell lymphoma/leukemia with prominent nucleoli (SBLPN) aka hairy cell leukemia variant (HCL-v) is a rare B-cell chronic lymphoproliferative disorder. The main diagnostic challenge is to differentiate SBLPN from Classical hairy cell leukemia (HCL-c), as the former faces inferior responses to therapies and a poor prognosis.

AIMS

The aim is to discuss the clinic-hematological and immunophenotyping findings of three cases of SBLPN.

SETTINGS AND DESIGN

This is a retrospective observational study.

METHODS AND MATERIAL

From the year 2011 to 2021, flow cytometry of all the cases with HCL diagnosis was reviewed, and three cases with negative or dim CD25 and hematological presentation matching with SBLPN were picked up.

STATISTICAL ANALYSIS USED

Descriptive statistics is used.

RESULTS

All the cases were male. The age ranges from 43 to 64 years. Median hemoglobin concentration, total leucocyte count, and platelet count were 8.6 g/dL, 6.9 × 109/L, and 53 × 109/L, respectively. The atypical cells were medium to large. All three showed prominent nucleoli. Bone marrow biopsies showed an interstitial pattern of infiltration in all the cases. The hairy cells were positive for CD20, CD11c, and CD103. CD25 was dim positive in one case. Annexin A1 was negative in all three cases. BRAF V600E mutation analysis was done in one case and turned out negative for the mutation.

CONCLUSIONS

SBLPN is a rare entity, usually on-flow cytometry CD25 negative. However, in dim CD25-positive cases, BRAFV600E mutational analysis helps in discerning SBLPN diagnosis and differentiating it from HCL-c.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

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.

[Hairy cell leukemia: What are the best treatment options for relapsed or refractory patients?]

Hairy cell leukemia is a rare form of leukemia: three hundred new cases are diagnosed each year in France. The diagnosis is based on: (1) morphological examination of the blood and bone marrow smear, (2) analysis by flow cytometry of hairy cells, which express three or the four following markers: CD11c, CD25, CD103 and CD123, (3) identification of the BRAF^V600E mutation, a true molecular marker of the disease. The management of treatment has evolved considerably in recent years. As of today, the purine analogues remain the standard treatment in the first line. Relapses are however observed in about 40% of cases. In the event of a first relapse, the preferred option is treatment with immunochemotherapy i.e. a combination of cladribine plus rituximab. Subsequent relapses are treated with moxetumomab pasudotox or BRAF inhibitors which provide indisputable benefits if third-line treatment is required. We will discuss in patients with relapsed/refractory hairy cell leukemia the needs for personalized medicine and the advantages and disadvantages of each treatment modality. The good prognosis for LT requires treatments that are not immunosuppressive, non-myelotoxic, and do not increase the risk of secondary cancers.

Diagnostic and therapeutic challenges in hairy cell leukemia-variant: where are we in 2021?

INTRODUCTION

Hairy cell leukemia-variant (HCL-V) is a rare B-cell neoplasm arising or homing primarily in the spleen. It has been considered in the WHO classification of Hemopoietic and Lymphoid Tumors as a provisional entity since 2008 and included under the umbrella of unclassifiable splenomegalic B-cell leukemia/lymphomas. The diagnosis is a challenge to hematopathologists and management of these patients by the clinicians is difficult due to the lack of diagnostic and therapeutic guidelines and prospective studies.

AREAS COVERED

This manuscript is a comprehensive review of the clinical features, pathology, immunophenotypic profile, genomic alterations and therapeutic options of HCL-V. Diagnostic and therapeutic dilemmas are extensively outlined considering the information derived from a literature search covering from 1980 to 2019. Integration of all the data is needed and recommended for establishing the diagnosis of this leukemia.

EXPERT OPINION

More extensive information of genomic aberrations underlying the pathogenesis of the disease would be a solid stone for the diagnosis. To this end, a collaborative work among scientists and pathologists from different centers is required and expected. In turn, this might have a relevant clinical translation by allowing to identify putative targets for therapy and to improve the outlook of these patients.

A rare case of hairy cell leukemia with co-expression of CD5 and cyclin D1: A diagnostic pitfall

Hairy cell leukemia (HCL) is an uncommon chronic B-cell lymphoproliferative disease with an indolent course. It mainly occurs in elderly men, although abdominal lymphadenopathy is rare. HCL cells are mostly found in the bone marrow, peripheral blood, and spleen and typically express CD11c, CD20, CD25 and CD103. We present a case of HCL with a novel immunophenotype. A 48-year-old woman presented with pancytopenia and splenomegaly. The diagnosis was HCL with lymph node infiltration. Unlike previously described HCL cases, the current case showed strong expression of CD5 and cyclin D1 in the lymph nodes. The patient underwent cladribine chemotherapy, and the leukocyte count increased during and after treatment. The 8-month follow-up revealed that she had recovered well. This case highlights the distinctive immunophenotype of HCL infiltrating the lymph nodes and the potential misdiagnosis of HCL as mantle cell lymphoma. It also adds to our limited understanding of HCL.

B-cell neoplasms and Hodgkin lymphoma in the spleen

B-cell lymphoma of spleen may be primary (most commonly splenic diffuse large B-cell lymphoma) or secondary (typically low-grade non-Hodgkin lymphoma). Depending on the specific lymphoma subtype, there may be a predominantly white pulp pattern of involvement, a predominantly red pulp pattern or a focal nodular pattern. Splenectomy is the ideal specimen for a multiparametric integrative diagnosis of splenic lymphoma, as it allows for a combined study of morphology, immunohistology, flow cytometry, cytogenetics, and molecular genetic techniques. This review article describes the clinicopathologic characteristics of all the relevant B-cell neoplasms that may be encountered in a splenic biopsy or a splenectomy specimen.

Hairy Cell Leukaemia

PURPOSE OF REVIEW

To summarise diagnostic clinical/laboratory findings and highlight differences between classical hairy cell leukaemia (HCLc) and hairy cell leukaemia variant (HCLv). Discussion of prognosis and current treatment indications including novel therapies, linked to understanding of the underlying molecular pathogenesis.

