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The objectives of this article are to present a case of type II cryoglobulinemic vasculitis, explain why mucosa-associated lymphoid tissue (MALT) lymphoma is an unusual cause of type II cryoglobulins and to discuss the aetiology, epidemiology, pathophysiology and treatment of cryoglobulinemic vasculitis. A 67-year-old woman presented with 4 months of weight loss, intermittent epistaxis and a purpuric skin rash. Prior to presentation, she was found to have an elevated rheumatoid factor. Further investigation revealed an acute kidney injury and elevated type II cryoglobulins suspicious for cryoglobulinemic vasculitis, which was confirmed by kidney biopsy. Additional workup for the weight loss included biopsy of newly found splenomegaly. Pathology revealed MALT lymphoma, a rare cause of type II cryoglobulinemic vasculitis. Successful medical therapy required treating the underlying malignancy with rituximab and high-dose steroids. After initial resolution of symptoms with this regimen, the patient’s vasculitis worsened, which was thought to be secondary to undertreatment of the lymphoma. Bendamustine was added to further treat the lymphoma, after which the patient recovered and was able to discharge without recurrence of symptoms at 6 months.

Purpose Over 1 billion doses of COVID-19 vaccines have been already administered across the United States, the United Kingdom and the European Union at the time of writing. Furthermore, 1.82 million booster doses have been administered in the US since 13th August, and similar booster programmes are currently planned or under consideration in the UK and the EU beginning in the autumn of 2021. Early reports showed an association between vaccine administration and the development of ipsilateral axillary and supraclavicular lymphadenopathy, which could interfere with the diagnosis, treatment and follow-up of breast cancer patients. In this paper, we review the available evidence on vaccine-related lymphadenopathy, and we discuss the clinical implications of the same on breast cancer diagnosis and management. Methods A literature search was performed - PubMed, Ovid Medline, Scopus, CINHAL, Springer Nature, ScienceDirect, Academic Search Premier and the Directory of Open Access Journals were searched for articles reporting on regional palpable or image-detected lymphadenopathy following COVID-19 vaccination. Separately, we compiled a series of case studies from the University Hospitals of Derby and Burton, United Kingdom and the Mayo Clinic in Minnesota, United States of America, to illustrate the impact that regional lymphadenopathy post-COVID-19 vaccination can have on the diagnosis and management of patients being seen in diagnostic and therapeutic breast clinics. Results From the literature search, 15 studies met the inclusion criteria (n = 2057 patients, 737 with lymphadenopathy). The incidence of lymphadenopathy ranged between 14.5% and 53% and persisted for >6 weeks in 29% of patients. Conclusions Clinicians managing breast cancer patients should be aware that the COVID-19 vaccination may result in regional lymphadenopathy in a significant number of patients, which can result in unnecessary investigations, treatment and increased patient anxiety. An accurate COVID-19 vaccination history should be collected from all patients where regional lymphadenopathy is a clinical and/or an imaging finding and then combined with clinical judgement when managing individual cases.

Langerhans cell histiocytosis (LCH) is a histiocytic neoplasm that can involve the lungs as single system (LCH-SSL) or multisystem disease (LCH-MSL). The role of full-body radiographic staging to determine whether patients have LCH-SSL or LCH-MSL is unclear. Long-term outcomes of LCH-SSL versus LCH-MSL and multisystem without lung involvement (LCH-MSNL) are unknown. A retrospective study of adult LCH patients seen at our center from January 2000 to 2020 was performed. In Part 1, we addressed utility of whole-body staging imaging among those presenting with isolated pulmonary signs or symptoms. Staging was defined as fluorodeoxyglucose positron emission tomography-computed tomography (CT) or whole-body CT obtained within 3 months of diagnosis. In Part 2, we examined the frequency of developing extra-pulmonary disease over time and mortality in patients with LCH-SSL. In Part 3, we compared the overall survival of LCH-SSL, LCH-MSL, and LCH-MSNL. Part 1: 240 patients with LCH were identified. A total of 112 (47%) had pulmonary signs or symptoms at presentation. Thirty-four (30%) underwent radiographic staging and only one showed evidence of extra-pulmonary disease. Part 2: 108 (45%) were LCH-SSL. Median follow-up duration of 4.5 years (95% confidence interval [CI]: 2.9-6.0). None developed extra-pulmonary disease. Part 3: 5-year survival: 94% (95% CI: 84%-98%) for LCH-SSL, 78% (95% CI: 59%-90%) for LCH-MSL, and 75% (95% CI: 53%-89%) for LCH-MSNL. LCH patients presenting with isolated pulmonary signs or symptoms rarely have extra-pulmonary involvement at the time of diagnosis and generally do not develop extra-pulmonary progression. LCH-SSL has the best overall survival, while LCH-MSL and LCH-MSNL have similar clinical outcomes.

