Case report: Metastatic BRAF V600E-mutated adult Wilms' tumor with robust response to BRAF/MEK inhibitor therapy.

Nephroblastoma or Wilms' tumor (WT) is the most common pediatric renal malignancy but rare in adults. Treatment protocols for adults are typically extrapolated from pediatric guidelines, but there are no standard guidelines for adults due to the rarity of the disease. However, next-generation sequencing has led to new therapeutic options for adult WT patients. We present the first case to our knowledge of a recurrent adult WT treated with dual BRAF/MEK-targeted therapy, which showed initial robust clinical response and was well tolerated.

Real-world outcomes of stage II and III colorectal cancers treated by postoperative adjuvant chemotherapy based on the mismatch repair status.

PURPOSE: In Japan, immunohistochemistry for mismatch repair (MMR) proteins targeted at stage II and III colorectal cancers (CRCs) has been covered by national insurance since October, 2022. This study aimed to clarify the long-term outcomes of patients with stage II and III CRCs receiving postoperative adjuvant chemotherapy based on their MMR status. METHODS: The outcomes of 640 patients who underwent radical surgery for stage II and III CRCs were analyzed retrospectively. RESULTS: Deficient MMR (dMMR) was diagnosed in 41 (13.3%) patients with stage II and 28 (9.1%) patients with stage III CRC. The overall survival and recurrence rates were not significantly different between the patients with stage II and those with stage III CRC. The risk factors for recurrence among those with stage II CRC were tumors on the left side, T4 disease, and the presence of BRAF wild type. The recurrence rates were lower in the stage II CRC patients with sporadic dMMR than in those with suspected Lynch syndrome (LS). The first site of recurrence was more frequently the peritoneum or distant lymph node in patients with dMMR. CONCLUSIONS: Stage II CRC patients with sporadic dMMR were found to have a very good prognosis. On the other hand, peritoneal dissemination or distant lymph node metastasis tended to develop in patients with dMMR.

Colorectal Cancer with BRAF V600E Mutation: Trends in Immune Checkpoint Inhibitor Treatment.

Colorectal cancer (CRC) with BRAF V600E mutation presents a formidable scientific and clinical challenge due to its aggressive nature and poor response to standard therapeutic approaches. BRAF V600E mutation-induced conspicuous activation of the MAPK pathway contributes to the relentless tumor progression. Nevertheless, the efficacy of multi-targeted MAPK pathway inhibition remains suboptimal in clinical practice. Patients with high microsatellite instability (MSI-H) have shown favorable results with immune checkpoint inhibitors (ICIs). The combination of the MAPK pathway inhibition with ICIs has recently emerged as a promising regimen to improve clinical outcomes in the microsatellite stable (MSS) subgroup of BRAF V600E-mutant metastatic CRC patients. In this review, we elucidate the unique tumor biology of BRAF V600E-mutant CRC, with a particular focus on the immune features underlying the rationale for ICI treatments in the MSI-H and MSS subpopulations, then highlight the trends in clinical trials of the ICI therapy for BRAF V600E-mutant metastatic CRC.

The Expression and Clinicopathological Significance of BRAF V600E and Mucin 6 in Intrahepatic Cholangiocarcinoma: A Retrospective Study.

Aim. The study aims to explore the expression levels and clinicopathological significance of BRAF V600E and mucin 6 in intrahepatic cholangiocarcinoma. Method. Immunohistochemistry for BRAF V600E and mucin 6 was performed in 110 patients with intrahepatic cholangiocarcinoma. Subsequently, a comprehensive review of medical records and clinicopathological analysis was undertaken. Results. BRAF V600E expression was detected in 11 patients (10%); mucin 6 expression was observed in 19 intrahepatic cholangiocarcinoma specimens (17%). Thereafter, Cox regression models indicated that positive expression of either MUC6 positive (hazard ratio = 0.091, 95% confidence interval = 0.034-0.247, P < .001) and BRAF V600E positive (hazard ratio =0.150, 95% confidence interval = 0.058-0.388, P < .001) was significantly linked with longer overall survival for intrahepatic cholangiocarcinoma patients. Conclusion. The study concludes that positive expression of BRAF V600E and mucin 6 could potentially implied significant survival benefits for patients diagnosed with intrahepatic cholangiocarcinoma.