RECENT FINDINGS

Improved understanding of the underlying pathogenesis of HCLc, particularly the causative mutation BRAF V600E, leading to constitutive activation of the MEK/ERK signalling pathway and increased cell proliferation. HCLc is caused by BRAF V600E mutation in most cases. Purine nucleoside analogue (PNA) therapy is the mainstay of treatment, with the addition of rituximab, improving response and minimal residual disease (MRD) clearance. Despite excellent responses to PNAs, many patients will eventually relapse, requiring further therapy. Rarely, patients are refractory to PNA therapy. In relapsed/refractory patients, novel targeted therapies include BRAF inhibitors (BRAFi), anti-CD22 immunoconjugate moxetumomab and Bruton tyrosine kinase inhibitors (BTKi). HCLv has a worse prognosis with median overall survival (OS), only 7-9 years, despite the combination of PNA/rituximab improving front-line response. Moxetumomab or ibrutinib may be a viable treatment but lacks substantial evidence.

Contextualizing the Use of Moxetumomab Pasudotox in the Treatment of Relapsed or Refractory Hairy Cell Leukemia

Hairy cell leukemia (HCL) is an indolent B-cell malignancy characterized by high initial sensitivity to purine analog chemotherapy, minimal residual disease (MRD) frequently accompanying complete remission (CR), and relapses requiring additional treatment. Repeat chemotherapy shows decreasing efficacy and increasing toxicity with each course. Newer therapies targeting BRAF/MEK or Bruton's tyrosine kinase are effective but generally leave MRD. Rituximab has modest activity as a single agent and can achieve MRD-negative CR in combination with purine analogs, but there is significant toxicity from the chemotherapy. Moxetumomab pasudotox-tdfk (Moxe) is a biologic containing an antibody fragment (Fv) binding to CD22, attached to a portion of Pseudomonas exotoxin A. Binding to CD22 enables the toxin to enter and kill cells. Moxe is administered by 30-minute infusions on days 1, 3, and 5 of up to six cycles spaced 4 weeks apart. In phase I testing, 64% of 33 patients at the highest dose level achieved CR, most without MRD. Lack of MRD correlated with prolonged CR duration; of 11 MRD-negative CRs, 10 were still in CR after a median of 42 months of observation. In pivotal testing, 75% of 80 patients had a hematologic response, 41% with CR; 82% (27/33) of CRs were MRD-negative, and only 4 of the 27 MRD-negative patients relapsed during the follow-up period. Hemolytic uremic syndrome and capillary leak syndrome were each observed in 9% of patients, all reversible. In September 2018, the U.S. Food and Drug Administration approved Moxe for the treatment of relapsed/refractory HCL after ≥2 prior therapies. Moxe is undergoing further development in combination with rituximab. IMPLICATIONS FOR PRACTICE: Hairy cell leukemia (HCL) has effective treatments including purine analogs with and without rituximab, and oral inhibitors of BRAF, MEK and Bruton's tyrosine kinase (BTK). Despite these therapies, relapse occurs, and moxetumomab pasudotox has an important role in relapsed and refractory HCL because of its ability to achieve high rates of complete remissions (CRs) without chemotherapy; most of these CRs are without minimal residual disease (MRD). CR duration is enhanced in patients who achieve eradication of MRD. To improve the efficacy of this recombinant immunotoxin, a phase I trial is underway in combination with rituximab to reduce tumor burden and decrease immunogenicity.

Difference of genomic copy numbers alterations between hairy cell leukemia-variant and classical hairy cell leukemia: a pilot retrospective study in Chinese

Background: Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disorder. It has two pathological subtypes: classical HCL (HCL-C) and HCL-variant (HCL-V). HCL-C and HCL-V are distinct in morphology and immunophenotype. Their differentiation is important for patient management and clinical outcome, with HCL-V responding poorly to conventional HCL treatments. Recently, whole genomic sequencing has been used to identify the difference between HCL-C and HCL-V and mutation of BRAF^V600E has been proved to be a molecular hallmark of HCL-C. However, BRAF inhibitors were not effective in all HCL-C cases and HCL-V seems be lack of the high-frequency mutations. Therefore, it is necessary to compare the genomic changes between HCL-C and HCL-V by high-resolution studies, especially in Chinese population, the genomic alterations of HCL have rarely be reported. Methods: In this study, the clinical features of a total of 18 Chinese HCL patients were described. Single nucleotide polymorphism (SNP) array analysis was performed to evaluate the genomic copy number alterations (CNA) and copy neutral loss of heterozygosity (CN-LOH) on six HCL-Vs with CD25^-/BRAF^V600E- and four HCL-Cs with CD25⁺/BRAF^V600E+. Results: A total of 24 CNAs including seven chromosomal gains and 17 chromosomal losses, and 22 CN-LOHs were revealed. Five of the six cases of HCL-V showed 15 CNAs including four cryptic chromosomal gains and 11 chromosomal losses. Overlapping regions involving micro-deletion of chromosome 2q13 and large chromosomal loss of 14q were showed in HCL-V. In HCL-C, a total of nine CNAs were revealed in three of the four cases including three chromosomal gains and six chromosomal losses. No overlapping area was observed among the CNVs. 15 CN-LOHs were showed in five of the six cases of HCL-V and seven CN-LOHs was demonstrated in all of the four HCL-Cs. Conclusions: Comparing to Westerners, a relatively higher proportion of HCL-V in all HCL is observed in this study. CNAs and CN-LOHs were common in both HCL-V and HCL-C but the CNAs were different in them. HCL-C was characterized with the higher ratio of large chromosomal changes but lacked of recurrent CNAs, while HCL-V was presented with the higher incidence of cryptic CNAs and recurrent CNAs involving tumor-associated genes. It is necessary to further investigate the association of the genes, such as NPHP1 and TRAF3 genes, and HCL-V in the future study.

Differential Expression of CD43, CD81, and CD200 in Classic Versus Variant Hairy Cell Leukemia

BACKGROUND

Hairy cell leukemia (HCL) and hairy cell leukemia variant (HCLv) are rare diseases with overlapping clinicopathological features. Features distinguishing HCL from HCLv include expression of CD25, CD123, CD200, annexin-A1, and the presence of BRAF V600E mutation. HCLv typically lacks these markers, but they may occur in a subgroup of HCL patients with an aggressive clinical course. We examined CD43, CD81, CD79b, and CD200 expression in HCL and HCLv.