BACKGROUND Hospitalized patients with hematologic malignancies are medically complex and commonly affected by dermatologic conditions. METHODS Retrospective chart review from January 1, 2014, to December 31, 2018, at Rochester Methodist Hospital (Rochester, Minnesota, USA). Patients hospitalized on hematology and BMT services receiving dermatology consultation were included. RESULTS In all, 578 consultations (63% male, median age 61 years) were reviewed. Drug reactions (22%), infection (17%), and malignant neoplasm (10%) accounted for nearly half of diagnoses. Exanthematous drug reaction (10%), graft-versus-host disease (7%), and lymphoma or leukemia cutis (6%) were the commonest individual diagnoses. There were significantly more drug reactions in severe neutropenia (33.2% vs. 15.0%), neutrophilic dermatoses in myeloid neoplasm (5.2% vs. 0.3%), and viral infection in lymphoid neoplasm (8.3% vs. 1.2%). Consultation frequently altered treatment (68%), diagnostic workup (63%), and the primary service's initial diagnostic impression (53%). Biopsies were performed in 52% of consultations and helped secure a diagnosis 73% of the time. A total of 16.4% of consultations did not receive a definitive final diagnosis, and 18.5% were resolved in one visit. CONCLUSION This is the largest study to date of hospital dermatology consultation in hematology patients. Biopsies are utilized frequently and are diagnostically useful. The complexity of this patient population is evidenced by the fact that a final diagnosis remains elusive in a number of cases despite the multiple visits required for the vast majority of consultations. Nevertheless, dermatology consultation alters diagnosis and treatment in the majority of patients, highlighting the critical role dermatologists have in the care of these patients.

To evaluate the clinical presentation, treatment, and outcomes in adult patients with histiocytic disorders with ocular, orbital, optic nerve, or cavernous sinus involvement.Observational, retrospective chart review.Adult patients (age ≥ 18 years) at Mayo Clinic from January 1, 1996, to July 1, 2021, with histiocytic disorders. Inclusion criteria were (1) histiocytic disorder by biopsy and appropriate clinical phenotype; (2) available medical records; and (3) ocular, orbital, optic nerve, or cavernous sinus involvement.Retrospective chart review.Response to therapy, measured in clinical and radiographic impact.Thirty-two patients were identified: 7 with Langerhans cell histiocytosis (LCH); 15 with Erdheim-Chester disease (ECD); 1 with mixed LCH/ECD phenotype; 8 with Rosai-Dorfman disease (RDD); and 1 with mixed RDD/ECD phenotype. Ophthalmologic involvement was part of the initial presentation in 69% of patients (22/32). Eyelid edema (13/32, 41%) and proptosis (12/32, 38%) were the most frequent presentations. Isolated orbital or cavernous sinus involvement was present in 3 of 7 patients with LCH and 1 of 8 patients with RDD. Optic nerve sheath involvement was present in 2 of 7 LCH patients, 14 of 15 ECD patients, and 1 RDD/ECD patient. Diffuse (75%) orbital involvement was seen in 12 of 15 ECD patients and 1 of 7 LCH patients. Ocular involvement was seen in 1 of 15 ECD patients, 6 of 8 RDD patients, and 1 of 1 mixed RDD/ECD patient. The cavernous sinuses were involved in 1 of 7 LCH patients, 5 of 15 ECD patients, and both mixed phenotype patients. Visual acuity was affected in 14 patients (14/24, 58%) with a median logarithm of the minimum angle of resolution visual acuity of 0.1 (range, -0.12 to 3). BRAF V600E mutations were found in 75% (3/4) of LCH patients and 91% (10/11) of ECD patients. Patients received a variety of treatment, and response was variable across disease types.Orbital involvement was more commonly seen in LCH and ECD, whereas ocular involvement was more common in RDD. Visual acuity may be impacted from ocular involvement or compression of the optic nerve with diffuse orbital involvement.

