Down-Regulation of CD25 Antigen in Hairy Cell Leukemia Patients after Treatment

Abstract Background: Hairy Cell Leukemia (HCL) is a rare hematological malignancy, comprising only of 2% of all leukemias, with an estimated 900 new cases diagnosed each year in the United States. HCL displays a characteristic immunophenotypic profile that include pan-B cell markers including CD103, CD11c, and CD25. World Health Organization guidelines defines two forms of HCL, classic HCL (cHCL) and variant HCL (HCLv) as two distinct clinical entities. Patients with cHCL have a distinct immunophenotypic profile on their malignant leukemic cells including CD20+, CD19+, CD11c+, CD25+, CD103+, and CD123+, while the leukemic cells from patients with HCLv show CD11c+, CD20+ and CD19+, while lacking CD25 and CD123 expression. Some patients with cHCL will retain CD25 positivity while demonstrating negativity for other typical markers, herein termed atypical HCL (aHCL). Presence or absence of CD25 is an important determinant in classifying patients into cHCL and HCLv. Although it has previously been reported that CD25 expression may be lost during treatment with the targeted agent vemurafenib, we sought to identify whether this immunophenotypic change occurs following other treatment types, including standard purine nucleoside analog therapy and with targeted BTK inhibition. Methods: Adult patients (≥18 years) with a diagnosis of HCL whom had immunophenotype data collected before and after treatment between 2010 and 2018 were included in the study. Immunophenotype and morphological characteristics of initial and follow-up peripheral blood, bone marrow aspirate, and core biopsy specimens were reviewed and correlated with the treatment received. Results: We evaluated 30 HCL patients who underwent different therapies. All available specimens were reviewed and showed morphologic features characteristic for cHCL (n=26, 86.7%), and aHCL (n=4, 13.3%). The median age at HCL diagnosis was 50 years (44-76 years) with male predominance (76%). Patients with aHCL were treated with ibrutinib (n=2) and pentostatin (n=2). Patients with cHCL were treated with pentostatin (n=12), ibrutinib (n=8), vemurafenib (n=4), dabrafenib (n=1), and cladribine (n=1). Bone marrow analyses showed that all the patients had leukemic B-lymphocyte co-expression of CD19, CD20, CD103, CD11c, CD25, and CD123 prior to treatment. Some patients also had a smaller percentage of lymphocytes lacking CD25 expression along with the CD25 positive lymphocytes. Follow-up bone marrow and peripheral blood analysis showed that almost half (n=14, 46%) of treated patients had a partial or complete loss of CD25 expression regardless of the treatment type. Leukemic cells continued to express other HCL signature markers. Conclusion: Our study indicates that during the course of disease some patients display a loss of CD25 expression after therapy. This phenomenon was observed across different therapies and is not specific to the type of treatment. This is the first study to show treatment-dependent CD25 variability with pentostatin, ibrutinib and dabrafenib. Our results advocate for caution when using CD25 for the differential diagnosis of cHCL versus HCLv in treated patients. Future studies are needed in larger patient cohorts to determine the overall role and utility of CD25 in the diagnosis of cHCL and HCLv. Disclosures Lozanski: Genentech: Research Funding; Stem Line: Research Funding; BI: Research Funding; Novartis: Research Funding; Beckman: Research Funding; Coulter: Research Funding. Andritsos:Astra Zeneca: Consultancy; HCLF: Membership on an entity's Board of Directors or advisory committees.

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Peripheral blood and bone marrow changes following 2′-deoxycoformycin therapy in hairy cell leukemia. Results of 200 weeks' follow-up

Cancer ◽

10.1002/1097-0142(19890101)63:1<14::aid-cncr2820630103>3.0.co;2-i ◽

1989 ◽

Vol 63 (1) ◽

pp. 14-22 ◽

Cited By ~ 11

Author(s):

Bakul I. Dalal ◽

Lydia Freier ◽

James B. Johnston ◽

Colin C. Merry ◽

Lyonel G. Israels

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Hairy Cell Leukemia ◽

Hairy Cell ◽

Cell Leukemia

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Treatment of hairy cell leukemia with alternating cycles of pentostatin and recombinant leukocyte A interferon: results of a phase II study.