METHODS

Multiparametric flow cytometry (FCM) was performed on blood from 59 HCL and 15 HCLv patients for protocol entry. Mean fluorescent intensity (MFI) of CD43, CD79b, CD81, and CD200 was determined (for CD200, n = 17 and 7, respectively).

RESULTS

Median MFI of HCL vs HCLv was 545 vs 272 for CD43, 602 vs 2,450 for CD81, 4,962 vs 1,969 for CD79b, and 11,652 vs 1,405 for CD200, respectively. Analysis of the median differences, HCL minus HCLv (and their 95% confidence intervals and P-values) indicated that CD43 MFI (estimated median difference (95% CI): 212 [72-413; P = 0.0027) and CD200 MFI (9,883 [3,514-13,434]; P < 0.0001) were higher in HCL than in HCLv, while CD81 MFI (-1,858 [-2,604 to -1,365]; P < 0.0001) was lower in HCL than in HCLv. CD79b MFI HCL median was more than double that of HCLv, but the observed difference (1,571 [-739 to 4,417]) was consistent with the null hypothesis of no difference (P = 0.13).

CONCLUSIONS

CD200, CD43, and CD81 are likely differentially expressed between HCL and HCLv, reflecting their differing disease biology. Inclusion of these markers in FCM is potentially informative. © 2019 International Clinical Cytometry Society.

A rare case of B-lymphoproliferative disorder with villous lymphocytes harboring t(8;14)(q24;q32) translocation

Splenic lymphoma with villous lymphocytes (SLVL) or splenic marginal zone lymphoma with circulating villous lymphocytes is rare, and prolymphocytic transformation of SLVL is rarer. At present, only one case of SLVL with t(8;14)(q24;q32) translocation has been reported. In this study, we report a case of B-lymphoproliferative disorder with villous lymphocytes harboring t(8;14)(q24;q32) chromosome translocation that we inclined to SLVL with a prolymphocytic transformation. A 73-year-old female showed marked hepatosplenomegaly and high lymphocytosis (lymphocytes > 200 × 10⁹/L). The abnormal lymphocytes had short coarse villi and round nuclei with prominent nucleoli. The immunophenotypes showed CD19⁺, CD20⁺, HLA-DR⁺, CD22⁺, CD5⁺, Kappa⁺, CD25^dim, CD71^dim, Lambda^-, CD7^-, CD10^-, CD23^-, CD34^-, CD33^-, CD13^-, CD14^-, CD117^-, CD64^-, CD103^-, and CD11c^-. The karyotype showed complex abnormality: 46XX,+ 3,-10, t(8;14)(q24; q32)[11]/46XX[9]. The cytoplasmic projection, immunological characteristics, and trisomy 3 chromosome abnormality supported the diagnosis of SLVL. However, the presence of prominent nucleoli and high lymphocytosis suggested prolymphocytic transformation, probably as a result of t(8,14) chromosome translocation. In this report, we described an unusual case of B-lymphoproliferative disorder with villous lymphocytes harboring t(8;14)(q24;q32) translocation, which could provide help in the diagnosis and differential diagnosis of B-lymphocytic proliferative diseases.

Hairy cell leukaemia variant with periarticular joint infiltration and excellent radiotherapy response

Hairy cell leukaemia (HCL) is rare, accounting for only 2% of leukaemias. An even more infrequent variant has been described, HCL-V. The clinicopathologic features of these two entities overlap significantly, although they differ in a number of aspects, including demographics and immunophenotype. In this report, we present the case of a man with HCL-V diagnosed 12 years previously, who is currently haematologically stable with an unusual complication of joint pain due to extensive bony expansion secondary to leukaemic infiltration, and atypical skeletal imaging. His painful joint disease responded dramatically to radiotherapy.

Hairy Cell Lymphoma: A Potentially Under-Recognized Entity

Hairy cell leukemia (HCL) is a low grade B-cell lymphoproliferative disorder that typically presents with splenomegaly, cytopenias, and diffuse bone marrow infiltration. There have been few cases in the literature of HCL presenting as lymphomas in extra-nodal locations, such as soft tissues and bones without circulating leukemic cells, splenomegaly, or iliac crest bone marrow involvement. We present an additional case presenting as a thoracic mass, and discuss potential diagnostic pitfalls and management of these rare cases.

A 80-Year-Old Woman with B-Cell Prolymphocytic Leukemia

Prolymhocytic leukemia (PLL) is a rare subtype of lymphocytic leukemias and its cells are immature lymphocytes. It is divided into 2 subgroups: T-PLL and B-PLL according to the lymphocytic origin of the cells. Discriminating B-PLL from other diseases with clinically-similar features is important because of the different treatment approaches and follow-up programs. Hereby, we report a 80-year-old woman presenting with fatigue, leucocytosis and mild anemia. Her peripheral blood smear evaluation revealed 85% prolymphocytes with moderately condensed nuclear chromatin, prominent nucleoli, and a faintly basophilic cytoplasm. Positron emission tomography-computed tomography showed mediastinal lymph nodes with cervical lymph nodes. There was no pathological FDG involvement in the spleen. Bone marrow aspiration smear exhibit atypical wide lymphocytes with prominent nucleoli and abundant agranular cytoplasm. Flow cytometry analysis revealed positive CD5⁺, CD19⁺, CD20⁺, CD22⁺, CD11c⁺, CD25⁺, CD79a⁺ and CD79b⁺. Fluorescence in situ hybridization technique analysis reveals no t(11;14). Bone marrow biopsy revealed interstitially distributed atypical cells with wide nucleus and prominent nucleolus.