Langerhans cell histiocytosis (LCH) is a rare histiocytic neoplasm. To date, there is a lack of U.S. Food and Drug Administration–approved treatments in adult LCH to establish optimal first-line therapy. We conducted a retrospective, single-center case series evaluating the use of BRAF inhibitors in adult patients with BRAFV600E- LCH proven by biopsy. Our case series is the first to report the use of BRAF inhibitors as first-line therapy in adults with LCH. We also report the efficacy with single-agent dabrafenib in adult LCH. All but one of our patients had favorable response to targeted therapy.

Erdheim-Chester disease (ECD) is a rare histiocytic neoplasm derived from the macrophage/dendritic cell lineage and harbors the BRAFV600E mutation in 50–60% of patients [1]. The U.S. Food and Drug ...

INTRODUCTION: An algorithmic approach, termed the prolonged clot time profile (PROCT), consisting of initial screening with prothrombin time (PT) and activated partial thromboplastin time (aPTT), reflexive mixing studies if indicated, and follow-up assays depending on initial testing results, offers an efficient approach to delineate the etiology of a prolonged PT/aPTT. Herein, we present the outcomes of the PROCT in the outpatient setting. METHODS: In this retrospective study, we reviewed medical records of consecutive outpatients who had prolonged PT and/or aPTT noted in the routine coagulation laboratory and who had PROCT ordered in our institutional Special Coagulation Laboratory between 2010 and 2017. RESULTS: One hundred and six patients, median age 55 years (IQR 30-67), met our study criteria. Twenty-nine patients had normal PT/aPTT, while 77 had persistent abnormalities and underwent reflexive testing. A prolonged PT, aPTT, or PT and aPTT was noted in 27 (35%), 27 (35%), and 23 (30%) respectively. Forty-nine (64%) had an acquired condition, 17 (22%) had a congenital condition, 7 (9%) had unclear etiology, and 4 (5%) were the result of laboratory artifact. The most common known cause of an isolated prolonged PT in our study was vitamin K deficiency in 8 (10%), the most common cause of an isolated prolonged aPTT was lupus anticoagulant in 4 (5%), and the most common cause of prolonged PT and aPTT was liver disease in 11 (14%). CONCLUSION: Prolonged PT/aPTT have a wide range of causes, including artifactual prolongation or abnormalities in secondary hemostasis due to both inherited and acquired conditions.

NT-proBNP, soluble ST2 (sST2), and galectin-3 are biomarkers of cardiac dysfunction that have been proposed as identifiers of patients experiencing asymptomatic cardiac dysfunction after anthracycline-based chemotherapy. This study aimed to compare the proportion of breast cancer (BC) survivors with elevated serum levels of these three putative biomarkers by prior receipt of anthracycline (yes vs. no). Five-hundred-eighty survivors of BC who had received anthracycline-based chemotherapy were matched by age and time between diagnosis and serum storage to 580 who had not. Cardiac biomarker levels were analyzed using immunoassays. Analyses were carried out using linear and logistic regression models. Anthracycline recipients had higher values of NT-proBNP than non-recipients (mean 116.0 ng/L vs. 97.0 ng/L, respectively; p < 0.001). Values for ST2 and galectin-3 did not significantly differ by receipt of anthracycline. After further adjustment for age at breast cancer diagnosis, ethnicity, and receipt of trastuzumab, associations between receipt of anthracycline and higher NT-proBNP persisted (p < 0.001), showing that NT-proBNP may be a biomarker of cardiovascular toxicity after receipt of anthracycline-based chemotherapy. Further research to assess the clinical utility of NT-proBNP testing after receipt of anthracycline is recommended. sST2 and galectin-3 do not appear to differentiate between anthracycline recipients and non-recipients amongst breast cancer survivors.

Background Cutaneous squamous cell carcinomas (CSCC) involving the head and neck are common, but initial presentation or recurrence limited to the cranial nerves is rare. Methods We conducted a retrospective study of 21 patients with clinical perineural invasion (PNI) from CSCC and no measurable disease by RECIST 1.1. Patients treated with radiotherapy or chemoradiotherapy were included. Results The median time from symptom onset until diagnosis was 13.0 months (2.6-83.1). All patients received radiotherapy. Fourteen received concurrent systemic therapy. The median follow-up time was 30.5 months (1.1-106.0). Ten patients recurred, with the majority being locoregional. The 2-year overall survival rate was 85%. The median progression-free survival (PFS) was 21.5 months with an estimated 2-year PFS of 44.5% (95%CI: 22.3-66.8). Conclusions CSCCs with clinical PNI alone are difficult to diagnose and can have a long interval between appearance of symptoms and diagnosis. They can successfully be treated with chemoradiotherapy. However, many patients still suffer from locoregional recurrences.

