Kaposiform hemangioendothelioma without Kasabach-Merritt phenomenon

Vascular tumors of intermediate malignancy: An update

The term "hemangioendothelioma" is used for endothelial neoplasms of intermediate malignancy and describes a group of rare neoplasms having biologic behavior falling in between that of the benign hemangiomas and fully malignant angiosarcomas. The hemangioendotheliomas fall into several specific, clinicopathologically and genetically distinct entities, specifically epithelioid hemangioendothelioma, kaposiform hemangioendothelioma, papillary intralymphatic angioendothelioma and retiform hemangioendothelioma (hobnailed hemangioendothelioma), pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, and YAP1::TFE3-fused hemangioendothelioma. The clinical, morphologic, immunohistochemical, and genetic features, and the differential diagnosis of each of these rare entities are discussed in this review.

Construction and applications of the EOMA spheroid model of Kaposiform hemangioendothelioma

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare intermediate vascular tumor with unclear pathogenesis. Recently, three dimensional (3D) cell spheroids and organoids have played an indispensable role in the study of many diseases, such as infantile hemangioma and non-involuting congenital hemangiomas. However, few research on KHE are based on the 3D model. This study aims to evaluate the 3D superiority, the similarity with KHE and the ability of drug evaluation of EOMA spheroids as an in vitro 3D KHE model.

RESULTS

After two days, relatively uniform morphology and high viability of EOMA spheroids were generated by the rotating cell culture system (RCCS). Through transcriptome analysis, compared with 2D EOMA cells, focal adhesion-related genes such as Itgb4, Flt1, VEGFC, TNXB, LAMA3, VWF, and VEGFD were upregulated in EOMA spheroids. Meanwhile, the EOMA spheroids injected into the subcutaneous showed more obvious KMP than 2D EOMA cells. Furthermore, EOMA spheroids possessed the similar characteristics to the KHE tissues and subcutaneous tumors, such as diagnostic markers (CD31 and LYVE-1), cell proliferation (Ki67), hypoxia (HIF-1α) and cell adhesion (E-cadherin and N-cadherin). Based on the EOMA spheroid model, we discovered that sirolimus, the first-line drug for treating KHE, could inhibit EOMA cell proliferation and downregulate the VEGFC expression. Through the extra addition of VEGFC, the effect of sirolimus on EOMA spheroid could be weakened.

CONCLUSION

With a high degree of similarity of the KHE, 3D EOMA spheroids generated by the RCCS can be used as a in vitro model for basic researches of KHE, generating subcutaneous tumors and drug screening.

Treatment practices and response in kaposiform hemangioendothelioma: A multicenter cohort study

BACKGROUND AND OBJECTIVES

Kaposiform hemangioendothelioma (KHE) and tufted angioma (TA) are rare vascular tumors in children historically associated with significant morbidity and mortality. This study was conducted to determine first-line therapy in the absence of available prospective clinical trials.

METHODS

Patients from 17 institutions diagnosed with KHE/TA between 2005 and 2020 with more than 6 months of follow-up were included. Response rates to sirolimus and vincristine were compared at 3 and 6 months. Durability of response and response to other treatment modalities were also evaluated.

RESULTS

Of 159 unique KHE/TA subjects, Kasabach-Merritt phenomenon (KMP) was present in 64 (40.3%), and only two patients were deceased (1.3%). Over 60% (n = 96) demonstrated treatment response at 3 months, and more than 70% (n = 114) by 6 months (no significant difference across groups). The vincristine group had higher radiologic response at 3 months compared to sirolimus (72.7% vs. 20%, p = .03), but there were no differences between these groups at 6 months. There were no differences in rates of recurrent or progressive disease between vincristine and sirolimus.

CONCLUSIONS

In this large, multicenter cohort of 159 patients with KHE/TA, rates of KMP were consistent with historical literature, but the mortality rate (1.3%) was much lower. Overall treatment response rates were high (>70%), and there was no significant difference in treatment response or durability of disease comparing sirolimus to vincristine. Our results support individualized treatment decision plans depending on clinical scenario and patient/physician preferences. Response criteria and response rates reported here will be useful for guiding future treatment protocols for vascular tumors.

Cutaneous vascular tumors: an updated review

Cutaneous vascular tumors constitute a heterogeneous group of entities that share overlapping morphologic and immunohistochemical features, which can be diagnostically challenging for pathologists and dermatopathologists. Our understanding and knowledge of vascular neoplasms have improved over time, resulting in both a refinement of their classification by the International Society for the Study of Vascular Anomalies (ISSVA) and an improvement in the accurate diagnosis and clinical management of vascular neoplasms. This review article aims to summarize the updated clinical, histopathological, and immunohistochemical characteristics of cutaneous vascular tumors, as well as to highlight their associated genetic mutations. Such entities include infantile hemangioma, congenital hemangioma, tufted angioma, spindle cell hemangioma, epithelioid hemangioma, pyogenic granuloma, Kaposiform hemangioendothelioma, retiform hemangioendothelioma, pseudomyogenic hemangioendothelioma, Kaposi sarcoma, angiosarcoma, and epithelioid hemangioendothelioma.