Splenic marginal zone lymphoma

Splenic marginal zone lymphoma (SMZL) is an indolent small B-cell lymphoma involving the spleen and bone marrow characterized by a micronodular tumoral infiltration that replaces the preexisting lymphoid follicles and shows marginal zone differentiation as a distinctive finding. SMZL cases are characterized by prominent splenomegaly and bone marrow and peripheral blood infiltration. Cells in peripheral blood show a villous cytology. Bone marrow and peripheral blood characteristic features usually allow a diagnosis of SMZL to be performed. Mutational spectrum of SMZL identifies specific findings, such as 7q loss and NOTCH2 and KLF2 mutations, both genes related with marginal zone differentiation. There is a striking clinical variability in SMZL cases, dependent of the tumoral load and performance status. Specific molecular markers such as 7q loss, p53 loss/mutation, NOTCH2 and KLF2 mutations have been found to be associated with the clinical variability. Distinction from Monoclonal B-cell lymphocytosis with marginal zone phenotype is still an open issue that requires identification of precise and specific thresholds with clinical meaning.

A Unique Hairy Cell Leukemia Variant

A 65-year-old woman presented with easy bruising, left upper quadrant pain, decreased appetite, and weight loss. She had splenomegaly and lymphocytosis (lymphocyte count of 11.6 × 10(9)/l), with remarkably abnormal appearing morphology. Her hemoglobin and platelet counts were normal. Peripheral blood flow cytometry revealed a monoclonal B-cell population expressing CD11c, CD25, CD19, CD20, and CD103. An initial diagnosis of hairy cell leukemia (HCL) was made, and the patient was treated with a standard 5-day course of cladribine. However, her lymphocytosis improved transiently, with a relapse 4 months later. There was no improvement in her splenomegaly. An HCL variant (HCL-v) was considered based on her resistance to treatment with a purine nucleoside analog. A subsequent splenectomy improved symptoms. Two years after, the patient suffered a relapse and underwent 6 cycles of CHOP-R (cyclophosphamide, hydroxydaunomycin, oncovin, prednisone, and rituximab), achieving partial remission. While under observation, she progressed with lymphocytosis 6 months later and was treated with pentostatin. There was no significant improvement in her disease, and she died 8 weeks following treatment initiation. HCL-v is a clinically more aggressive mature B-cell lymphoma than HCL with worse splenomegaly, higher lymphocyte counts, and resistance to typical HCL therapy with purine nucleoside analogs. Early recognition of HCL-v in the history, physical examination, and investigations with morphology and flow cytometry is key to patient management. Further, as in our case of HCL-v, cell morphology can be distinctly atypical, with large nucleoli and extremely convoluted nuclei. The distinction between HCL and HCL-v is important as HCL-v patients require more aggressive therapy and closer follow-up.

Long-term durable remission by cladribine followed by rituximab in patients with hairy cell leukaemia: update of a phase II trial

Nucleoside analogues are highly active in patients with hairy cell leukaemia (HCL); however, patients continue to relapse. This phase II study evaluated the efficacy and safety of cladribine followed by rituximab in patients with untreated HCL (N = 59), relapsed HCL (N = 14) and HCL variant (HCLv, N = 7). Cladribine 5·6 mg/m(2) was given intravenously (IV) daily for 5 d and was followed approximately 1 month later with rituximab 375 mg/m(2) IV weekly for 8 weeks. Complete response rate in patients with untreated HCL, relapsed HCL and HCLv was 100%, 100% and 86%, respectively. With a median follow up of 60 months, 5-year failure-free survival (FFS) in patients with untreated HCL, relapsed HCL and HCLv was 95%, 100% and 64%, respectively. Median duration of response to the cladribine followed by rituximab was significantly longer than the first-line cladribine single agent in patients who received this treatment as second-line treatment (72 months vs not reached, P = 0·004). Almost all patients (94%) achieved negative minimal residual disease (MRD) after the treatment. Positive MRD during the follow up did not necessarily result in clinically relevant relapse. Cladribine followed by rituximab is highly effective even in patients with relapsed disease and HCLv, and can achieve durable remission.

Issues in diagnosis of small B cell lymphoid neoplasms involving the bone marrow and peripheral blood. Report on the Bone Marrow Workshop of the XVIIth meeting of the European Association for Haematopathology and the Society for Hematopathology

Small B cell lymphoid neoplasms are the most common lymphoproliferative disorders involving peripheral blood (PB) and bone marrow (BM). The Bone Marrow Workshop (BMW) organized by the European Bone Marrow Working Group (EBMWG) of the European Association for Haematopathology (EAHP) during the XVIIth EAHP Meeting in Istanbul, October 2014, was dedicated to discussion of cases illustrating how the recent advances in immunophenotyping, molecular techniques and cytogenetics provide better understanding and classification of these entities. Submitted cases were grouped into following categories: (i) cases illustrating diagnostic difficulties in chronic lymphocytic leukaemia (CLL); (ii) cases of BM manifestations of small B cell lymphoid neoplasms other than CLL; (iii) transformation of small B cell lymphoid neoplasms in the BM; and (iv) multiclonality and composite lymphomas in the BM. This report summarizes presented cases and conclusions of the BMW and provides practical recommendations for classification of the BM manifestations of small B cell lymphoid neoplasms based on the current state of knowledge.

CD5 positive hairy cell leukemia: A rare case report with brief review of literature

OBJECTIVE

The aberrant expression of CD5 in both HCL and HCL-v is a very rare event. Although a number of CD5 positive HCL and HCL-v cases have been reported, but these are far and few in between. We aimed to review the reported cases of CD5 positive HCL and its variant.

METHOD

We hereby report a case of CD5 positive HCL, with variations in PIK3CA and PDGFRA gene, along with a brief review of literature of the cases of CD5 positive HCL and its variant.

RESULTS AND CONCLUSION

The current case was positive for CD103, CD11c, CD25, and CD123 which has led the diagnosis to be of typical HCL. With the extensive literature review we found that only 26 cases of hairy cell leukemia [HCL and HCL-v] bearing CD5 expression have been reported so far. The positivity of CD5 is more common in HCL-v as compared to HCL. Additional prospective studies of CD5+ HCL and its variants are required to show whether they are a clinically significant subgroup of lymphoid malignancies. © 2016 International Clinical Cytometry Society.

