Imatinib is effective in some PDGFRA/B-negative hypereosinophilic syndromes: A step closer to unveiling underlying mechanisms.

Hypereosinophilic syndromes (HES) comprise different clonal, reactive, or idiopathic disorders characterized by elevated eosinophil levels and subsequent organ damage. Kim et al. in a multicentre, single-arm, prospective phase II study, treated 32 patients with PDGFRA/B-negative HES with imatinib at the dose of 100-400 mg daily. Respective overall and complete haematological response rates were 46.9% and 18.8%, and the median time to response was 1.5 months. The molecular basis of responses was identified by using whole-exome and whole-transcriptome sequencing in 11 patients. STAT5B::RARA, PAK2::PIGX, and FIP1L1::CHIC2 fusions were identified in responders, whereas RNF130::BRAF and WNK1::KDM5A were identified in non-responders. Imatinib could be a therapeutic option for some, possibly clonal, PDGFRA/B-negative HES. Commentary on: Kim et al. Phase II trial of imatinib mesylate in patients with PDGFRA/B-negative hypereosinophilic syndrome. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19828.

Donor's age influences outcome in haploidentical hematopoietic stem cell transplantation with post-transplant cyclophosphamide - a single center experience.

Haploidentical stem cell transplantation (haplo-SCT) using post-transplantation cyclophosphamide (post-Cy) is considered a reasonable therapeutic option for patients who lack matched donor or who urgently need transplant procedure due to high risk disease. We analyzed the results of haplo-SCT performed in years 2018-2023. Eighty one patients (46 males) at median age of 52 years underwent haplo-SCT using peripheral blood as a stem cell source in most cases. Indications included hematological malignancies (acute leukemias in 88% of cases). In 25 cases (31%) transplantation was performed in relapsed/refractory disease. Majority of patients (61%) presented with very high and high disease risk index (DRI). Conditioning regimens were as follows: nonmyeloablative - 46 cases (57%), myeloablative - in 18 (22%) and reduced intensity - 17(20%). 90% of patients engrafted. All patients received unified immunosuppressive treatment (post-Cy/TAC/MMF). Median follow-up time was 12 months The cumulative incidence of acute and chronic GVHD was 37.5% and 37.6%, respectively. Estimated 2-year overall survival (OS) was 43.1% and donor's age was the only factor influencing survival. The 2-year progression-free survival (PFS) was 42.5%, whereas relapse incidence (RI) - 35%. The cumulative incidence of non-relapse mortality (NRM) was 44% and was mostly due to infections. Haplo-SCT is a feasible treatment option for hematological patients. Younger donor improves post-transplant survival. Strategies to reduce infection-related mortality and relapse rate remain a challenge.

Are we ready for personalized CAR-T therapy?

The future of chimeric antigen receptor T (CAR-T) therapy remains unclear. New studies are constantly being published confirming the efficacy and favorable safety profile of its innovative enhancements. Currently approved CAR-T drugs are manufactured exclusively for a specific patient from the recipient's own cells. This does not close the door to further modifications with subsequent personalization and better adaptation to the individual needs. Bringing such a drug to market would involve raising the already high costs, so it is necessary to lower the existing ones. On the other hand, so-called universal CAR-T are also getting closer to the patient's bed, but its implementation may struggle with multiple challenges, including development of graft-versus-host disease (GvHD) and alloimmunity. However, that off-the-shelf therapy could prove useful as a quick solution for patients in very poor condition or excluded from current therapy due to manufacturing limitations. The introduction of currently tested solutions may undoubtedly change the current paradigm of treatment.

Splenic irradiation for myelofibrosis prior to hematopoietic cell transplantation: A global collaborative analysis.

