Real-world data on diagnostics, treatment and outcomes of patients with hairy cell leukemia: The HCL-CLLEAR study.

Hairy cell leukemia (HCL) and HCL-like disorders have to be distinguished because of their different biology and treatment response. Thus, we conducted a retrospective study on patients with HCL and hairy cell leukemia variant (HCLv) to assess diagnostic algorithms and treatment outcomes in a real-world setting. We analyzed 225 HCL and 26 HCLv patients with median follow-up of 67.9 months (HCL) and 20.1 months (HCLv). Median age at diagnosis was 56.2 (HCL) and 69.5 years (HCLv), male predominance was observed in both groups (76.0% vs. 73.1%). Diagnostics was mostly based on morphological evidence of hairy cells in the peripheral blood and bone marrow. At diagnosis, BRAF V600E mutation was detected in 94.7% of examined HCL patients and in no HCLv patient. Front-line treatment was indicated in 205 (91.1%) HCL and 18 (69.2%) HCLv patients. The majority of HCL patients were administered a cladribine-based regimen (91.2%). Overall response rate (ORR) was higher in cladribine-treated patients compared to those given other treatments (97.7% vs. 81.3%), the same applied with achieving Complete remission (CR) (91.2% vs. 62.5%). HCLv treatment was heterogeneous, but cladribine remained the most frequent option (44.4%) with ORR 81.3% and CR rates 43.8%. Second-line treatment was indicated in 52 HCL and 8 HCLv patients, 25.4% and 44.4% of those treated in first-line. In the whole HCL group, median time to next treatment (TTNT) was not reached and 10-year TTNT was estimated at 74.1%. HCLv patients who underwent first-line treatment had a median TTNT of 56 months. The median overall survival (OS) in HCL patients was not reached compared to HCLv with a median OS of 9.5 years. These data confirm an excellent prognosis for HCL patients treated with cladribine-based therapy. On the contrary, HCLv with its aggressive behavior represents a group of patients in whom novel treatment approaches are needed.

Hairy cell leukemia 2024: Update on diagnosis, risk-stratification, and treatment-Annual updates in hematological malignancies.

DISEASE OVERVIEW: Hairy cell leukemia (HCL) and HCL-like disorders, including HCL variant (HCL-V) and splenic diffuse red pulp lymphoma (SDRPL), are a very heterogenous group of mature lymphoid B-cell disorders characterized by the identification of hairy cells, a specific genetic profile, a different clinical course and the need for appropriate treatment. DIAGNOSIS: Diagnosis of HCL is based on morphological evidence of hairy cells, an HCL immunologic score of 3 or 4 based on the CD11c, CD103, CD123, and CD25 expression, the trephine biopsy which makes it possible to specify the degree of tumoral bone marrow infiltration and the presence of BRAFV600E somatic mutation. RISK STRATIFICATION: Progression of patients with HCL is based on a large splenomegaly, leukocytosis, a high number of hairy cells in the peripheral blood, and the immunoglobulin heavy chain variable region gene mutational status. VH4-34 positive HCL cases are associated with a poor prognosis, as well as HCL with TP53 mutations and HCL-V. TREATMENT: Patients should be treated only if HCL is symptomatic. Chemotherapy with risk-adapted therapy purine analogs (PNAs) are indicated in first-line HCL patients. The use of chemo-immunotherapy combining cladribine (CDA) and rituximab (R) represents an increasingly used therapeutic approach. Management of relapsed/refractory disease is based on the use of BRAF inhibitors (BRAFi) plus R, MEK inhibitors (MEKi), recombinant immunoconjugates targeting CD22, Bruton tyrosine kinase inhibitors (BTKi), and Bcl-2 inhibitors (Bcl-2i). However, the optimal sequence of the different treatments remains to be determined.

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.

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.

Hairy cell leukaemia with unusual BRAF mutations.

Hairy cell leukaemia (HCL) diagnosis is based on the morphologic detection of circulating abnormal hairy cells in the peripheral blood and/or bone marrow, an HCL immunological score of 3 or 4 based on the expression of the CD11c, CD25, CD103 and CD123 and also the presence of a BRAF V600E activating mutation in the B-raf proto-oncogene (BRAF gene) (7q34). When using new generation sequencing of 21 targeted genes in 124 HCL patients, we identified a cohort of 6/124 (2%) patients with unusual BRAF mutations: two patients presented non-V600 mutations (BRAF F595L, BRAF W604L respectively) and four other patients silent BRAF mutations. When using droplet digital PCR (ddPCR) three of the four patients with concomitant BRAF V600E and silent mutation were negative. The respective role of these mutations in the occurrence of HCL or its progression remains to be clarified, but BRAF sequencing is necessary in case of negative BRAF V600E by ddPCR.

A case report of early diagnosis of asymptomatic hairy cell leukemia using flow cytometry.