Splenic marginal zone lymphoma: from genetics to management

Splenic marginal zone lymphoma (SMZL) is a rare B-cell malignancy involving the spleen, bone marrow, and frequently the blood. SMZL lymphomagenesis involves antigen and/or superantigen stimulation and molecular deregulation of genes (NOTCH2 and KLF2) involved in the physiological differentiation of spleen marginal zone B cells. Diagnosis requires either spleen histology or, alternatively, the documentation of a typical cell morphology and immunophenotype on blood cells coupled with the detection of intrasinusoidal infiltration by CD20+ cells in the bone marrow. Among B-cell tumors, deletion of 7q and NOTCH2 mutations are almost specific lesions of SMZL, thus representing promising diagnostic biomarkers of this lymphoma. Although the majority of SMZLs show an indolent course with a median survival of approximately 10 years, nearly 30% of patients experience a poor outcome. No randomized trials are reported for SMZL, and few prospective trials are available. A watch-and-wait approach is advisable for asymptomatic patients. Treatment options for symptomatic patients ranges from splenectomy to rituximab alone or combined with chemotherapy. In some geographic areas, a subset of patients with SMZL associates with hepatitis C virus infection, prompting virus eradication as an effective lymphoma treatment. It would be worthwhile to explore deregulated cellular programs of SMZL as therapeutic targets in the future; improved clinical and biological prognostication will be essential for identifying patients who may benefit from novel approaches.

Immunoconjugates in the management of hairy cell leukemia

Hairy cell leukemia (HCL) is an indolent B-cell malignancy effectively treated but not often cured by purine analog therapy; after multiple courses of purine analogs, patients can become purine analog resistant and in need of alternative therapies. Complete remission to single-agent purine analog is often accompanied by minimal residual disease (MRD), residual HCL cells detectable by immunologic methods, considered a risk factor for eventual relapse. Several different non-chemotherapy approaches are being used to target relapsed and refractory HCL, including inhibitors of BRAF, but so far only monoclonal antibody (MAb)-based approaches have been reported to eliminate MRD in a high percentage of patients. One of the MAb-based options for HCL currently under clinical investigation involves recombinant immunotoxins, containing a fragment of a MAb and a bacterial toxin. The bacterial toxin, a highly potent fragment from Pseudomonas exotoxin, catalytically ADP-ribosylates elongation factor 2 (EF2), resulting in protein synthesis inhibition and apoptotic cell death. Recombinant immunotoxins tested in HCL patients include LMB-2, targeting CD25, and BL22, targeting CD22. An affinity matured version of BL22, termed moxetumomab pasudotox (formerly HA22 or CAT-8015) achieved high CR rates in phase I, and is currently undergoing multicenter Phase 3 testing. Phase I testing was without dose-limiting toxicity, although 2 patients had grade 2 hemolytic uremic syndrome (HUS) with transient grade 1 abnormalities in platelets and creatinine. Preclinical work is underway to identify residues on moxetumomab pasudotox leading to immunogenicity. Moxetumomab pasudotox is undergoing pivotal testing for relapsed and refractory HCL.

Bone marrow and splenic histology in hairy cell leukaemia

Hairy cell leukaemia is a rare chronic neoplastic B-cell lymphoproliferation that characteristically involves blood, bone marrow and spleen with liver, lymph node and skin less commonly involved. Histologically, the cells have a characteristic appearance with pale/clear cytoplasm and round or reniform nuclei. In the spleen, the infiltrate involves the red pulp and is frequently associated with areas of haemorrhage (blood lakes). The cells stain for B-cell related antigens as well as with antibodies against tartrate-resistant acid phosphatase, DBA44 (CD72), CD11c, CD25, CD103, CD123, cyclin D1 and annexin A1. Mutation of BRAF -V600E is present and antibody to the mutant protein can be used as a specific marker. Bone marrow biopsy is essential in the initial assessment of disease as the bone marrow may be inaspirable or unrepresentative of degree of marrow infiltration as a result of the tumour associated fibrosis preventing aspiration of the tumour cell component. Bone marrow biopsy is important in the assessment of therapy response but in this context staining for CD11c and Annexin A1 is not helpful as they are also markers of myeloid lineage and identification of low level infiltration may be obscured. In this context staining for CD20 may be used in conjunction with morphological assessment and staining of serial sections for cyclin D1 and DBA44 to identify subtle residual infiltration. Staining for CD79a and CD19 is not recommended as these antibodies will identify plasma cells and can lead to over-estimation of disease. Staining for CD20 should not be used in patients following with anti-CD20 based treatments. Down regulation of cyclin D1 and CD25 has been reported in patients following BRAF inhibitor therapy and assessment of these antigens should not be used in this context. Histologically, hairy cell leukaemia needs to be distinguished from other B-cell lymphoproliferations associated with splenomegaly including splenic marginal zone lymphoma, splenic diffuse red pulp small B-cell lymphoma and hairy cell leukaemia variant. This can be done by assessment of the spleen but as this is now rarely performed in this disorder distinction is almost always possible by a combination of morphological and immunophenotypic studies on bone marrow trephine biopsy, which can be supplemented by assessment of BRAF-V600E mutation assessment in borderline cases.

Hairy cell leukaemia-variant: Disease features and treatment

Hairy cell leukaemia-variant (HCL-V) is a rare B-cell malignancy that affects elderly males and manifests with splenomegaly, lymphocytosis and cytopenias without monocytopenia. The neoplastic cells have morphological features of prolymphocytes and hairy cells. The immunophenotype is that of a clonal B-cell CD11c and CD103 positive but, unlike classical HCL, CD25, CD123 and CD200 negative. The spleen histology is similar to classical HCL and the pattern of bone marrow infiltration is interstitial and/or intrasinusoidal. Mutations of the immunoglobulin heavy chain (IGVH) are seen in two thirds of cases with a preferential VH4-34 family usage. There is no distinct chromosomal abnormality but del17p13 and mutations of the TP53 gene are frequent. Mutations in the MAP2K1 gene have been documented in half of the cases. The course is chronic with median survivals of 7-9 years. Patients are refractory to purine analogues and the most effective therapy is the combination of 2-chlorodeoxyadenosine and Rituximab.