Efficacy and safety of the combination of encorafenib/cetuximab with or without binimetinib in patients with BRAF V600E-mutated metastatic colorectal cancer: an AGEO real-world multicenter study.

BACKGROUND: The combination of encorafenib with cetuximab has become the standard of care in patients with BRAF V600E-mutated metastatic colorectal cancer (mCRC) after a prior systemic therapy. This study aims to describe the efficacy and safety of encorafenib/cetuximab +/- binimetinib in patients with BRAF V600E-mutated mCRC in a real-world setting. PATIENTS AND METHODS: This retrospective study included patients with BRAF V600E-mutated mCRC who received this combination from January 2020 to June 2022 in 30 centers. RESULTS: A total of 201 patients were included, with 55% of women, a median age of 62 years, and an Eastern Cooperative Oncology Group performance status (ECOG-PS) >1 in 20% of cases. The main tumor characteristics were 60% of right-sided primary tumor, 11% of microsatellite instability/mismatch repair deficient phenotype, and liver and peritoneum being the two main metastatic sites (57% and 51%). Encorafenib/cetuximab +/- binimetinib was prescribed in the first, second, third, and beyond third line in 4%, 56%, 29%, and 11%, respectively, of cases, with the encorafenib/cetuximab/binimetinib combination for 21 patients (10%). With encorafenib/cetuximab treatment, 21% of patients experienced grade ≥3 adverse events (AEs), with each type of grade ≥3 AE observed in <5% of patients. The objective response rate was 32.2% and the disease control rate (DCR) was 71.2%. The median progression-free survival (PFS) was 4.5 months [95% confidence interval (CI) 3.9-5.4 months] and the median overall survival (OS) was 9.2 months (95% CI 7.8-10.8 months). In multivariable analysis, factors associated with a shorter PFS were synchronous metastases [hazard ratio (HR) 1.66, P = 0.04] and ECOG-PS >1 (HR 1.88, P = 0.007), and those associated with a shorter OS were the same factors (HR 1.71, P = 0.03 and HR 2.36, P < 0.001, respectively) in addition to treatment beyond the second line (HR 1.74, P = 0.003) and high carcinoembryonic antigen level (HR 1.72, P = 0.003). CONCLUSION: This real-world study showed that in patients with BRAF V600E-mutated mCRC treated with encorafenib/cetuximab +/- binimetinib, efficacy and safety data confirm those reported in the BEACON registration trial. The main poor prognostic factors for this treatment are synchronous metastases and ECOG-PS >1.

Osimertinib-induced BRAF mutation in a single metastatic lesion among multiple pulmonary lesions in a case of lung cancer with EGFR exon 19 deletion.

One of the resistant mechanisms of EGFR-TKIs is BRAF V600E mutation. Herein, we present the case of a 54-year-old Japanese female who underwent a right middle lobectomy for pathological stage IIB lung adenocarcinoma. One year and nine months after the surgery, she developed multiple intrapulmonary metastases. Osimertinib was administered due to EGFR exon 19 deletion. Although all intrapulmonary metastases had shrunk, the nodule at the superior segment of left lung enlarged after postoperative 4 years. The tumour was resected and BRAF V600E mutation and exon 19 deletion were detected. Three months after treatment with dabrafenib and trametinib instead of osimertinib, the remaining intrapulmonary metastases increased again. The continued growth of the metastatic foci even after EGFR-TKI may indicate an acquired resistance. Thus, a repeat biopsy will aid in confirming the new gene expression. It should have been necessary to administer an additional dose of dabrafenib and trametinib without discontinuing osimertinib.

Intraglandular dissemination: a special pathological feature.

Intraglandular dissemination is an important pathological feature of thyroid cancer, yet the biological characteristics of this phenomenon remain relatively underexplored. This paper aims to provide a comprehensive overview of its biological behaviors, protein expressions, and identification methods. Several retrospective studies have found that thyroid cancers with intraglandular dissemination have higher rates of lymph node metastasis, capsule invasion, and vascular invasion, exhibiting more aggressive biological behavior. Immunohistochemistry results show abnormal expression of proteins such as FKBP5, CENPF, CX26, KIF11, PTK7, which are associated with poor prognosis in thyroid cancers with intraglandular dissemination, offering potential guidance for specific targeted therapy in the future. Moreover, adjunctive techniques including ultrasound, fine-needle aspiration, and genetic testing offer valuable support in accurately identifying these cases, facilitating moreproactive treatment and closer follow-up.

