Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm with high morbidity and mortality. The initiating mechanism during the pathogenesis of KHE has yet to be discovered. The main pathological features of KHE are abnormal angiogenesis and lymphangiogenesis. KHEs are clinically heterogeneous and may develop into a lifethreatening thrombocytopenia and consumptive coagulopathy, known as the Kasabach-Merritt phenomenon (KMP). The heterogeneity and the highly frequent occurrence of disease-related comorbidities make the management of KHE challenging. Currently, there are no medications approved by the FDA for the treatment of KHE. Multiple treatment regimens have been used with varying success, and new clinical trials are in progress. In severe patients, multiple agents with variable adjuvant therapies are given in sequence or in combination. Recent studies have demonstrated a satisfactory efficacy of sirolimus, an inhibitor of mammalian target of rapamycin, in the treatment of KHE. Novel targeted treatments based on a better understanding of the pathogenesis of KHE are needed to maximize patient outcomes and quality of life. This review summarizes the epidemiology, etiology, pathophysiology, clinical features, diagnosis and treatments of KHE. Recent new concepts and future perspectives for KHE will also be discussed.

Kaposiform hemangioendothelioma (KHE) is an aggressive disease with high morbidity and mortality. The aim of this study was to retrospectively evaluate the efficacy and safety of sirolimus for the treatment of progressive KHE. A multicenter, retrospective cohort study was conducted in patients with progressive KHE treated with sirolimus. A total of 52 patients were analyzed. Thirty-seven (71%) patients exhibited Kasabach-Merritt phenomenon (KMP) and were significantly younger than the patients without KMP [95% confidence interval (CI), 14.39-41.61; p < 0.001]. Patients without KMP were all treated with sirolimus alone, whereas 21 KMP patients with severe symptoms received short-term combination therapy with prednisolone. Overall, 96% and 98% of patients showed improved relief of notable symptoms and/or improved complications at 6 and 12 months after treatment, respectively. After sirolimus treatment, significant decreases in mean severity scores occurred at 6 months (95% CI, 2.23-2.54, p < 0.001) and 12 months (95% CI, 1.53-1.90, p < 0.001). Compared to KMP patients, patients without KMP showed a response that was similar to but less pronounced during the 12 months of treatment (95% CI, 40.87-53.80; p < 0.001). For subgroup analysis of KMP patients, there were no significant differences in tumor shrinkage between those treated with combination therapy and those receiving sirolimus alone (95% CI, 18.11-25.02; p > 0.05). No patients permanently discontinued treatment due to toxicity-related events, and no drug-related deaths occurred. Sirolimus was effective and safe for the treatment of progressive KHE. Sirolimus may be considered as a first-line therapy or as part of a multidisciplinary approach for the treatment of KHE.

Most KHEs appeared before 12 months of age. KHEs are associated with various major complications, which can occur in combination and develop early in the disease process. Young age, large lesion size and mixed lesion type are important predictors of KMP.

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Currently, propranolol is the most preferred systemic therapy for problematic infantile hemangiomas (IHs). However, the side effects such as bronchial hyperreactivity may be intolerable. The aim of this study was to evaluate the frequency, risk factors and management of intolerable side effects (ISEs) during propranolol therapy. In total, 1260 children were studied. The incidence of ISEs was 2.1% (26 patients). Severe sleep disturbance was the most common reason for propranolol cessation, accounting for 65.4% of cases. In total, 23 and 3 patients received atenolol and prednisolone as second-line therapy, respectively. Treatment response was observed in 92.3% (24/26) of cases (showing excellent or good response to therapy). No toxicity-related permanent treatment discontinuation occurred during atenolol or prednisolone therapy. In the univariate analysis, younger age, premature birth, and lower body weight were associated with ISEs (P < 0.05). In the multivariate analysis, only age (95% confidence interval [CI]: 1.201–2.793, P = 0.009) and body weight (95% CI: 1.036–1.972, P = 0.014) were associated with ISEs. Our study suggests that ISEs are rare in patients with IHs who are treated with propranolol. Predictive factors for ISEs include younger age and lower body weight. Atenolol and prednisolone are effective and safe alternatives to propranolol in the treatment of refractory IHs.