Splenomegaly is the clinical hallmark of myelofibrosis. Splenomegaly at the time of allogeneic hematopoietic cell transplantation (HCT) is associated with graft failure and poor graft function. Strategies to reduce spleen size before HCT especially after failure to Janus kinase (JAK) inhibition represent unmet clinical needs in the field. Here, we leveraged a global collaboration to investigate the safety and efficacy of splenic irradiation as part of the HCT platform for patients with myelofibrosis. We included 59 patients, receiving irradiation within a median of 2 weeks (range, 0.9-12 weeks) before HCT. Overall, the median spleen size prior to irradiation was 23 cm (range, 14-35). Splenic irradiation resulted in a significant and rapid spleen size reduction in 97% of patients (57/59), with a median decrease of 5.0 cm (95% confidence interval, 4.1-6.3 cm). The most frequent adverse event was thrombocytopenia, with no correlation between irradiation dose and hematological toxicities. The 3-year overall survival was 62% (95% CI, 48%-76%) and 1-year non-relapse mortality was 26% (95% CI, 14%-38%). Independent predictors for survival were severe thrombocytopenia and anemia before irradiation, transplant-specific risk score, higher-intensity conditioning, and present portal vein thrombosis. When using a propensity score matching adjusted for common confounders, splenic irradiation was associated with significantly reduced relapse (p = .01), showing a 3-year incidence of 12% for splenic irradiation versus 29% for patients with immediate HCT and 38% for patients receiving splenectomy. In conclusion, splenic irradiation immediately before HCT is a reasonable approach in patients experiencing JAK inhibition failure and is associated with a low incidence of relapse.

Impact of comorbidities and body mass index on the outcomes of allogeneic hematopoietic cell transplantation in myelofibrosis: A study on behalf of the Chronic Malignancies Working Party of EBMT.

Investigating the evaluation of eligibility for transplant in myelofibrosis (MF): The role of HCT-CI and BMI. HCT-CI emerges as a key prognostic factor, while BMI shows limited impact. This study expands insights for better clinical decision-making in MF allo-HCT.

Allogeneic hematopoietic stem cell transplantation remains a feasible approach for elderly with acute myeloid leukemia: a 10-year experience.

The incidence of AML increases with age. The implementation of reduced intensity conditioning and progress in supportive care enabled to perform allo-HSCT in elderly patients. The main objective of the study was to assess the safety and efficacy of allotransplantation in elderly AML.Forty nine patients (33 males) at median age of 68 years were identified. Data on patients' and transplant's related variables were retrieved from our local transplant registry. Most patients (65%) were transplanted from 10/10-HLA or 9/10-HLA matched unrelated donor, seven patients (14%) received stem cells from matched related donor and ten patients (20%) from haploidentical donor. All patients received reduced-intensity conditioning (RIC). Peripheral blood was a source of stem cells in all patients except one (98%). Acute GVHD developed in 22 patients (44%) with 5 individuals presenting grade III-IV. CMV reactivation was demonstrated in 19 patients (39%) till day + 100. In total, 22 patients (45%) have died. The main causes of death included infectious complications (n = 9), relapse with subsequent chemotherapy resistance (n = 7), steroid-resistant GvHD (n = 4) and other causes (n = 2). Twenty-seven patients (55%) were alive at the last contact, presented full donor chimerism and remained in the complete remission. The probability of OS and relapse-free survival (RFS) were 57% and 81% at 2 years, respectively. Older donor age showed negative impact on relapse. CMV reactivation, the severity of acute graft versus host disease and older donor age negatively influenced survival. Allo-HSCT remains a safe, feasible and effective procedure for elderly AML patients.

Allogeneic hematopoietic cell transplantation in patients with chronic phase chronic myeloid leukemia in the era of third generation tyrosine kinase inhibitors: A retrospective study by the chronic malignancies working party of the EBMT.

Following the introduction of tyrosine kinase inhibitors (TKI), the number of patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for chronic phase (CP) chronic myeloid leukemia (CML) has dramatically decreased. Imatinib was the first TKI introduced to the clinical arena, predominantly utilized in the first line setting. In cases of insufficient response, resistance, or intolerance, CML patients can subsequently be treated with either a second or third generation TKI. Between 2006 and 2016, we analyzed the impact of the use of 1, 2, or 3 TKI prior to allo-HCT for CP CML in 904 patients. A total of 323-, 371-, and 210 patients had 1, 2, or 3 TKI prior to transplant, respectively; imatinib (n = 778), dasatinib (n = 508), nilotinib (n = 353), bosutinib (n = 12), and ponatinib (n = 44). The majority had imatinib as first TKI (n = 747, 96%). Transplants were performed in CP1, n = 549, CP2, n = 306, and CP3, n = 49. With a median follow-up of 52 months, 5-year OS for the entire population was 64.4% (95% CI 60.9-67.9%), PFS 50% (95% CI 46.3-53.7%), RI 28.7% (95% CI 25.4-32.0%), and NRM 21.3% (95% CI 18.3-24.2%). No difference in OS, PFS, RI, or NRM was evident related to the number of TKI prior to allo-HCT or to the type of TKI (p = ns). Significant factors influencing OS and PFS were > CP1 versus CP1 and Karnofsky performance (KPS) score > 80 versus ≤80, highlighting CP1 patients undergoing allo-HCT have improved survival compared to >CP1 and the importance of careful allo-HCT candidate selection.