Role of mitochondria and potential of mitochondria-targeted therapy in BRAF mutant cancer: A review.

The classical mitogen-activated protein kinase (MAPK) signaling pathway, the Ras/Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK protein kinase cascade, is a conserved cascade that regulates cell growth, differentiation, and proliferation. The significance of BRAF in cancer was established with the discovery of cancer-activating mutations in BRAF in several human tumors in 2002. Currently, BRAF is recognized as a driver mutation that affects cancer phenotypes in different ways, making it an important therapeutic target for cancer. BRAF-selective inhibitors have shown promise in clinical trials involving patients with metastatic melanoma. However, resistance mechanisms to BRAF inhibitors therapy have resulted in short-lived therapeutic responses. Further in-depth research is imperative to explore resistance mechanisms that oppose the effectiveness of BRAF inhibitors. Metabolic reprogramming has emerging role in BRAF-mutant cancers. In particular, mitochondrial metabolism and its closely related signaling pathways mediated by mitochondria have become recognized as potential new targets for treating BRAF-mutant cancers. This review, examines the progress in understanding BRAF mutations in cancer, the clinicopathological correlation of BRAF inhibitors, and recent advances in mitochondrial metabolism, mitochondrial dynamics and mitochondrial mediated death in BRAF-mutant cancer. This review will inform future cancer research and lay the foundation for novel treatment combinations of BRAF-mutant cancers.

Canadian Consensus for Treatment of BRAF V600E Mutated Pediatric and AYA Gliomas.

Background: The treatment of BRAF V600E gliomas with BRAF inhibitors (BRAFis) and MEK inhibitors (MEKis) has been increasingly integrated into clinical practice for pediatric low-grade gliomas (PLGGs) and pediatric high-grade gliomas (HGGs). However, some questions remain unanswered, such as the best time to start targeted therapy, duration of treatment, and discontinuation of therapy. Given that no clinical trial has been able to address these critical questions, we developed a Canadian Consensus statement for the treatment of BRAF V600E mutated pediatric as well as adolescent and young adult (AYA) gliomas. Methods: Canadian neuro-oncologists were invited to participate in the development of this consensus. The consensus was discussed during monthly web-based national meetings, and the algorithms were revised until a consensus was achieved. Results: A total of 26 participants were involved in the development of the algorithms. Two treatment algorithms are proposed, one for the initiation of treatment and one for the discontinuation of treatment. We suggest that most patients with BRAF V600E gliomas should be treated with BRAFis ± MEKis upfront. Discontinuation of treatment can be considered in certain circumstances, and we suggest a slow wean. Conclusions: Based on expert consensus in Canada, we developed algorithms for treatment initiation of children and AYA with BRAF V600E gliomas as well as a discontinuation algorithm.

Rapid but nondurable response of a BRAF exon 15 double-mutated spindle cell sarcoma to a combination of BRAF and MEK inhibitors.

INTRODUCTION: BRAF V600E substitution predicts sensitivity of a cancer to BRAF inhibitor therapy. The mutation is rarely found in soft-tissue sarcomas. Here we describe a case of undifferentiated spindle cell sarcoma showing primary insensitivity to standard chemotherapy and pronounced but non-sustained response to BRAF/MEK inhibitors at recurrence. CASE PRESENTATION: A 13-year-old girl was diagnosed with low-grade spindle cell sarcoma of pelvic localization, BRAF exon 15 double-mutated: c.1799T>A p.V600E and c.1819T>A p.S607T in cis-position. The tumor showed resistance to CWS-based first-line chemotherapy and was treated surgically by radical resection. Seven months after surgery the patient developed metastatic relapse with abdominal carcinomatosis. Combined targeted therapy with BRAF/MEK inhibitors afforded complete response in 1 month and was continued, though complicated by severe side effects (fever, rash) necessitating 1-2 week toxicity breaks. After 4 months from commencement the disease recurred and anti-BRAF/MEK regimen consolidation was unsuccessful. Intensive salvation chemotherapy was ineffective. Empirical immunotherapy afforded a transient partial response giving way to fatal progression with massive, abdominal cocoon-complicated peritoneal carcinomatosis. CONCLUSION: This is the first report of spindle cell sarcoma BRAF V600E/S607T double-mutated, responding to a combination of B-Raf and MEK inhibitors. Despite the low histological grade and radical surgical treatment of the tumor at primary manifestation, the disease had aggressive clinical course and the response to BRAF/MEK targeted therapy at recurrence was complete but nondurable. Empirical use of pembrolizumab provided no unambiguous evidence on the clinical relevance of immunotherapy in protein kinase -rearranged spindle cell tumors.