Journal of Clinical Oncology ◽

10.1200/jco.1990.8.4.721 ◽

1990 ◽

Vol 8 (4) ◽

pp. 721-730 ◽

Cited By ~ 22

Author(s):

A Martin ◽

S Nerenstone ◽

W J Urba ◽

D L Longo ◽

J B Lawrence ◽

...

Keyword(s):

Bone Marrow ◽

Hairy Cell Leukemia ◽

Pathologic Complete Response ◽

Hairy Cell ◽

Cell Leukemia ◽

Cell Infiltrate ◽

Recombinant Interferon ◽

Bone Marrow Biopsies ◽

Hairy Cells

Fifteen patients with hairy cell leukemia (HCL) were treated with deoxycoformycin (pentostatin; dCF) (4 mg/m2 intravenous [IV] every week x 3) and recombinant interferon-alpha 2a (rIFN-alpha 2a) (3 x 10(6) units subcutaneously [SC] daily x 4 weeks) in alternating months for a total of 14 months. Eleven patients had undergone splenectomy; four had received prior systemic therapy with chlorambucil and/or steroids. All 15 are evaluable for toxicity and peripheral blood response, while 14 are assessable for bone marrow response. Toxicity was tolerable with grade 3 or 4 nausea and vomiting in three patients, neutropenic fevers in five, transient but significant depression in eight, and localized cutaneous herpes zoster in four. Circulating hairy cells were undetectable by the end of the first month in 10 of 13 patients, and by the end of the second month in the other three. Fourteen patients had bilateral bone marrow biopsies performed at baseline after 6 months of treatment, at the end of treatment (14 months), and at 6-month intervals during follow-up. Before treatment, all patients had hypercellular marrows with hairy cels replacing normal marrow elements; all showed at least a 95% clearing of their hairy cell infiltrate by 6 months of therapy. However, small collections of residual hairy cells could be detected intermittently on at least one side of bilateral samples in all patients. All patients have completed treatment with a median duration of follow-up off therapy of 27 months (range, 15 to 31 months). To date, all peripheral counts and serum soluble interleukin-2 receptor (sIL2R) levels remain stable, and no patient has had progression of the hairy cell infiltrate in the bone marrow. Although no patient achieved a pathologic complete response, alternating monthly cycles of dCF and rIFN-alpha 2a produced durable partial remissions (PRs) in all patients. Continued follow-up is required to determine the length of such remissions.

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Minimal residual disease may predict bone marrow relapse in patients with hairy cell leukemia treated with 2-chlorodeoxyadenosine

Blood ◽

10.1182/blood.v87.4.1556.bloodjournal8741556 ◽

1996 ◽

Vol 87 (4) ◽

pp. 1556-1560 ◽

Cited By ~ 65

Author(s):

S Wheaton ◽

MS Tallman ◽

D Hakimian ◽

L Peterson

Keyword(s):

Bone Marrow ◽

Minimal Residual Disease ◽

Hairy Cell Leukemia ◽

Residual Disease ◽

Hairy Cell ◽

Cell Leukemia ◽

Hematoxylin And Eosin ◽

Anti Cd20 ◽

Minimal Residual

Minimal residual disease (MRD) can be detected in bone marrow core biopsies of patients with hairy cell leukemia (HCL) after treatment with 2-chlorodeoxyadenosine (2-CdA) using immunohistochemical (IHC) techniques. The purpose of this study was to determine whether the presence of MRD predicts bone marrow relapse. We studied paraffin- embedded bone marrow core biopsies from 39 patients with HCL in complete remission (CR) 3 months after a single cycle of 2-CdA. Biopsies performed 3 months posttherapy and annually thereafter were examined by routine hematoxylin and eosin (H&E) staining and IHC using the monoclonal antibodies (MoAbs) anti-CD45RO, anti-CD20, and DBA.44. At 3 months after therapy, 5 of 39 (13%) patients had MRD detectable by IHC that was not evident by routine H&E staining. Two of the five patients (40%) with MRD at 3 months have relapsed, whereas only 2 of 27 (7%) patients with no MRD and at least 1 year of follow up relapsed (P = .11). Over the 3-year follow-up period, two additional patients developed MRD. Overall, three of six (50%) patients with MRD detected at any time after therapy have relapsed, whereas only 1 of 25 (4%) patients without MRD has relapsed (P = .016). These data suggest that the presence of MRD after treatment with 2-CdA may predict relapse.