Double Malignancy and Double Transplant-A Bumpy Road to Success.

The occurrence of secondary neoplasms in adult patients treated with chemotherapy in childhood is not uncommon. Prior chemotherapy is found to be an independent risk factor for the development of secondary malignancies, which are usually associated with a worse prognosis. The presented case is a 35-year-old female patient who was diagnosed with Ewing sarcoma in her late adolescence. The tumor was successfully treated with chemotherapy, but 3 years later she was diagnosed with T-cell lymphoblastic lymphoma. The patient received allogeneic hematopoietic stem cell transplantation (allo-HSCT) from human leukocyte antigen (HLA) matched related donor. The procedure was complicated by grade 2 acute graft-versus-host disease (GvHD) which resolved after implementation of immunosuppressive treatment. However, a year later, the patient developed extensive chronic GvHD (cGvHD) and required reintroduction of immunosuppressants. Prolonged immunosuppressive treatment with tacrolimus led to irreversible kidney failure. After a 2-year period of regular peritoneal dialysis, she was found to be eligible for a kidney transplant from a deceased donor. Now, 15 years after stem cell transplantation and 8 years after kidney transplantation, the patient remains in good condition overall, presenting with symptoms of limited cGvHD. The case described here presents a unique clinical scenario of a female patient who was successfully treated for her double malignancy. Moreover, she underwent effective double transplantations and was eventually found to be cured despite accompanying complications.

Spectacular and Prompt Response to Extracorporeal Photopheresis for Refractory Cutaneous Chronic Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation: A Case Report.

Chronic graft-versus-host disease (cGVHD) is a serious complication after allogenic hematopoietic stem cell transplantation (allo-HSCT), negatively affecting the morbidity and mortality of recipients. Skin involvement is the most common cGVHD manifestation with a wide range of pleomorphic features, from scleroderma to ulcerations and microangiopathic changes. Despite the access to many immunosuppressive drugs, therapy for cGVHD is challenging. Systemic steroids are recommended as the first-line treatment; but, in steroid-resistant patients, extracorporeal photopheresis (ECP) remains one of the subsequent therapeutic options. Here, we present a case report of a 31-year patient suffering from advanced steroid-refractory skin and oral mucosa cGVHD who was spectacularly treated with ECP. It was the first time we observed such "overnight" resolution of the graft-versus-host disease syndrome. The present report proves the important role of ECP in the treatment of steroid-resistant cGVHD, especially when other immunosuppressive therapies have failed.

Hemophagocytic lymphohistiocytosis associated with ocrelizumab treatment in a patient with multiple sclerosis.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a rarely recognized hyperinflammatory condition of high death risk. OBJECTIVE: The objective was to describe a case of HLH in a patient with multiple sclerosis (MS) treated with ocrelizumab. METHODS: Clinical observation, laboratory testing, and use of HLH-2004 criteria for HLH diagnosis. RESULTS: A 32-year-old Caucasian female developed HLH during ocrelizumab treatment. She met six of the eight HLH criteria including fever, splenomegaly, cytopenia, hypertriglyceridemia and hypofibrinogenemia, high serum ferritin level, and low natural killer (NK) cells. CONCLUSION: HLH should be considered in the differential diagnosis in MS patients displaying a fever and malaise syndrome following administration of ocrelizumab.

Impact of spleen size and splenectomy on outcomes of allogeneic hematopoietic cell transplantation for myelofibrosis: A retrospective analysis by the chronic malignancies working party on behalf of European society for blood and marrow transplantation (EBMT).