Neoadjuvant BRAF and MEK inhibitor therapy elicits pathological complete response in stage IIIA non-small cell lung cancer harboring BRAF V600E mutation: A case report.

In recent years, significant improvement has been made in the management of non-small cell lung cancer (NSCLC), primarily driven by advances in targeted therapy and immunotherapy. Research on neoadjuvant targeted therapy has also experienced considerable development, primarily directed towards NSCLC harboring epidermal growth factor receptor or anaplastic lymphoma kinase mutations. Nevertheless, there remains a dearth of studies investigating neoadjuvant targeted therapy in the context of BRAF (V-Raf murine sarcoma viral oncogene homolog B) V600E mutant NSCLC. Herein, we describe the clinical trajectory of a stage IIIA NSCLC patient who underwent a two-month course of neoadjuvant targeted therapy comprising BRAF and MEK (mitogen-activated extracellular signal-regulated kinase) inhibitors prior to surgical intervention, and subsequent postoperative evaluation unveiled a pathological complete response. The case reported here indicates the efficacy and safety of combining BRAF and MEK inhibitors as neoadjuvant targeted therapy in BRAF V600E-mutant NSCLC and suggests the potential viability of such a therapeutic modality in improving treatment outcomes in this subset of NSCLC.

Treatment of Unresectable BRAF V600E, TERT-Mutated Differentiated Papillary Thyroid Cancer With Dabrafenib and Trametinib.

Complete surgical resection of differentiated papillary thyroid cancer (PTC) is associated with an excellent prognosis. However, for locally invasive PTC, disease-specific morbidity and mortality increases when microscopic margin negative resection (R0) or complete macroscopic resection (R1) is not feasible. Neoadjuvant dabrafenib and trametinib (DT) used in BRAF V600E-positive, unresectable anaplastic thyroid cancer has allowed for R0 or R1 resection and improved survival rates. We demonstrate feasibility of using neoadjuvant DT in a patient with BRAF V600E and TERT-mutated PTC for whom R0/R1 resection was initially aborted due to predicted unacceptable morbidity. The patient was treated with neoadjuvant DT for 5 months, at which time disease was undetectable on imaging with near resolution on final pathology; however, subsequent rapid recurrence after discontinuation of neoadjuvant DT occurred. Neoadjuvant DT offers promise in future cohorts of patients with locally invasive BRAF V600E and TERT-mutated PTC for whom neoadjuvant therapy can reduce surgical morbidity while still allowing for R0/R1 resection.

Long-term response to MEK inhibitor monotherapy in a patient with papillary thyroid carcinoma harboring BRAF V600E mutation.

Solid tumors harboring mutations in the Braf gene (BRAF) are currently treated by combination Braf/MEK inhibitor therapy, and there is an extensive literature on patient response rates. Alternatively, few studies have documented the clinical response of BRAF mutation-positive solid tumors to MEK inhibitor monotherapy. We report the case of a 57-year-old female diagnosed with papillary thyroid carcinoma and progressive lung metastases initially treated by total thyroidectomy and subsequent thyroid-stimulating hormone suppression therapy. Next-generation sequencing revealed that the tumor harbored a BRAF V600E mutation, and the patient was enrolled in a clinical study of the oral MEK1/2 inhibitor binimetinib. Shortly after starting treatment, the patient experienced pneumothorax due to rapid regression of lung metastases, and computed tomography after 6 months of binimetinib treatment revealed a partial sustained response. One year later, the dose was reduced because of an acneiform rash. After 5 years of binimetinib treatment, lung metastases had regrown, and treatment was switched to the oral multikinase inhibitor lenvatinib. This case demonstrates the potential of MEK inhibitor monotherapy as an alternative treatment for BRAF mutation-positive papillary thyroid carcinoma.

Eosinophilic Cells in Ovarian Borderline Serous Tumors as a Predictor of BRAF Mutation.