Langerhans cell histiocytosis (LCH) is a rare histiocytic neoplasm. To date, there is a lack of U.S. Food and Drug Administration–approved treatments in adult LCH to establish optimal first‐line therapy. We conducted a retrospective, single‐center case series evaluating the use of BRAF inhibitors in adult patients with BRAF (V600E)‐ LCH proven by biopsy. Our case series is the first to report the use of BRAF inhibitors as first‐line therapy in adults with LCH. We also report the efficacy with single‐agent dabrafenib in adult LCH. All but one of our patients had favorable response to targeted therapy.

Background: Erdheim-Chester disease (ECD) is characterized by multi-organ infiltration of clonal histiocytes bearing activating mutations predominantly in the MAPK pathway. The diagnosis of ECD is clinico-pathologic; histopathologic findings alone are often non-specific. Characteristic pathognomonic finding of ECD is the symmetric osteosclerosis of the distal femur and proximal tibia/fibula, seen in >90% of cases, and referred to herein as classic ECD (C-ECD). There is a paucity of data on the phenotypic and mutational differences between C-ECD and non-classic ECD (NC-ECD). Determining phenotypic patterns may allow for earlier suspicion and diagnosis. Methods: Patients who met the revised ECD criteria proposed by Haroche J et al (Blood 2020;135:1311-1318) and had full body imaging that included the lower legs (18-FDG-PET/CT or CT/bone scan) were included. ECD diagnosis was made when >1 major criteria plus >1 minor criteria were present. Major criteria: 1) symmetric meta-diaphyseal osteosclerosis in legs; 2) "hairy kidneys"; "coated aorta", right atrial pseudotumor, xanthelasma, exophthalmos; or osteosclerosis of paranasal sinuses. Minor criteria: 1) histologic finding of typical foamy histiocytes (CD68+/CD163+/CD1a-) associated with fibrosis; 2) mutation/gene fusion of BRAF, CSF1R, or MAPK/PI3K pathways. We compared the organ involvement and BRAF V600Emutational status between C-ECD and NC-ECD. Results: A total of 105 patients were included. The median age at diagnosis was 57 years (range, 38-81) and most were males (62%). Majority had 18-FDG-PET/CT (83%) and BRAF V600E testing (65%). The main organ systems involved were skeletal (83%), renal (64%), adrenal (44%), and pulmonary (42%). Central diabetes insipidus (DI), "hairy kidneys", and "coated aorta" were present in 27 (26%), 54 (51%), and 44 (42%) patients, respectively. Among those tested, BRAF V600E mutation was found in 48/67 (72%) by immunohistochemistry. In our cohort, most patients (n=87. 83%) had C-ECD. NC-ECD had significantly lower number of organs/systems involved compared with C-ECD (median 3 vs 6, p=0.002). C-ECD had significantly higher rates of involvement of paranasal sinuses (51%/7%, p=0.002), DI (26%/0%, p=0.02), and similar rates of lung (44%/43%), cardiac (34%/14%), and skin (14%14%) involvement when compared to NC-ECD. BRAF V600E was significantly more common in C-ECD (88%/30%, p=0.004). Thirty-nine (37%) patients underwent next generation sequencing, of whom 33 (31%) had successful testing. In C-ECD, 3 patients had mutations other than BRAF V600E, these included: NRAS, MAP2K1, and MEF2C-FLT3 fusion. In NC-ECD, 5 patients had mutations other than BRAF V600E, these included: MAP2K1, KRAS, and NF1. Conclusions: Our study suggests distinct differences in clinical presentation and molecular findings exist between C-ECD and NC-ECD. C-ECD has a higher degree of organ involvement and harbor BRAF V600E more frequently than NC-ECD. Further analysis of histopathologic findings and outcomes in this cohort may provide insights into these ECD subsets that can optimize future management of this disease. Figure 1: Sites of involvement of classical Erdheim-Chester Disease (C-ECD) versus non-classical Erdheim-Chester Disease (NC-ECD) Figure 1 Figure 1. Disclosures Vassallo: Bristol-Myers-Squibb: Research Funding; Sun Pharma.: Research Funding; Pfizer: Research Funding. Tobin: Mayo Clinic Center for MS and Autoimmune Neurology: Research Funding; Mallinckrodt Pharmaceuticals: Research Funding; National Institutes of Health: Research Funding. Bennani: Verastem: Other: Advisory Board; Purdue Pharma: Other: Advisory Board; Vividion: Consultancy, Other: Advisory Board; Daichii Sankyo Inc: Other: Advisory Board; Kyowa Kirin: Other: Advisory Board.