The role of spleen size and splenectomy for the prediction of post-allogeneic hematopoietic stem cell transplant (allo-HCT) outcome in myelofibrosis remains under debate. In EBMT registry, we identified a cohort of 1195 myelofibrosis patients transplanted between 2000-2017 after either fludarabine-busulfan or fludarabine-melphalan regimens. Overall, splenectomy was performed in 202 (16.9%) patients and its use decreased over time (28.3% in 2000-2009 vs 14.1% in 2010-2017 period). By multivariate analysis, splenectomy was associated with less NRM (HR 0.64, 95% CI 0.44-0.93, P = .018) but increased risk of relapse (HR 1.43, 95% CI 1.01-2.02, P = .042), with no significant impact on OS (HR 0.86, 95% CI 0.67-1.12, P = .274). However, in subset analysis comparing the impact of splenectomy vs specific spleen sizes, for patients with progressive disease, an improved survival was seen in splenectomised subjects compared to those patients with a palpable spleen length ≥ 15 cm (HR 0.44, 95% CI 0.28-0.69, P < .001), caused by a significant reduction in NRM (HR 0.26, 95% CI 0.14-0.49, P < .001), without significantly increased relapse risk (HR 1.47, 95% CI 0.87-2.49, P = .147). Overall, despite the possible biases typical of retrospective cohorts, this study highlights the potential detrimental effect of massive splenomegaly in transplant outcome and supports the role of splenectomy for myelofibrosis patients with progressive disease and large splenomegaly.

Allogeneic peripheral blood stem cell transplantation with anti-thymocyte globulin versus allogeneic bone marrow transplantation without anti-thymocyte globulin.

We compared severe graft-versus-host-disease (GvHD) free and relapse-free survival and other transplantation outcomes of acute myeloid leukemia (AML) patients given bone marrow (BM) without anti-thymocyte globulin (ATG) versus peripheral blood stem cells (PBSC) with ATG after myeloablative conditioning. In the cohort of patients receiving grafts from a human leukocyte antigen (HLA)-matched sibling donor, patients given PBSC with ATG (n=1,021) and those given BM without ATG (n=1,633) presented comparable severe GvHD-free relapse-free survival (GRSF)(hazard ratio [HR]=0.9, 95% confidence interval [CI]: 0.8-1.1, P=0.5) and overall survival (HR=1.0, 95% CI: 0.8-1.2, P=0.8). They had however, a lower incidence of chronic GvHD (cGvHD) (HR=0.7, 95% CI: 0.6-0.9, P=0.01). In the cohort of patients receiving grafts from HLA-matched unrelated donor , patients given PBSC with ATG (n=2,318) had better severe GvHD-free and relapse-free survival (GRFS) than those given BM without ATG (n=303) (HR=0.8, 95% CI: 0.6-0.9, P=0.001). They also had a lower incidence of cGvHD (HR=0.6, 95% CI: 0.5-0.8, P=0.0006) and better overall survival (HR=0.8, 95% CI: 0.6-1.0, P=0.04). In summary, these data suggest that PBSC with ATG results in comparable (in the case of sibling donor) or significantly better (in the case of unrelated donor) severe GRFS than BM without ATG in patients with AML in complete remission receiving grafts after myeloablative conditioning.

Pre-transplant FLT3/ITD status predicts outcome in FLT3-mutated acute myeloid leukemia following allogeneic stem cell transplantation.

Acute myeloid leukemia (AML) with fetal liver tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) is associated with poor prognosis, and allogeneic stem cell transplantation (Allo-SCT) seems to be the preferred therapeutic approach. However, the predictors of post-transplant outcomes were not well-defined. The aim of the study was to evaluate the significance of FLT3/ITD mutation by polymerase chain reaction as minimal residual disease (MRD) marker of outcomes after transplantation. We identified 43 patients (28 females and 15 males) with FLT3-mutated AML at the median age of 45 years who were allografted between 2009 and 2019. Hematological status at transplant was as follows: the first complete remission (CR1) in 29 patients, CR2 in 5, and 9 patients were transplanted in marrow aplasia (MA). Twenty-seven patients were FLT3 MRD negative at transplant. Median time from diagnosis to transplant was 16.7 months. Post-allograft CR rate was 88%. The relapse incidence (RI) was lower for patients who were FLT3 MRD negative at transplant when compared with those with FLT3 MRD positivity (41% vs 59%; p = 0.01). The patients who eradicated FLT3/ITD at day + 30 after transplant had lower RI than those with detectable FLT3/ITD (23% vs 76%; p = <0.001). The 2-year LFS and OS were 53% and 54%, with the median OS and LFS of 28 months and 27 months, respectively. Patients with CR1/2 and FLT3 MRD(-) had a 2-year OS of 80%. The FLT3 MRD negativity at transplant prolonged LFS in multivariate analysis (HR 5.3 95%CI 1.97-14.2); p < 0.001), whereas FLT3 MRD negativity and unrelated donor predicted favorable OS.