According to recent reports, ovarian serous borderline tumor (SBT) harboring the BRAF V600E mutation is associated with a lower risk of progression to low-grade serous carcinoma. Preliminary observations suggest that there may be an association between eosinophilic cells (ECs) and the above-mentioned mutation, so this study aimed to evaluate interobserver reproducibility for assessing ECs. Forty-two samples of SBTs were analyzed for ECs with abundant eosinophilic cytoplasm. Immunohistochemical staining and genetic pro-filing were performed in all cases to verify the BRAF V600E mutation. A BRAF V600E mutation was found in 19 of 42 (45%) cases. Inter-observer reproducibility in the assessment of ECs was substantial (κ = 0.7). The sensitivity and specificity for predicting the mutation were 79% and 91%, respectively. Patients with BRAF-mutated SBTs were significantly younger than those without mutation (p = 0.005). SBTs with BRAF mutation were less likely to be accompanied by non-invasive implants than wild-type SBT: 12% (2/17) versus 33% (6/18). Seven cases were excluded due to incomplete cytoreductive surgery. Nevertheless, Fisher's exact test showed no significant differences between the two groups (p = 0.228). Overall, this study strengthens the idea that ECs in ovarian SBTs may represent a mutation with prognostic significance, which can serve as a primary screening test for BRAF V600E mutation in this pathologic entity.

Analysis of Immunohistochemical Expression of BRAF (V600E) Mutation in Serrated Colorectal Polyps: A Study from Tertiary Hospital in Oman.

BACKGROUND AND AIM: Colorectal cancer (CRC) is considered one of the most common cancers in the world. Serrated polyps were found to be precursor lesions for CRC. BRAF mutation (V600E) has been strongly linked to the development of these lesions. No previous study concerning BRAF immunohistochemical expression in serrated polyps- was done in Oman. The primary objective of our study was to assess the prevalence of BRAF (V600E) mutation in serrated colorectal polyps in the Omani population. The secondary objectives were to assess the prevalence of serrated polyps and their characteristic features: type, site and size as well as the relationship between BRAF (V600E) mutation and polyp type, site and size. MATERIALS AND METHODS: Ninety-one hyperplastic polyps (HP) (76.5%), 24 sessile serrated lesions (SSL) (20.2%) and 4 cases of tubular adenomas with low grade dysplasia (3.4%) were studied for BRAF (V600E) immunohistochemical expression. No case of traditional serrated adenoma (TSA) was present. Control cases of craniopharyngioma and papillary thyroid carcinoma were included. RESULTS: BRAF (V600E) IHC was positive in 63 of the HP polyps (69.2%), 13 SSLs (54.2%) and none of the adenomatous polyps. The majority of positive polyps (75.0%) were ≤5 mm in size, 17.9% were 5-10 mm and 7.1% were ≥10 mm in size.  The majority of BRAF (V600E) positive polyps (68.1 %) were in the distal colon and 31.9 % were in the proximal colon. The majority of positive cases for BRAF (V600E) were showing multiple polyps (61.8 %). None of the tubular adenomas showed any BRAF (V600E) positivity. CONCLUSION: Serrated polyps are now well known for their potential to develop CRC. Immunohistochemistry is an easy and reproducible way to detect BRAF (V600E) mutation. Our study showed there is high prevalence (64.3%) of BRAF mutation in serrated polyps in the Omani population. The majority of these polyps- were HP and SSL; and ≤5 mm in size and located in the distal colon.

BRAF-V600E mutations in plasma and peripheral blood mononuclear cells correlate with prognosis of pediatric Langerhans cell histiocytosis treated with first-line therapy.

BACKGROUND: The clinical relevance of BRAF-V600E alleles in peripheral blood mononuclear cells (PBMCs) and the prognostic impact of the mutants in cell-free (cf) and PBMC DNAs of Langerhans cell histiocytosis (LCH) have not been fully clarified in pediatric LCH. METHODS: We retrospectively determined the levels of BRAF-V600E mutation in paired plasma and PBMC samples at the time of diagnosis of LCH. Subsequently, we performed a separate or combined analysis of the clinical and prognostic impact of the mutants. RESULTS: We assessed BRAF-V600E mutation in peripheral blood from 94 patients of childhood LCH. Our data showed that cfBRAF-V600E was related to young age, multiple-system (MS) disease, involvements of organs with high risk, increased risk of relapse, and worse progression-free survival (PFS) of patients. We also observed that the presence of BRAF-V600E in PBMCs at baseline was significantly associated with MS LCH with risk organ involvement, younger age, and disease progression or relapse. The coexisting of plasma(+)/PBMC(+) identified 36.2% of the patients with the worst outcome, and the hazard ratio was more significant than either of the two alone or neither, indicating that combined analysis of the mutation in plasma and PBMCs was more accurate to predict relapse than evaluation of either one. CONCLUSIONS: Concurrent assessment of BRAF-V600E mutation in plasma and PBMCs significantly impacted the prognosis of children with LCH. Further prospective studies with larger cohorts need to validate the results of this study.