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Response to 2'-deoxycoformycin after failure of interferon-alpha in nonsplenectomized patients with hairy cell leukemia

Blood ◽

10.1182/blood.v68.1.297.bloodjournal681297 ◽

1986 ◽

Vol 68 (1) ◽

pp. 297-300

Author(s):

KA Foon ◽

GM Nakano ◽

CA Koller ◽

DL Longo ◽

RG Steis

Keyword(s):

Bone Marrow ◽

Peripheral Blood ◽

Hairy Cell Leukemia ◽

Subsequent Treatment ◽

Spleen Size ◽

Hairy Cell ◽

Cell Leukemia ◽

Massive Splenomegaly ◽

Ifn Alpha ◽

Severe Pancytopenia

Two patients with hairy cell leukemia with massive splenomegaly and severe pancytopenia were treated with recombinant alpha-A interferon (IFN-alpha-2a). There was no significant response to a trial of IFN- alpha-2a (11 and 20 weeks) with respect to blood counts or spleen size. Subsequent treatment with 2′-deoxycoformycin (dCF) for 8 consecutive weeks (4 mg/m2/wk) resulted in normalization of spleen size and a normalization of peripheral blood counts and bone marrow in one patient. The second patient demonstrated a reduction in spleen size and improved blood counts following 9 weeks of dCF therapy but eventually became refractory. This demonstrates that dCF is non-cross-resistant with interferon and confirms the efficacy of dCF in nonsplenectomized patients.

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Hairy Cell Leukemia Variant Developing in a Background of Polycythemia Vera

Archives of Pathology & Laboratory Medicine ◽

10.5858/2003-127-e209-hclvdi ◽

2003 ◽

Vol 127 (4) ◽

pp. e209-e211

Author(s):

Nadine P. Kelly ◽

Serhan Alkan ◽

Sucha Nand

Keyword(s):

Polycythemia Vera ◽

Hairy Cell Leukemia ◽

Flow Cytometric Analysis ◽

Leukemic Cells ◽

Hairy Cell ◽

Cell Leukemia ◽

Cd25 Expression ◽

Flow Cytometric ◽

Erythroid Hyperplasia ◽

Prominent Nucleolus

Abstract We report a case of hairy cell leukemia variant developing in a background of polycythemia vera in a 77-year-old man who presented with lymphocytosis and splenomegaly. Classic hairy cell leukemia in a patient with polycythemia vera has been reported previously, but hairy cell leukemia variant arising in a patient with polycythemia vera has never been described to the best of our knowledge. Initial testing of the peripheral blood showed circulating medium to large leukemic cells with large, centrally placed nuclei, each containing a prominent nucleolus, and some cells showed cytoplasmic projections. A bone marrow biopsy had marked myeloid and erythroid hyperplasia and interstitially distributed cells with a fried-egg appearance. We verified a monoclonal B-cell population by flow cytometric analysis, which revealed expression of bright CD11c, CD22, and CD103 expression, and a lack of CD25 expression. The patient received a 5-day course of cladribine and subsequently had a complete remission. Approximately 2 months later, he had a relapse and was treated with pentostatin; however, he had no clinical response and died.

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Hairy Cell Leukemia Variant With Features of Intrasinusoidal Bone Marrow Involvement

Archives of Pathology & Laboratory Medicine ◽

10.5858/2005-129-395-hclvwf ◽

2005 ◽

Vol 129 (3) ◽

pp. 395-398

Author(s):

Charin Ya-In ◽

Joseph Brandwein ◽

Dominic Pantalony ◽

Hong Chang

Keyword(s):