Allogeneic transplantation for high-risk chronic lymphocytic leukemia-a summary of a 16-year experience.

In the pathway inhibitor era, the number of allogeneic stem cell transplantation (ASCT) for chronic lymphocytic leukemia (CLL) continues to decrease and this approach should be offered only after careful risk-benefit assessment. Nevertheless, ASCT still remains only curative therapeutic modality for CLL, especially in countries with limited access to novel agents. Thirty patients with CLL at median age of 42 years at diagnosis (range 29-64) underwent ASCT between years 2002 and 2018. Thirteen patients were transplanted in complete remission (CR), ten patients achieved partial response (PR), and seven had stable disease. The median time from diagnosis to transplant was 4 years (range 0.5-12). Twenty-three patients received HLA-matched related donor stem cell grafts, and seven patients received either matched unrelated donor or HLA-mismatched grafts. Reduced intensity conditioning (RIC) and myeloablative regimen (MAC) were used in 24 and 6 patients, respectively. Mortality to day + 100 after transplant was 16% (8% for RIC only). Acute and chronic graft versus host disease (GVHD) developed in 40% and 63% of patients, respectively. Fifteen patients relapsed or progressed after transplant. Thirteen patients (43%) are alive at last follow-up and 10 (77%) remain in clinical CR. Median follow-up for survivors was 6.8 years (range 0.4-15.2). Three-year progression-free and overall survivals were 56% and 60%, respectively. These outcomes were better for patients who received RIC conditioning: 64% and 72%, respectively. CR at transplant was found to have favorable impact on post-allograft survival. RIC should be preferred over MAC. ASCT may remain a valuable option for some CLL patients.

Safety and outcome of allogeneic stem cell transplantation in myelofibrosis.

OBJECTIVES: We evaluated the safety and outcome of allo-HSCTs in myelofibrosis (MF). METHODS: A total of 27 patients with primary (n = 20) or secondary (n = 7) MF, aged 51 (21-63) yr, transplanted from HLA-matched related (59%) or unrelated (41%) donors were analyzed. Conditioning was reduced in 26 and myeloablative in one patient; and ATG was used in 25. Sources of stem cells were as follows: peripheral blood (21), bone marrow (4) or both (2). RESULTS: Prognostic factors that adversely affected overall survival (OS) in the multivariate analysis were as follows: recipient age >45 yr (HR = 10.55, P = 0.025) and unrelated donor (HR=3.73, P = 0.026). Post-transplant transfusion dependence adversely affected OS in the univariate analysis: dependence from either both RBCs and platelets (HR = 33.26, P = 0.001) or from either of them (HR = 10.53, P = 0.043). Of 16 JAK2V617F-positive patients evaluated post-transplant, it was eradicated in 69% and decreased in 25%. Acute GVHD III-IV developed in 19% and extensive chronic GVHD in 26% of patients; the relapse in four patients was treated with second allo-HSCT. Spleen decreased in all evaluated patients (n = 24). Fibrotic changes improved or disappeared in 80% of evaluated patients (n = 10). CONCLUSIONS: Allo-HSCT may prolong survival, provide disease regression and improve quality of life in MF, especially in patients ≤ 45 yr transplanted from matched related donors. Achieving transfusion independence post-transplant indicates the favorable outcome.

Central nervous system involvement by multiple myeloma: A multi-institutional retrospective study of 172 patients in daily clinical practice.

The multicenter retrospective study conducted in 38 centers from 20 countries including 172 adult patients with CNS MM aimed to describe the clinical and pathological characteristics and outcomes of patients with multiple myeloma (MM) involving the central nervous system (CNS). Univariate and multivariate analyses were performed to identify prognostic factors for survival. The median time from MM diagnosis to CNS MM diagnosis was 3 years. Thirty-eight patients (22%) were diagnosed with CNS involvement at the time of initial MM diagnosis and 134 (78%) at relapse/progression. Upon diagnosis of CNS MM, 97% patients received initial therapy for CNS disease, of which 76% received systemic therapy, 36% radiotherapy and 32% intrathecal therapy. After a median follow-up of 3.5 years, the median overall survival (OS) from the onset of CNS involvement for the entire group was 7 months. Untreated and treated patients had median OS of 2 and 8 months, respectively (P < 0.001). At least one previous line of therapy for MM before the diagnosis of CNS disease and >1 cytogenetic abnormality detected by FISH were independently associated with worse OS. The median OS for patients with 0, 1 and 2 of these risk factors were 25 months, 5.5 months and 2 months, respectively (P < 0.001). Neurological manifestations, not considered chemotherapy-related, observed at any time after initial diagnosis of MM should raise a suspicion of CNS involvement. Although prognosis is generally poor, the survival of previously untreated patients and patients with favorable cytogenetic profile might be prolonged due to systemic treatment and/or radiotherapy. Am. J. Hematol. 91:575-580, 2016. © 2016 Wiley Periodicals, Inc.