Background: Langerhans cell histiocytosis (LCH) is the most common histiocytic disorder that is now recognized as a neoplasm by the World Health Organization. It is generally classified based on the site and extent of disease involvement (single system or multisystem). Pulmonary LCH (pLCH), an uncommon interstitial lung disease associated with smoking, often presents as isolated pulmonary disease. It is unclear whether patients with clinically isolated pLCH have extra-pulmonary lesions at diagnosis or during the course of their disease. The role of [18F] fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET-CT) in the staging of pLCH remains unclear. Our study aims to better characterize the utility of radiographic staging studies at time of diagnosis and prevalence of extrapulmonary disease at follow up in pLCH. Methods: We conducted a retrospective study of patients presenting with clinical findings consistent with isolated pLCH seen at the Mayo Clinic from January 2000 to January 2020. All patients had a diagnosis of pLCH determined by chest imaging studies [computed tomography (CT) or high-resolution CT (HRCT)] or by histopathologic findings from surgical or transbronchial lung biopsy. Histopathologic findings for the diagnosis of pLCH required the presence of Langerhans cells (S100+/CD1a+/Langerin+). Patients were excluded if they had clinically apparent extra-pulmonary organ involvement at the time of diagnosis. BRAF V600E mutation was determined by immunohistochemistry (IHC) or cell-free DNA (cfDNA). Staging was defined as FDG-PET-CT or whole body CT imaging obtained within 3 months of diagnosis of pLCH. Extra-pulmonary LCH involvement was determined by imaging characteristics or by histopathologic findings. Descriptive statistics and overall survival (OS) were analyzed with JMP software, version 14 (SAS Institute Inc., Cary, NC). Results: A total of 112 patients with clinically isolated pLCH were identified. The median age at diagnosis was 45 years (range 21-73), and 48 (43%) were male. The majority (n=110, 99%) were former or current smokers with a median pack year of 25 (range 1-57). Three (3%) patients were noted to have occupational industrial exposure. Nine patients had a history of another cancer prior to their diagnosis and staging of pLCH [lung (n=4), breast (n=2), neuroendocrine (n=2), thyroid (n=1)]. Presenting symptoms included dyspnea on exertion 49 (44%), cough 18 (16%), chest pain 14 (13%), and 29 (28%) were incidentally discovered on imaging studies. On HRCT, the following characteristics were observed: 42 (38%) cystic, 32 (29%) cystic and nodular, 37 (33%) nodular, 1 (5 years) follow up data were available for 23 (29%), and none developed extra-pulmonary disease as determined by clinical notes or imaging studies. No patient had evidence of new extra-pulmonary involvement or second malignancy at the time of last known follow-up. After a median follow-up duration of 2.4 years (95% CI: 1.5-3.6, range: 0.1-17) ten (9%) patients died, of which 5 died of pLCH related complications. The median OS for entire cohort was 15 years (95% CI 9.1-not reached, Figure 1). Conclusion: Our study shows that adult patients with clinically isolated pLCH rarely present with extra-pulmonary manifestations at diagnosis or at follow up. These findings suggest a limited role of routine radiographic staging studies in pLCH unless clinically indicated. Studies on longer follow up of this cohort would provide further insights into the natural history of pLCH and are underway. Disclosures Bennani: Purdue Pharma: Other: Advisory Board; Verastem: Other: Advisory Board; Kite/Gilead: Research Funding; Affimed: Research Funding. Shah:Dren Bio: Consultancy.