Impact of telomere length on survival in classic and variant hairy cell leukemia

Telomeres, which protect the ends of chromosomes, are shortened in several hematologic malignancies, often with adverse prognostic implications, but their effect on prognosis of classic and variant hairy cell leukemia (HCL and HCLv) has not been reported. HCL/HCLv genomic DNA from 46 patients was studied by PCR to determine the ratio of telomere to single copy gene number (T/S). T/S was unrelated to diagnosis of HCL or HCLv (p=0.27), but shorter T/S was associated with unmutated immunoglobulin rearrangements (p=0.033) and age above the median at diagnosis (p=0.017). Low T/S was associated with shorter overall survival from diagnosis (OS), particularly T/S <0.655 (p=0.0064, adjusted p=0.019). Shorter OS was also associated with presence of unmutated (p<0.0001) or IGHV4-34+ (p<0.0001) rearrangements, or increasing age (p=0.0002). Multivariable analysis with Cox modeling showed that short T/S along with either unmutated or IGHV4-34+ rearrangements remained associated with reduced OS (p=0.0071, p=0.0024, respectively) after age adjustment. While T/S is relatively long in HCL and the disease usually indolent with excellent survival, shortened telomeres in HCL/HCLv are associated with decreased survival. Shortened T/S could represent a risk factor needing further investigation/intervention to determine if non-chemotherapy treatment options, in addition to or instead of chemotherapy, might be particularly useful.

A 2015 update on predictive molecular pathology and its role in targeted cancer therapy: a review focussing on clinical relevance

In April 2013 our group published a review on predictive molecular pathology in this journal. Although only 2 years have passed many new facts and stimulating developments have happened in diagnostic molecular pathology rendering it worthwhile to present an up-date on this topic. A major technical improvement is certainly given by the introduction of next-generation sequencing (NGS; amplicon, whole exome, whole genome) and its application to formalin-fixed paraffin-embedded (FFPE) tissue in routine diagnostics. Based on this 'revolution' the analyses of numerous genetic alterations in parallel has become a routine approach opening the chance to characterize patients' malignant tumors much more deeply without increasing turn-around time and costs. In the near future this will open new strategies to apply 'off-label' targeted therapies, e.g. for rare tumors, otherwise resistant tumors etc. The clinically relevant genetic aberrations described in this review include mutation analyses of RAS (KRAS and NRAS), BRAF and PI3K in colorectal cancer, KIT or PDGFR alpha as well as BRAF, NRAS and KIT in malignant melanoma. Moreover, we present several recent advances in the molecular characterization of malignant lymphoma. Beside the well-known mutations in NSCLC (EGFR, ALK) a number of chromosomal aberrations (KRAS, ROS1, MET) have become relevant. Only very recently has the clinical need for analysis of BRCA1/2 come up and proven as a true challenge for routine diagnostics because of the genes' special structure and hot-spot-free mutational distribution. The genetic alterations are discussed in connection with their increasingly important role in companion diagnostics to apply targeted drugs as efficient as possible. As another aspect of the increasing number of druggable mutations, we discuss the challenges personalized therapies pose for the design of clinical studies to prove optimal efficacy particularly with respect to combination therapies of multiple targeted drugs and conventional chemotherapy. Such combinations would lead to an extremely high complexity that would hardly be manageable by applying conventional study designs for approval, e.g. by the FDA or EMA. Up-coming challenges such as the application of methylation assays and proteomic analyses on FFPE tissue will also be discussed briefly to open the door towards the ultimate goal of reading a patients' tissue as 'deeply' as possible. Although it is yet to be shown, which levels of biological information are most informative for predictive pathology, an integrated molecular characterization of tumors will likely offer the most comprehensive view for individualized therapy approaches. To optimize cancer treatment we need to understand tumor biology in much more detail on morphological, genetic, proteomic as well as epigenetic grounds. Finally, the complex challenges on the level of drug design, molecular diagnostics, and clinical trials make necessary a close collaboration among academic institutions, regulatory authorities and pharmaceutical companies.

Immunohistochemistry for BRAF V600E in the Differential Diagnosis of Hairy Cell Leukemia vs Other Splenic B-Cell Lymphomas

OBJECTIVES

Recent reports have used immunohistochemistry (IHC) with a mutation-specific antibody to detect the BRAF V600E mutation, which is found in nearly all cases of hairy cell leukemia (HCL). To date, however, only a small number of non-HCL, splenic B-cell lymphomas have been examined by IHC.

METHODS

We analyzed 121 cases, including 26 HCLs, 52 non-HCL splenic lymphomas, 22 chronic lymphocytic leukemias/small lymphocytic lymphomas (CLLs/SLLs), and 21 plasma cell neoplasms (PCNs) for BRAF V600E expression by IHC. Molecular testing for BRAF V600E was performed in a subset of cases, using allele-specific polymerase chain reaction and/or Sanger sequencing.

RESULTS

Twenty-six (100%) of 26 HCL cases were positive by IHC vs one (1%) of 95 non-HCL cases. Positive staining was identified in one (2%) of 44 splenic marginal zone lymphomas (SMZLs), while each of 22 CLLs/SLLs, 21 PCNs, six unclassifiable splenic lymphomas, and two HCL variants were negative. IHC and molecular results were concordant in all cases examined (21 HCLs and 21 non-HCLs, including the BRAF+ SMZLs).

CONCLUSIONS

The detection of BRAF V600E by IHC is useful in the distinction of HCLs from other splenic-based lymphomas, although the identification of at least rare SMZLs containing this abnormality illustrates the continuing need for a multiparameter approach to diagnosis.

Diagnosis of Splenic B-Cell Lymphomas in the Bone Marrow: A Review of Histopathologic, Immunophenotypic, and Genetic Findings

Splenic B-cell lymphomas are a heterogeneous group of diseases comprising several entities that exhibit overlapping features. Diagnosis of these lymphomas has been reliant on the histopathologic examination of the spleen. However, with advances in diagnostic modalities and therapy, splenectomy is not commonly performed, and diagnosis and subclassification must be rendered based on the blood and bone marrow findings. In this brief review, we summarize the morphologic, immunophenotypic, and genetic findings of splenic B-cell lymphomas in the blood and bone marrow.