Autologous hematopoietic stem cell transplantation (AHSCT) for aggressive multiple sclerosis - whom, when and how.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that leads to an inflammatory process resulting in demyelination and axonal degeneration. The most common form of MS is the relapsing-remitting MS (RRMS) characterized by the presence of numerous relapses. After few years of disease course, 90% of those patients eventually develop a secondary progressive form. About 10% of patients may suffer from a slowly progressive MS form - the primary progressive. The current treatment of RRMS includes immunomodulatory and immunosuppressive agents, which are effective, but usually in earlier and more benign forms. The immunomodulatory treatment has limited efficacy in aggressive forms of RRMS, and relapses occur despite treatment continuation. AHSCT should be considered as a therapeutic approach for patients with aggressive relapsing-remitting and aggressive progressive MS who failed conventional therapy. The mechanism of action of AHSCT for MS results from resetting the aberrant patient's immune system and eliminating the autoreactive T-lymphocytes. AHSCT can serve as an effective and safe procedure only when strict neurological eligibility criteria are adhered. The procedure should be performed in highly specialized hematological centers. The aim of our paper is to summarize the current eligibility criteria for AHSCT in MS patients as well as to present data on efficacy and safety of this approach.

Fungal colonization of the respiratory tract in allogeneic and autologous hematopoietic stem cell transplant recipients: a study of 573 transplanted patients.

BACKGROUND: Fungal colonization and infections remain a major cause of infection morbidity and mortality following hematopoietic stem cell transplantation (HSCT) in patients with hematological malignancies. The aim of this study was to analyze the spectrum of fungal microflora of the respiratory tract (oral cavity, pharynx, epiglottis, and sputum) in patients undergoing HSCT and to evaluate the relationship between HSCT type and incidence of mycotic colonization and infections. MATERIAL/METHODS: Retrospective analysis of fungal isolates collected from the respiratory tract (oral cavity, pharynx, epiglottis, and sputum) of 573 patients undergoing HSCT was performed. RESULTS: The overall rate of fungal colonization in patients undergoing HSCT was 8.7%. Patients undergoing allogeneic HSCT were statistically significantly more often colonized (12.95%) compared to autologous HSCT recipients (4.7%). Colonizing cultures were mainly C. albicans and C. krusei, and sporadically C. glabrata, C. famata, Aspergillus spp. and Saccharomyces cerevisiae. C. albicans was the most frequent species found in isolates from the pharynx, sputum, and oral cavity collected from patients undergoing HSCT. Aspergillosis was more common after allogeneic than after autologous HSCT. The pharynx was the most frequently colonized site. CONCLUSIONS: Allogeneic HSCT recipients are more susceptible to fungal infections compared to the autologous group. Selection of species during prophylaxis and antifungal therapy requires developing more effective prevention and treatment strategies based on new antifungal drugs and microbe-specific diagnoses.

The sudden onset of mastocytosis in the course of venom-induced anaphylactic reaction in a patient with myelodysplastic syndrome.

Mastocytosis is a disease resulting from a proliferation of clonal, abnormal mast cells in tissues and organs, defined as Philadelphia-negative myeloproliferative neoplasm. We present a male patient with clinically, morphologically and immunohistochemically confirmed mastocytosis with preceding myelodysplastic syndrome, occurred after wasp bite in the course of anaphylactic reaction. The propensity to hymenoptera venom-induced anaphylaxis and the presence of an increased population of atypical mast cells in bone marrow found after anaphylactic shock may suggest the possible relationship between hymenoptera venom allergy and anaphylaxis and the development of mastocytosis of unusual course in a predisposed person.