Hairy Cell Leukemia is an infrequent leukemia that can be recognized both microscopically and flow cytometrically once the patient develops symptoms. We present a case where early diagnosis was achieved using flow cytometry long before the patient became symptomatic. This was achieved by focusing on a small percentage (0.9%) of total leukocytes that exhibited a higher side scatter and brighter CD19/CD20 than the remaining lymphocytes. A bone marrow aspirate three weeks later confirmed the presence of malignant B-cells. Shortly after, the patient presented splenomegaly and complained of fatigue.

Flow Cytometry of CD5-Positive Hairy Cell Leukemia.

BACKGROUND AND OBJECTIVE: Hairy cell leukemia (HCL) is a chronic lymphoproliferative disorder for which diagnosis is typically straightforward, based on bone marrow morphology and flow cytometry (FC) or immunohistochemistry. Nevertheless, variants present atypical expressions of cell surface markers, as is the case of CD5, for which the differential diagnosis can be more difficult. The aim of the current paper was to describe diagnosis of HCL with atypical CD5 expression, with an emphasis on FC. METHODS: The detailed diagnostic methodology for HCL with atypical CD5 expression is presented, including differential diagnosis from other lymphoproliferative diseases with similar pathologic features, by FC analysis of the bone marrow aspirate. RESULTS: Diagnosis of HCL by means of FC started by gating all events based on side scatter (SSC) versus CD45 and B lymphocytes were selected from the lymphocytes gate as CD45/CD19 positive. The gated cells were positive for CD25, CD11c, CD20, and CD103, while CD10 proved to be dim to negative. Moreover, cells positive for CD3, CD4, and CD8, the three pan-T markers, as well as CD19, showed a bright expression of CD5. The atypical CD5 expression is usually correlated with a negative prognosis and thus chemotherapy with cladribine should be initiated. CONCLUSION: HCL is an indolent chronic lymphoproliferative disorder and diagnosis is usually straightforward. However, atypical expression of CD5 renders its differential diagnosis more difficult, but FC is a useful tool that allows an optimal classification of the disease and allows initiation of timely satisfactory therapy.

[Clinical and molecular characteristics and prognosis of classical hairy cell leukemia and hairy cell leukemia variant].

Objective: To evaluate the clinical characteristics, treatment response, and outcomes in patients with classical hairy cell leukemia (cHCL) and HCL variant (HCL-V). Methods: This is a retrospective case series study. Between January 2011 and December 2021, clinical data of 30 patients newly with diagnosed HCL at Peking Union Medical College Hospital were analyzed. The main outcome measures include clinical characteristics, treatment efficacy and survival. The Kaplan-Meier method was used for survival analysis. Results: Twenty-one cases of cHCL and 9 cases of HCL-v were included. The median age at diagnosis was 55.5 (range, 30-86) years, with the ratio of male to female 2.75∶1. The main clinical manifestations included fatigue in 11 cases (36.7%), abdominal distension in 7 cases (23.3%), and infection in 4 cases, while 8 cases were asymptomatic. Splenomegaly was reported in 24 cases (80.0%), including 7 (23.3%) with megalosplenia. The white blood cell count, lymphocyte count, and the proportion of peripheral hairy cells in HCL-v group were significantly higher than those in cHCL group, whereas the development of anemia, thrombocytopenia, and monocytopenia in cHCL group was more remarkable than that in HCL-v group (all P<0.05). The BRAF-V600E gene mutation was detected only in cHCL patients (11/14 vs. 0/9, P<0.001). In terms of immunophenotype, the expression of CD25, CD103, CD123 and CD200 in cHCL group (20/20, 20/20, 4/7, 7/17) were all stronger than those in HCL-v group (3/9, 7/9, 0/4, 2/8). Twenty-two patients were treated, of which 13 cases (12 cases of cHCL and 1 case of HCL-v) with cladribine, and 9 cases (4 cHCL and 5 HCL-v) with interferon. Complete remission rate and overall response rate were comparable between cladribine and interferon treatment groups (both P<0.05). The median follow-up time was 31 (range, 1-125) months, and the median overall survival (OS) of the entire group was 125 months. The 5-year OS rate in HCL-v patients represented a trend of inferior (50.0% vs. 95.0%, P=0.207). Conclusions: The clinical features of HCL are unspecific, which includes fatigue, splenomegaly and recurrent infection. The clinical features, immunophenotype, treatment response and prognosis of HCL-v are different from those of cHCL. BRAF-V600E gene mutation is suggested as a key marker for differential diagnosis. Cladribine is recommended as front-line regimen of cHCL patients with satisfactory efficacy and prognosis. Conversely, response and clinical outcome in HCL-v patients still need to be improved.

Hairy Cell Leukemia: Where Are We in 2023?

PURPOSE OF REVIEW: This article summarizes the current state of knowledge of hairy cell leukemia (HCL) regarding presentation, diagnosis, therapy, and monitoring, including perspectives on emergent therapies. RECENT FINDINGS: Over the past decade, there has been enormous progress in the understanding of the biology of HCL which has led to the development of novel therapeutic strategies. The maturation of data regarding existing management strategies has also lent considerable insight into therapeutic outcomes and prognosis of patients treated with chemo- or chemoimmunotherapy. Purine nucleoside analogs remain the cornerstone of treatment, and the addition of rituximab has deepened and prolonged responses in the upfront and relapsed setting. Targeted therapies now have a more defined role in the management of HCL, with BRAF inhibitors now having a potential in the first-line setting in selected cases as well as in relapse. Next-generation sequencing for the identification of targetable mutations, evaluation of measurable residual disease, and risk stratification continue to be areas of active investigation. Recent advances in HCL have led to more effective therapeutics in the upfront and relapsed setting. Future efforts will focus on identifying patients with high-risk disease who require intensified regimens. Multicenter collaborations are the key to improving overall survival and quality of life in this rare disease.