e24103 Background: Many of the 200,000 patients diagnosed with breast cancer (BC) annually in the United States receive anthracycline-based therapy, increasing their risk of future congestive heart failure. N-terminal brain natriuretic peptide (NT-proBNP) has been used as a biomarker of asymptomatic cardiac dysfunction in the general population and is of interest to identify patients who might benefit from echocardiography during survivorship. This study aimed to assess how age, baseline comorbidities, and time since BC diagnosis impact NT-proBNP levels after anthracycline-based chemotherapy. Methods: This retrospective study, using samples collected in our ongoing prospective Mayo Clinic Breast Disease Registry, included 20 survivors of non-metastatic BC patients per year for each of the first 5 years after anthracycline-based chemotherapy (n=100 total). NT-pro-BNP levels were assessed using a Roche immunoassay. Cardiac risk factors were obtained by chart review. Multivariable linear regression models assessed associations between NT-proBNP values and these independent variables: baseline cardiac risk factors (including hypertension, hyperlipidemia, obesity, diabetes mellitus, and smoking), tumor ER status (surrogate for possible endocrine therapy), time between diagnosis and serum collection, T and N status, use of trastuzumab, and age. Results: The mean age at the time of BC diagnosis was 52.2 (SD 9.8). 13% of tumors were human epidermal growth factor receptor (HER2)-positive and 71% were estrogen receptor (ER) positive. NT-proBNP was elevated in 34%. Mean NT-BNP level was higher (p=0.047) for those in years 4-5 (158 pg/mL) compared to those in years 1-3 (106 pg/mL) (See Table.) Models revealed years from diagnosis to serum draw (p=0.026), older age (p=0.006), more cardiac risk factors (p=0.064), and N2-3 (p=0.001) were associated with elevated NT-pro-BNP level. Use of trastuzumab, ER status, and tumor size were not associated with NT-proBNP. Conclusions: NT-proBNP is elevated in 1/3 of survivors who received anthracycline therapy for BC. As expected, cardiac risk factors and advancing age are associated with higher NT-proBNP. NT-proBNP values >300 were only found in patients who were 4-5 years after diagnosis. Additional research will be needed to further define the diagnostic and prognostic merit of NT-proBNP in survivors after receipt of anthracycline therapy. [Table: see text]

1044 Background: Trastuzumab is well-demonstrated to be associated with cardiotoxicity (typically reduced ejection fraction), most commonly in patients who also receive anthracycline. The vascular effects of trastuzumab and anthracycline are understudied; we aimed to compare change in endothelial function during and after trastuzumab and to assess how anthracycline receipt affects this. Methods: This is an observational prospective study of women with newly diagnosed HER2-positive breast cancer. All participants underwent baseline evaluation of endothelial function testing by use of the EndoPAT2000 device approximately every three months over the subsequent 18 months after the initiation of HER2-directed therapy +/- anthracycline. The primary endpoint was change in endothelial function over time using the reactive hyperemia index (RHI). Framingham Risk Score (FRS) and lower RHI are both known to be independent predictors of future cardiovascular events in the general population. RHI deterioration was defined as a 20% reduction from baseline RHI to any available follow-up RHI assessment. Univariate analyses assessed if age, FRS, baseline RHI, and RHI deterioration differed between recipients and non-recipients of anthracycline using the Wilcoxon test. A multivariate logistic model evaluated FRS, age, and anthracycline receipt as possible independent predictors of RHI deterioration. Results: Among 38 eligible patients who consented and completed baseline assessments in addition to at least one follow-up assessment, 17 (45%) subsequently received anthracycline. 145 total follow-up RHI assessments were available overall (5 per patient on average). There were no differences between recipients and non-recipients of anthracyclines with regard to age [mean 49 years (SD 12) vs 53 years (SD 11); p=0.25], baseline FRS [mean 1.0 (SD 1.0) vs 1.5 (SD 1.4); p= 0.28] or baseline RHI [mean 2.4 (SD 0.6) vs 2.1 (SD 0.7); p=0.09]. RHI deterioration was more common for anthracycline recipients (mean 43% vs 21%; p=0.004), and in the multivariate model, anthracycline use was the only independent predictor of RHI deterioration (odds ratio: 2.8; 95% confidence interval: 1.35-6.07; p=0.006). Conclusions: This study suggests that endothelial dysfunction is more common after combined anthracycline and HER2-directed therapy than after HER2-directed therapy alone. RHI should be further studied as a possible early biomarker of cardiovascular toxicity in patients receiving treatment for breast cancer.