Bone Marrow ◽

Hairy Cell Leukemia ◽

Bone Marrow Involvement ◽

Lymphoid Cells ◽

World Health ◽

White Pulp ◽

Tartrate Resistant Acid Phosphatase ◽

Hairy Cell ◽

Cell Leukemia ◽

Diffuse Infiltration

Abstract Hairy cell leukemia variant (HCL-V) is a rare lymphoproliferative disorder. We report a case of HCL-V with an intrasinusoidal pattern of bone marrow involvement without interstitial or diffuse infiltration that is typical of HCL and its variant. The peripheral blood and bone marrow aspirates demonstrated abnormal lymphoid cells with cytoplasmic projections that were weakly positive for tartrate-resistant acid phosphatase cytochemical staining. Immunostaining of the bone marrow biopsy specimen showed that these cells were strongly positive for CD20, located within bone marrow sinusoids, and weakly positive for DBA44. By flow cytometry, these cells were positive for CD19, CD20, CD11c, and CD103, exhibited λ light chain restriction, and were negative for CD25. The patient was initially diagnosed as having splenic lymphoma with villous lymphocytes (SLVL) or splenic marginal zone lymphoma (SMZL) (World Health Organization designation) and treated with fludarabine followed by splenectomy with simultaneous liver biopsy. The pathologic analysis of the spleen revealed infiltration of red pulp by the critical cells without white pulp involvement, which is characteristic of HCL and HCL-V but not of SLVL (SMZL). This case illustrates an atypical marrow presentation of HCL-V and emphasizes the need to correlate all clinical and pathologic data, including tissue biopsy, in reaching a diagnosis.

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Bendamustine and Rituximab for the Treatment of Multiply Relapsed Hairy Cell Leukemia,

Blood ◽

10.1182/blood.v118.21.3909.3909 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3909-3909

Author(s):

Robert J. Kreitman ◽

Maryalice Stetler-Stevenson ◽

Wyndham H. Wilson ◽

Sapolsky Jeffrey ◽

Laura Roth ◽

...

Keyword(s):

B Cell ◽

Dose Level ◽

Hairy Cell Leukemia ◽

Research Funding ◽

Hairy Cell ◽

Cell Leukemia ◽

Purine Analog ◽

Prospective Phase ◽

Dose Levels

Abstract Abstract 3909 Background: Hairy cell leukemia (HCL) is highly sensitive to purine analogs cladribine (CdA) and pentostatin (DCF), but patients who relapse have decreasing remission rates with each course and can eventually become purine analog-refractory. Bendamustine and rituximab (BR) have been reported as effective with acceptable toxicity in several B-cell malignancies, particularly B-cell lymphomas and chronic lymphocytic leukemia. The structure of bendamustine contains an alkylating group and also part of cladribine, suggesting it might be useful in HCL. In one case report, bendamustine achieved a transient partial response in a patient with relapsed/refractory HCL, but its activity in other patients with this disease is not reported. The combination of DCF and rituximab (DCFR) is reported to achieve high complete remission (CR) rates in HCL in retrospective series, but prospective phase II trials of this combination have not been reported. Methods: To determine the activity of BR relative to DCFR in HCL, a randomized trial was undertaken in multiply relapsed HCL comparing the 2 regimens in which each arm could constitute a prospective phase II trial, with 2-way crossover for lack of response to or relapse from the originally assigned regimen. The primary endpoint is an overall response rate of 65% for each arm and the 2 arms will be compared with respect to response and other secondary endpoints including toxicity, response duration, and eradication of minimal residual disease (MRD). Patients received 6 cycles at 4-week intervals of rituximab 375 mg/m2 days 1 and 15 with either pentostatin at 4 mg/m2 days 1 and 15, or bendamustine days 1 and 2. To test the tolerability of bendamustine prior to randomizing 56 patients between the 2 arms, 12 non-randomized patients received BR using 70 (n=6) or 90 (n=6) mg/m2/dose of bendamustine. Doses of all agents could be delayed but not reduced. Results: A total of 20 patients are so far enrolled and the 12 patients receiving the 2 dose levels of BR are evaluable for response and toxicity. Patients had 1–6 (median 3) prior courses of purine analog and 8 (67%) had prior rituximab. All toxicity was reversible and only 1 patient at 90 mg/m2 required >2-week delay due to prolonged neutropenia and thrombocytopenia. However, this delay was only between cycles 1 and 2 and not between subsequent cycles after responding to BR. Of the 36 cycles of BR administered to each group of 6 patients on the 2 dose levels of bendamustine, 90 vs 70 mg/m2/dose, common grade 3–4 toxicities included lymphopenia (28 vs 22%), leukopenia (19 vs 17%), and thrombocytopenia (14 vs 17%). Febrile neutropenia requiring hospitalization occurred just once in 3 patients at 90 vs 0 patients at 70 mg/m2/dose. Major response was achieved in 10 (83%) of 12 patients. CR was achieved in 3 (50%) of 6 patients at each dose level, while 2 (33%) at 70 and 3 (50%) at 90 mg/m2 achieved clearance of MRD at all sites including bone marrow aspirate by flow cytometry. No patient in CR has relapsed after 8–14 (median 11) months of follow-up. Of 4 patients evaluable by clone-specific real-time PCR, previously reported sensitive to 1 HCL cell in 106 normal, 3 patients at 90 mg/m2/dose were negative. Conclusions: BR can achieve responses including CRs in multiply relapsed HCL, and its safety profile permits comparison of BR with DCFR using the more common dose level of bendamustine, 90 mg/m2 days 1 and 2. Additional patients and follow-up will be required to access durability of response and long-term eradication of MRD, and to compare BR with DCFR (Supported in part by NCI, intramural research program, NIH, Genentech, Inc, and Cephalon, Inc). Disclosures: Kreitman: Cephalon: Research Funding; Genentech: Research Funding. Off Label Use: Use of bendamustine and rituximab for HCL. Arons:Genentech: Research Funding.