Recommendations of the SFH (French Society of Haematology) for the diagnosis, treatment and follow-up of hairy cell leukaemia

Hairy cell leukaemia (HCL) is a rare haematological malignancy, with approximately 175 new incident cases in France. Diagnosis is based on a careful examination of the blood smear and immunophenotyping of the tumour cells, with a panel of four markers being used specifically to screen for hairy cells (CD11c, CD25, CD103 and CD123). In 2011, the V600E mutation of the BRAF gene in exon 15 was identified in HCL; being present in HCL, it is absent in the variant form of HCL (HCL-v) and in splenic red pulp lymphoma (SRPL), two entities related to HCL. The management of patients with HCL has changed in recent years. A poorer response to purine nucleoside analogues (PNAs) is observed in patients with more marked leukocytosis, bulky splenomegaly, an unmutated immunoglobulin variable heavy chain (IgVH) gene profile, use of VH4–34 or with TP53 mutations. We present the recommendations of a group of 11 experts belonging to a number of French hospitals. This group met in November 2013 to examine the criteria for managing patients with HCL. The ideas and proposals of the group are based on a critical analysis of the recommendations already published in the literature and on an analysis of the practices of clinical haematology departments with experience in managing these patients. The first-line treatment uses purine analogues: cladribine or pentostatin. The role of BRAF inhibitors, whether or not combined with MEK inhibitors, is discussed. The panel of French experts proposed recommendations to manage patients with HCL, which can be used in a daily practice.

Hairy cell leukemia-new genes, new targets

Hairy cell leukemia (HCL), a B cell malignancy comprising 2 % of all leukemias, has become quite exciting recently with regard to the development of new targets for therapy. This review will focus on advancements made within the past 1-2 years in targeted therapy for this disease. These advances may be grouped into two very difference categories, namely targeting of CD22 with the recombinant immunotoxin moxetumomab pasudotox, and targeting of the mutated BRAF component of the MAP kinase pathway. Moxetumomab pasudotox in phase I testing was recently reported to be associated with an overall response rate of 86 % and a complete remission (CR) rate of 46 % in 28 patients with relapsed and refractory HCL. Many of the CRs are without minimal residual disease (MRD). Severe or dose limiting toxicity was not observed on this trial, but a completely reversible and largely asymptomatic form of grade 2 hemolytic uremic syndrome occurred in two patients during retreatment. This agent has commenced phase III multicenter testing to validate its phase I results. An extensive number of studies have documented the V600E mutation in nearly all HCL patients, but not in similar hematologic malignancies. The thymidine kinase inhibitor vemurafenib, which inhibits the V600E mutant of BRAF, was reported to induce a CR in multiply relapsed and refractory HCL, with nearly complete clearing of MRD. One additional partial and one additional complete remission were subsequently reported.

Splenic marginal zone B-cell lymphoma: a distinct clinicopathological and molecular entity. Recent advances in ontogeny and classification

PURPOSE OF REVIEW

Indolent B-cell lymphomas that are supposed to derive from marginal zone encompass three distinct entities: extranodal marginal zone lymphoma (MZL) or mucosa-associated lymphatic tissue (MALT), nodal MZL (NMZL) and splenic MZL (SMZL). Although MALT lymphoma is well characterized and extensively studied at the clinical and molecular levels, SMZL and NMZL remain incompletely characterized. However, during the last years, the clinical and molecular heterogeneity of SMZL has been clarified. The recent 2008 WHO classification has maintained the distinction between the three diseases according to the organ where it arises and introduced a new provisional category of unclassified splenic lymphoma for overlapping entities, splenic diffuse red pulp lymphoma (SDRPL) and hairy cell leukemia-variant (HCL-V).

RECENT FINDINGS

Recent findings in SMZL contributed to a better characterization, including the few cases associated with hepatitis C, the recurrence of 7q deletion and the possibility of CD5 expression. Furthermore, the peculiar pattern of immunoglobulin heavy chain genes mutations and the biased usage of immunoglobulin heavy chain variable region genes (IGHV)1-2 segment are suggestive of a T-independent antigen driven proliferation, at least at initial steps. This review will focus on recent findings and differential diagnosis with SDRPL and HCL-V.

SUMMARY

The conjunction of morphologic, cytogenetic and clinical data has increased diagnosis reproducibility.

A hairy cell leukaemia variant - a rare case report

The aim of the article is to present a rare case of Hairy cell leukaemia variant (HCl-V) which is a distinct clinico-pathological entity with intermediate features between classical HCl (HCl-C) and B-cell prolymphocytic leukaemia. It is an uncommon disorder accounting for approximately 0.4% of chronic lymphoid malignancies and 10% of all HCl cases. A 58 year old woman presented with pain abdomen and loss of weight. On examination she had massive splenomegaly. Peripheral smear was reported as chronic lymphoproliferative disorder (? Hairy cell leukemia or splenic lymphoma with villous lymphocytes). On Bone marrow examination, differential diagnosis was given as splenic lymphoma with villous lymphocytes (SLVL) and prolymphocytic variant of Hairy cell leukemia. On flow cytometric analysis, these cells were positive for CD11c, CD19, CD20, and CD22. Based on the clinical, peripheral smear, bone marrow and flow cytometry findings, a diagnosis of hairy cell leukaemia variant was confirmed. The differential diagnosis should always include SLVL, HCL-C and Japanese variant HCL because they have different clinical and biological features, particularly regarding their response to purine analogue-based treatment or splenectomy.

Distinguishing hairy cell leukemia variant from hairy cell leukemia: development and validation of diagnostic criteria

Hairy cell leukemia (HCL) and hairy cell leukemia-variant (HCL-v) are rare diseases with overlapping clinico-pathological features. We performed flow cytometry analysis (FCM) of 213 cases (169 HCL, 35 HCL-v, 9 splenic marginal zone lymphoma (SMZL)), correlating results with available corresponding clinical and morphological data. FCM distinguished HCL-v from HCL and SMZL based solely upon expression of four antigens (CD11c, CD25, CD103, CD123) combined with B-cell markers (CD19, CD20, CD22). HCL-v expressed bright CD20, bright CD22, CD11c(100%), CD103(100%), dim(40%) or negative(60%) CD123, and uniformly lacked CD25(100%). HCL expressed bright CD20, bright CD22, bright CD11c, bright CD25, CD103, and bright homogeneous CD123(100%). Aberrant expression of CD5(2%/3%), CD10(12%/3%), CD23(21%/11%), CD38(14%/0%), CD2(2%/9%), CD4(0.5%/0%) and CD13(0.5%/3%), was observed in HCL/HCL-v, respectively. SMZL cases were CD103(-) and CD123(-) except for one case with dim CD123. HCL showed significantly greater marrow infiltration over HCL-v. Prominent nucleoli were observed in most HCL-v but rarely in HCL. A third of HCL and HCL-v marrows were hypocellular or aplastic-appearing. Detection of BRAFV600E mutation and annexin A1 were examined in a subset of cases to further validate FCM diagnostic criteria. HCL-v was negative for both annexin A1 (100%) and BRAFV600E mutation (100%), in contrast to HCL (74% positive for annexin A1; 76% positive for BRAFV600E mutation). HCL-v is resistant to traditional HCL therapy, making accurate diagnosis imperative. We have defined FCM criteria for differentiation of HCL-v from HCL and SMZL.