Long-term follow-up of patients with hairy cell leukemia in the south of Iran.

BACKGROUND: Hairy cell leukemia (HCL) is an indolent chronic lymphoproliferative disorder and first-line treatment with either intravenous or subcutaneous cladribine generally leads to long-lasting remissions. METHOD: All 131 patients with hairy-cell leukemia (HCL) were analyzed, with a median follow-up of 91 months. Data is from 2007 to 2020. We evaluated the response rate to cladribine as the first line and the response rate to cladribine with or without rituximab in relapsed patients. Further, we assessed relapse-free survival, complications, and secondary malignancy. RESULTS: After a median follow-up of 91 months, the recurrence rate was 24%. The 5-year and 10-year RFS rates were 85% and 66%, respectively. Adding rituximab to 2-CDA leads to a better response rate than just cladribine (90% vs. 27.3%, p-value = 0.002) in the relapsed patients. CONCLUSION: HCL patients have long-term survival when cladribine is the first line of treatment. Furthermore, adding rituximab to cladribine leads to a higher response rate.

Pulmonary damage in a patient with hairy cell leukemia - infectious involvement or hematological disease activity? Case report.

BACKGROUND: Hairy cell leukemia (HCL) is a rare indolent lymphoproliferative disease with an accumulation of mature B lymphocytes with fine reticular chromatin and cytoplasm with typical hairy-like cytoplasmic projections. Rarely, hairy cell leukemia manifests as a lung infiltration. The differential diagnosis between infection and malignant involvement with hairy cell leukemia is often challenging in such situations. METHODS AND RESULTS: We present a 53-year-old female with an uncommon pulmonary involvement with hairy cell leukemia. In addition, we discuss the complicated differential diagnosis of pulmonary disease in patients with hairy cell leukemia and the treatment approach to these patients. CONCLUSION: This case report describes the successful therapy management of a patient with pulmonary involvement by hairy cell leukemia. Therapy with interferon-alfa and cladribine resulted in long-term remission of the underlying disease.

Consensus opinion from an international group of experts on measurable residual disease in hairy cell leukemia.

A significant body of literature has been generated related to the detection of measurable residual disease (MRD) at the time of achieving complete remission (CR) in patients with hairy cell leukemia (HCL). However, due to the indolent nature of the disease as well as reports suggesting long-term survival in patients treated with a single course of a nucleoside analog albeit without evidence of cure, the merits of detection of MRD and attempts to eradicate it have been debated. Studies utilizing novel strategies in the relapse setting have demonstrated the utility of achieving CR with undetectable MRD (uMRD) in prolonging the duration of remission. Several assays including immunohistochemical analysis of bone marrow specimens, multi-parameter flow cytometry and molecular assays to detect the mutant BRAF V600E gene or the consensus primer for the immunoglobulin heavy chain gene (IGH) rearrangement have been utilized with few comparative studies. Here we provide a consensus report on the available data, the potential merits of MRD assessment in the front-line and relapse settings and recommendations on future role of MRD assessment in HCL.

Oncological management dilemma: a rare presentation of hairy cell leukaemia with hepatic involvement presenting concomitantly with pancreatic adenocarcinoma.

Hairy cell leukaemia (HCL) is a rare B cell malignancy that is associated with the BRAF V600E mutation and has good treatment response to purine analogues. Its presentation synchronously with other malignancies has been rarely reported. Here, we present a patient with HCL with hepatic involvement who was also found to have pancreatic adenocarcinoma concomitantly at the time of diagnosis. Treating these rare cases simultaneously is a challenge clinically. Throughout this case study, we provide our approach on how oncological care teams provided care for this complicated and rare disease state.

SYNCHRONOUS HAIRY CELL LEUKEMIA AND HEPATOCELLULAR CARCINOMA: A CASE REPORT.

Multiple primary malignant tumors are characterized by independent occurrence and development of two or more malignant neoplasms in the same patient. We present an extremely rare case of synchronous double primary malignancies, hairy cell leukemia and hepatocellular carcinoma with lethal outcome. Diagnosis of hepatocellular carcinoma was difficult due to the presence of lymphoproliferative disease, which complicated the visualization of the process using ultrasonography. Carcinomatous emboli of hepatocellular carcinoma in small pulmonary arteries without the formation of metastatic foci have led to clinical manifestations typical of pulmonary embolism, pulmonary hypertension and severe respiratory failure. In lymphoproliferative diseases it is necessary to take into account the possibility of the development of another malignant neoplasm, which can be "buried" by tumor infiltration.