BRAF V600E-mutant colorectal cancer with CNS metastases treated successfully with encorafenib, binimetinib and cetuximab.

This report describes a case of BRAF V600E-mutated colorectal cancer with CNS metastases in which treatment with encorafenib, binimetinib and cetuximab was effective. There is limited information on the ability of encorafenib, binimetinib and cetuximab to enter the CNS.The patient was a 53-year-old man was diagnosed with ascending colon cancer (cT3N3M1c stage IVc). BRAF V600E mutation was confirmed. FOLFOX was started, but CNS metastases soon appeared. Encorafenib, binimetinib and cetuximab were administered and had a favorable effect on the CNS lesions. The patient initially responded well, but his disease progressed 2 months later. Further research is needed to improve management strategies for BRAF V600E-mutated colorectal cancer with CNS metastases.

[Box: see text].

BRAF V600E-induced distinct DNA damage response defines the therapeutic potential of p53 activation for TP53 wild-type colorectal cancer.

BRAF V600E, one of the most frequent mutations in the MAPK pathway, confers poor prognosis to colorectal cancers (CRCs), partly because of chemotherapeutic resistance. Oncogene-induced DNA damage responses (DDRs) that primarily activate p53 are important mechanistic barriers to the malignant transformation of cells; however, the mechanism underlying this impairment in cancer remains unknown. Here, we evaluated the responses of BRAFV600E-induced DDRs in two CRC cell lines, SW48 and LIM1215, both of which harbor wild-type TP53, KRAS, and BRAF. BRAFV600E transduction exhibited distinct phenotypes in these cells: SW48 cell proliferation markedly decreased, whereas that of LIM1215 increased. BRAFV600E expression induced the activation of oncogene-induced DDR signaling in SW48 cells, but not in LIM1215 cells, whereas chemotherapeutic agents similarly activated DDRs in both cell lines. Knockdown experiments revealed that these responses in SW48 cells were mediated by p53-p21 pathway activation. Comet assay (both alkaline and neutral) revealed that BRAFV600E increased single-strand breaks to the same extent in both cell lines; however, in case of LIM1215 cells, it only facilitated double-strand breaks. Furthermore, the proliferation of LIM1215 cells, wherein no oncogene-induced DDRs occurred, was synergistically inhibited upon MDM2 inhibitor-mediated p53 activation combined with MEK inhibition. Taken together, these distinct DDR signaling responses highlight the novel characteristics of BRAFV600E-mutated CRC cells and define the therapeutic potential of p53 activation combined with MAPK inhibition against TP53 wild-type CRC harboring a BRAFV600E mutation.

Hairy cell leukemia - etiopathogenesis, diagnosis and modern therapeutic approach.

Hairy cell leukemia (HCL) represents 2% of all leukemia cases, with men aged above 55 years being the most affected. The most common symptoms of this type of leukemia include splenomegaly, monocytopenia, and neutropenia. In the basic blood count examination, leukopenia with monocytopenia and granulocytopenia, as well as aplastic anemia and/or thrombocytopenia occur. The mutation of ß-rapidly accelerated fibrosarcoma (BRAF) proto-oncogene, which can be found in nearly 100% of patients, is an important feature of HCL. Immunophenotypic analysis of the HCL cells reveals high expression of B-lineage antigens, including CD19, CD20, and CD22. Additionally, CD11c, CD25, CD103, and CD123 belong to specific markers of HCL. Lactate dehydrogenase activity and ß-2-microglobulin concentration are also important in the patient's assessment. The differential diagnosis between HCL, hairy cell leukemia variant (HCL-V) and splenic marginal zone lymphoma (SMZL) is of first importance. Currently, the main treatment for HCL involves the use of purine analogues, excluding pregnant women, individuals with severe infections, and those with relapsing HCL.