IMPORTANCEPropranolol has become the first-line therapy for problematic infantile hemangiomas (IHs) that require systemic therapy. However, different adverse events have been reported during propranolol treatment. The positive efficacy and safety of atenolol raise the question of whether it could be used as a promising therapy for IH.OBJECTIVE To compare the efficacy and safety of propranolol vs atenolol in infants (between age 5 and 20 weeks) with problematic IHs who required systemic therapy. DESIGN, SETTING, AND PARTICIPANTS This was a prospective, multicenter, randomized, controlled, open-label clinical trial conducted in collaboration among 6 separate investigation sites in China from February 1, 2015, to December 31, 2018. A total of 377 patients met the criteria for inclusion and were randomized to the propranolol (190 [50.4%]) and atenolol (187 [49.6%]) groups. Data were analyzed in June 2020.INTERVENTIONS Participants were randomized to receive either propranolol or atenolol for at least 6 months. They completed efficacy assessments at 2 years after the initial treatment. MAIN OUTCOMES AND MEASURESThe primary outcome was any response or nonresponse at 6 months. The key secondary outcome was changes in the hemangioma activity score. RESULTSOf 377 participants, 287 (76.1%) were female, and the mean (SD) age was 10.2 (4.0) weeks in the propranolol group and 9.8 (4.1) weeks in the atenolol group. After 6 months of treatment, in the propranolol and atenolol groups, the overall response rates were 93.7% and 92.5%, respectively (difference, 1.2%; 95% CI, −4.1% to 6.6%). At 1 and 4 weeks after treatment, and thereafter, the hemangioma activity score in the atenolol group aligned with the propranolol group (odds ratio, 1.034; 95% CI, 0.886-1.206). No differences between the propranolol group and atenolol group were observed in successful initial responses, quality of life scores, complete ulceration healing times, or the rebound rate. Both groups presented a similar percentage of complete/nearly complete responses at 2 years (82.1% vs 79.7%; difference, 2.4%; 95% CI, −5.9% to 10.7%). Adverse events were more common in the propranolol group (70.0% vs 44.4%; difference, 25.6%; 95% CI, 15.7%-34.8%), but the frequency of severe adverse events did not differ meaningfully between the groups. CONCLUSIONS AND RELEVANCEIn this randomized clinical trial, when compared with propranolol, atenolol had similar efficacy and fewer adverse events in the treatment of infants with problematic IHs. The results suggest that oral atenolol can be used as an alternative treatment option for patients with IH who require systemic therapy.

The Kasabach-Merritt phenomenon (KMP) in kaposiform hemangioendothelioma (KHE) is characterized by life-threatening thrombocytopenia and consumptive coagulopathy. This study compared the efficacy and safety of sirolimus plus prednisolone versus sirolimus monotherapy as treatment strategies for KHE with KMP in the largest cohort to date. Participants were randomized to receive either sirolimus in combination with a short course of prednisolone or sirolimus monotherapy for at least 12 months. The primary outcome was defined as achievement of a durable platelet response (platelet count &gt;100×109/L) at week 4. Participants completed efficacy assessments 2 years after the initial treatment. At week 4, a durable platelet response was achieved by 35 of 37 patients given sirolimus and prednisolone compared with 24 of 36 patients given sirolimus monotherapy (difference 27.9%; 95% CI, 10.0% to 44.7%). Compared with the sirolimus monotherapy group, the combination treatment group showed improvements in terms of measures of durable platelet responses at all points during the initial 3-week treatment period, median platelet counts during weeks 1 to 4, increased numbers of patients achieving fibrinogen stabilization at week 4, and objective lesion responses at month 12. Patients receiving combination therapy had fewer blood transfusions and a lower total incidence of disease sequelae than patients receiving sirolimus alone. The frequencies of total adverse events and grade 3-4 adverse events during treatment were similar in both groups. The responses seen in patients with KHE with KMP were profound and encouraging, suggesting that sirolimus plus prednisolone should be considered a valid treatment for KHE with KMP. ClinicalTrial.gov, number NCT03188068

Aim Kaposiform haemangioendothelioma (KHE) is a rare, potentially life‐threatening vascular tumour that is often associated with thrombocytopenia and coagulopathy, known as the Kasabach‐Merritt phenomenon (KMP). Because of the rarity and complexity of KHE, the optimal paradigm for treating KHE has yet to be elucidated. We aim to assess the efficacy and safety of vincristine and sirolimus for the treatment of KHE. Methods A comprehensive review of the literature was conducted from January 1993 to June 2018. A total of 15 studies were selected for the meta‐analysis. Five studies included 75 individuals and reported the response and side effects to vincristine in the treatment of KHE with or without KMP. A total of 10 studies that included 127 individuals reported the response and safety of sirolimus for treating KHE with or without KMP. Results The pooled odds ratio (OR) for the effectiveness of vincristine was 0.72. The pooled OR for the effectiveness of sirolimus was 0.91. The side effects associated with vincristine during the treatment included neuropathy, abdominal pain, loss of appetite and mild elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The side effects associated with sirolimus therapy included bronchitis; lymphopenia; elevated AST, ALT and platelets; hyperlipidaemia; opportunistic infection; mild reversible leukopenia; mucositis; fever; pain and skin rash/vomiting and diarrhoea. Conclusions This systematic review showed a high efficacy of vincristine and sirolimus in the treatment of KHE. Based on the available data in the literature, it appears that sirolimus is potentially an efficacious and safe treatment option for KHE. Further randomised, controlled trials are recommended.