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Efficacy and Safety of the BRAF Inhibitor Vemurafenib in Hairy Cell Leukemia Patients Refractory to or Relapsed after Purine Analogs: A Phase-2 Italian Clinical Trial

Blood ◽

10.1182/blood.v124.21.150.150 ◽

2014 ◽

Vol 124 (21) ◽

pp. 150-150 ◽

Cited By ~ 2

Author(s):

Enrico Tiacci ◽

Luca De Carolis ◽

Pier Luigi Zinzani ◽

Alessandro Pulsoni ◽

Francesco Zaja ◽

...

Keyword(s):

Bone Marrow ◽

Hairy Cell Leukemia ◽

Braf Inhibitor ◽

Post Treatment ◽

The Other ◽

Braf V600e ◽

Morphological Evidence ◽

Hairy Cell ◽

Cell Leukemia

Abstract BACKGROUND AND AIMS: Hairy cell leukemia (HCL) is very sensitive to purine analogs (PAs), but ~40% of patients relapse and become progressively less responsive to these myelotoxic and immune-suppressive drugs. Having discovered the BRAF-V600E kinase-activating mutation as the genetic lesion underlying HCL (Tiacci et al, NEJM 2011;364:2305), we performed the first clinical trial of a BRAF inhibitor (vemurafenib) in refractory/relapsed HCL. In particular, this is a phase-2, academic, single-arm, Italian, multi-center (n=8) study (HCL-PG01; EudraCT 2011-005487-13). METHODS: In 11 months we enrolled 28 BRAF-V600E+ HCL patients, needing therapy due to cytopenias and including: i) 6 patients primary refractory to a PA; ii) 21 patients who relapsed early and/or repeatedly after PAs and had received a median of 4 previous therapies; and iii) a 81-year old patient showing severe myelotoxicicity after a PA (discouraging its further use). Previous treatments other than PAs included interferon, rituximab and splenectomy in 12, 14 and 8 patients, respectively. Complete remission (CR) required resolution of cytopenias (N≥1500/mmc, PLT≥100000/mmc, Hb≥11 g/dl), no morphological evidence of HCL cells in the bone marrow biopsy and blood smear, and no splenomegaly. Partial remission (PR) required resolution of cytopenias, and a ≥50% reduction of splenomegaly and of marrow and blood HCL involvement by immunophenotyping. Two patients were not evaluable as they went off-study after ≤1 week of treatment (due to drug-unrelated acute myocardial infarction and consent withdrawal after grade-3 drug-related reversible pancreatitis). RESULTS: Vemurafenib, given orally at the dose of 960 mg twice daily on an outpatient basis for a median of 16 weeks, was generally well tolerated. Drug-related adverse events (mainly arthralgias, skin toxicities, pancreatitis; no myelosuppression) were frequent, but reversible in all patients, and were typically grade 1-2. Only 7 patients developed grade 3 events, and none grade 4 events. Although we did not observe any cutaneous squamous cell carcinomas/keratoachantomas (as reported in BRAF-V600E+ melanoma patients treated with vemurafenib), 3 patients developed 2 basaliomas and 1 superficial melanoma, all treated with a simple excision. Notably, overall response rate was 96% (25/26 patients): 9/26 (34.6%) CRs and 16/26 (61.4%) PRs, obtained after a median of 8 and 9 weeks respectively. CR and PR patients included 1 and 5 primary refractory ones, respectively, as well as 4 and 10 not responding to the last prior treatment, respectively. In all CR patients immunohistochemistry showed minimal residual disease (≤10%) at the end of treatment. Six of 9 (67%) CR patients enjoyed normal blood counts at a median of 13 (range 12-15) months from the end of treatment (see Figure): 3 of these 6 patients showed no morphological evidence of HCL in the bone marrow biopsy (complying with a continuous CR) at 12, 13 and 15 months, respectively, whereas the other 3 lost the bone marrow CR status, all at 12 months. The remaining 3/9 CR patients (33%) developed a mild cytopenia (N ~1000/mmc or PLT ~80000/mmc) 5, 9 and 12 months post-treatment, respectively: in the 2nd patient the cytopenia remained stable until the last follow-up at 15 months, whereas in the other two cases it worsened requiring therapy 9 and 18 months post-treatment, respectively (see Figure). These two latter patients were recently retreated with vemurafenib for 12 and 4 weeks, and obtained a PR and a second CR. Among the 16 PR patients, 5 (31%) mantain normal blood counts at a median of 12 (range 8-17) months post-treatment (see Figure). The other 11 PR patients developed cytopenia(s) after 3 months of median follow-up (range 5-10): in 6 patients (38%) no anti-leukemic therapy was started at a median of 9 (range 6-12) months post-treatment, whereas in the remaining 5 cases (31%) cytopenia(s) worsened requiring therapy at a median of 8 (range 5-11) months of follow-up (see Figure). Four of these latter 5 patients were retreated with vemurafenib for 12 weeks: 3 cases had a minor response and the last one witnessed a second PR that lasted less than the first PR (3 versus 9 months). CONCLUSIONS: In heavily pre-treated HCL patients, a short oral course of vemurafenib was safe, and proved quickly and highly active. Retreatment with vemurafenib was able to reinduce remissions in patients relapsing after a CR, but was less effective in patients relapsing after a PR. Figure 1 Figure 1. Disclosures Off Label Use: Off-label use of vemurafenib in hairy cell leukemia will be discussed as part of a clinical research protocol..