Extranodal and splenic small B-cell lymphoma

Although almost any non-Hodgkin lymphoma can involve the spleen or an extranodal site as part of more widely disseminated disease, there is a group of small B-cell lymphomas that specifically arise in these locations. These are important to recognise as some appear to have a behaviour and prognosis that is distinct from their nodal counterparts. In addition, there are entities that are specific to extranodal locations (such as extranodal marginal zone lymphoma) and to the red or white pulp of the spleen. In this review, the characteristics of these entities will be presented as well as clues to help distinguish lymphoma from reactive infiltrates in extranodal sites and measure to distinguish between small B-cell lymphomas encountered in the spleen and at extranodal locations.

Molecular variant of hairy cell leukemia with poor prognosis

Hairy cell leukemia variant (HCLv), described 30 years ago, was reported to present with high disease burden and less often leukopenia, and later was reported to be resistant to purine analogs. Patients with HCLv were overrepresented among patients with HCL seeking relapsed/refractory trials. To compare clinical and molecular features of classic HCL (HCLc) and HCLv, 85 rearrangements expressing immunoglobulin variable heavy chain were sequenced, taken from 20 patients with HCLv and 62 with HCLc. The gene VH4-34, commonly used in autoimmune disorders, was found in eight patients (40%) with HCLv versus six (10%) with HCLc (p = 0.004). Ninety-three percent of the VH4-34 rearrangements were unmutated, defined as >98% homologous to the germline sequence. Clinical features of VH4-34+ patients that were similar to those with HCLv included higher white blood cell counts at diagnosis (p = 0.002) and lower response (p = 0.00001) and progression-free survival (p = 0.007) after first-line cladribine, and shorter overall survival from diagnosis (p < 0.0001). It was found that VH4-34 was independent from HCLv and a stronger predictor than HCLv in associating with poor prognosis. We conclude that VH4-34+ hairy cell leukemia, which only partly overlaps with HCLv, is associated with poor prognosis after single-agent cladribine. However, cases are observed which respond well to antibody therapy either alone or in combination with purine analog.

Classical hairy cell leukemia and its variant: a 17-year retrospective survey in Taiwan Chinese

BACKGROUND

Classical hairy cell leukemia (HCL-C) and its variant (HCL-V) are rare chronic B-cell lymphoproliferative disorders. Only a few reports in Chinese patients are available.

METHODS

We retrospectively reviewed 16 patients with HCL-C and HCL-V in Taiwan over a 17-year period.

RESULTS

Eight were HCL-C and 8 were HCL-V. All HCL accounted for 0.7% of all adult leukemias. Compared to HCL-V, HCL-C was characterized by profound leukopenia, monocytopenia, thrombocytopenia and fewer circulating hairy cells. One HCL-C and 2 HCL-V patients had second malignancies. Seven HCL-C patients achieved hematological remission after splenectomy (n = 1) or 2-chlorodeoxyadenosine (n = 6). Of the 8 HCL-V patients, 6 received splenic irradiation. Only one achieved complete remission and another had partial remission; relapse or disease progression was noted 13.4 or 25.7 months later, respectively. Two of three HCL-V patients who underwent splenectomy had stable disease. All patients with HCL-C were alive while 3 with HCL-V expired. Compared to HCL-C, HCL-V had a significantly shorter leukemia-free survival.

CONCLUSION

A relatively higher proportion of HCL-V in all HCL comparing to Westerners is observed. Second malignancies are common. With an inferior outcome and dismal response to most treatment, enrollment in a clinical trial should be considered for HCL-V.

Splenic B-Cell Lymphomas/Leukemias

The diagnosis and classification of lymphoproliferative disorders in the spleen are frequently challenging. While some lymphomas, such as hairy cell leukemia and splenic marginal zone lymphoma, characteristically present with primarily splenic involvement, secondary involvement of the spleen may be seen with any lymphoma. Precise classification requires integration of the morphologic findings with clinical data, phenotypic studies, and often cytogenetic and/or molecular genetic analysis. Correlation with the findings in peripheral blood and bone marrow may also be required in some cases. This article discusses the diagnostic approach to splenic-based lymphoproliferative disorders in routine practice and describes the clinicopathologic features of lymphoid neoplasms that characteristically present in the spleen.

How I diagnose and treat splenic lymphomas

The incidental finding of an isolated splenomegaly during clinical assessment of patients evaluated for unrelated causes has become increasingly frequent because of the widespread use of imaging. Therefore, the challenging approach to the differential diagnosis of spleen disorders has emerged as a rather common issue of clinical practice. A true diagnostic dilemma hides in distinguishing pathologic conditions primarily involving the spleen from those in which splenomegaly presents as an epiphenomenon of hepatic or systemic diseases. Among the causes of isolated splenomegaly, lymphoid malignancies account for a relevant, yet probably underestimated, number of cases. Splenic lymphomas constitute a wide and heterogeneous array of diseases, whose clinical behavior spans from indolent to highly aggressive. Such a clinical heterogeneity is paralleled by the high degree of biologic variation in the lymphoid populations from which they originate. Nevertheless, the presenting clinical, laboratory, and pathologic features of these diseases often display significant overlaps. In this manuscript, we present our approach to the diagnosis and treatment of these rare lymphomas, whose complexity has been so far determined by the lack of prospectively validated prognostic systems, treatment strategies, and response criteria.