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A Rare Case of Hairy Cell Leukemia with Unusual Loss of CD123 Associated with COVID-19 at the Time of Presentation

Case Reports in Oncology ◽

10.1159/000512830 ◽

2020 ◽

Vol 13 (3) ◽

pp. 1430-1440

Author(s):

Samah Kohla ◽

Feryal A. Ibrahim ◽

Mahmood B. Aldapt ◽

Hesham ELSabah ◽

Shehab Mohamed ◽

...

Keyword(s):

Bone Marrow ◽

Cancer Patients ◽

Hairy Cell Leukemia ◽

Bone Marrow Examination ◽

Assisted Ventilation ◽

Braf V600e ◽

Leukemic Cells ◽

Hairy Cell ◽

Cell Leukemia ◽

First Case

Coronavirus disease 2019 (COVID-19) pandemic has been a serious threat and has been reported with different presentations and complications. Older age, along with comorbidities such as diabetes, hypertension, or cardiac disease, increases the risk factors for COVID-19 severity and death [N Engl J Med. 2020;382(18):1708–20 and Lancet Respir Med. 2020 05;8(5):475–81]. It is proposed that cancer patients have a significantly higher incidence of severe incidents including admission to the intensive care unit, the necessity for assisted ventilation, and even death after catching the virus compared with non-cancer patients [Lancet Oncol. 2020;21(3):335–7]. It is also described that cancer patients appear to be twice as likely to contract infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) [JAMA Oncol. 2020;6(7):1108–10]. Hairy cell leukemia (HCL) is a rare B-cell lymphoproliferative disorder, with patients typically presenting with cytopenias, marked splenomegaly in 80–90% of patients, circulating leukemia cells, bone marrow infiltration and the presence of BRAF V600E somatic mutation [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Leukemic cells classically have central nuclei and abundant cytoplasm with hairy-like projections and express CD11c, CD25, CD103, and CD123 [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Loss of CD123 in HCL has been rarely reported in the literature [Am J Hematol. 2019;94(12):1413–22]. We describe a unique case of a COVID-19-positive male who presented with severe respiratory symptoms, deteriorated quickly, and was intubated. Workup of severe progressive pancytopenia and bone marrow examination revealed HCL without splenomegaly and with atypical unusual loss of CD123. To our knowledge, this is the first case of CD123-negative HCL without splenomegaly associated with COVID-19 infection as the initial presentation.

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