Impact of age and tumor size on the development of the Kasabach-Merritt phenomenon in patients with kaposiform hemangioendothelioma: a retrospective cohort study

Introduction

The Kasabach-Merritt phenomenon (KMP) is a severe complication of kaposiform hemangioendothelioma (KHE). The risk factors for KMP need further investigation.

Methods

The medical records of patients with KHE were reviewed. Univariate and multivariate logistic regression models were used for the risk factors for KMP, and the area under the receiver operator characteristic (ROC) curve was used to assess the predictive power of risk factors.

Results

A total of 338 patients with KHE were enrolled. The incidence of KMP was 45.9%. Age of onset (P < 0.001, odds ratio [OR] 0.939; 95% confidence interval [CI] 0.914-0.966), lesion size (P < 0.001, OR 1.944; 95% CI 1.646-2.296), mixed type (P = 0.030, OR 2.428; 95% CI 1.092-5.397), deep type (P = 0.010, OR 4.006; 95% CI 1.389-11.556), and mediastinal or retroperitoneal lesion location (P = 0.019, OR 11.864; 95% CI 1.497-94.003) were correlated with KMP occurrence through multivariate logistic regression. ROC curve analysis revealed that the optimal cutoffs were 4.75 months for the age of onset (P < 0.001, OR 7.206, 95% CI 4.073-12.749) and a lesion diameter of 5.35 cm (P < 0.001, OR 11.817, 95% CI 7.084-19.714). Bounded by a lesion size of 5.35 cm, we found significant differences in tumor morphology, age of onset, treatments, and hematological parameters. Using an onset age of 4.75 months as a cutoff, we found significant differences in tumor morphology, lesion size, hematological parameters, and prognosis.

Conclusion

For KHE patients with an onset age <4.75 months and/or lesion diameter >5.35 cm, clinicians should be wary of the occurrence of KMP. Active management is recommended to improve the prognosis.

Kaposiform Haemangioendothelioma of the Sublingual Gland in an Adult

Kaposiform haemangioendotheliomas (KHE) are extremely rare, borderline malignant, locally aggressive vascular tumours. KHE is usually found in the retroperitoneum, over the extremities, the soft tissues of the trunk, mediastinum and the head and neck regions. We present a very rare case of KHE of the sublingual gland in an adult, which was not associated with Kasabach-Merritt phenomenon and was resected completely without any recurrence. To the best of our knowledge, this is the first reported case in the literature of a KHE arising from the salivary glands in an adult.

Multivertebral Kaposiform hemangioendothelioma presenting as scoliosis - A case report and review of literature

Kaposiform hemangioendothelioma (KHE) is a rare, locally invasive vascular tumour of childhood that may occur in soft tissue or bones, and is associated with cutaneous plaques and Kasabach-Merritt phenomenon (KMP). We present an instance of a 9-year-old girl with primary vertebral involvement of KHE, whose clinical presentation was with painless, progressive scoliosis alone, sans cutaneous markers. We highlight the imaging features of this rare manifestation and importance of histopathological diagnosis for optimal management.

How we approach coagulopathy with vascular anomalies

Some vascular anomalies can present with challenging hematologic aberrations. Kaposiform hemangioendothelioma (KHE) may be complicated with Kasabach-Merritt phenomenon (KMP) and stagnant blood flow in slow-flow malformations can promote activation and consumption of coagulation factors, which results in bleeding and clotting known as localized intravascular coagulopathy (LIC). These patients can experience significant morbidity secondary to pain due to thrombosis and are at higher risk of hematologic complications during surgical procedures. No standard of care has been established to prevent or manage these complications. This review focuses on the management of coagulopathy in children and adults with vascular anomalies.

MRI-based radiomics in distinguishing Kaposiform hemangioendothelioma (KHE) and fibro-adipose vascular anomaly (FAVA) in extremities: A preliminary retrospective study

OBJECTIVE

To investigate the pretreatment differentiation between Kaposiform hemangioendothelioma (KHE) and fibro-adipose vascular anomaly (FAVA) in extremities of pediatric patients. To build and validate an MRI-based radiomic model.

METHOD

In this retrospective study, we obtained imaging data from 43 patients. We collected and compared clinical information, sketched region of interest (ROI), and extracted radiomic features from fat-suppressed T2-weighted (T2FS) images of the two cohorts of 30 and 13 patients respectively (training versus testing cohort 7:3). To select features, we used two sample t-test and the least absolute shrinkage and selection operator (LASSO) regression. The support vector machine (SVM) classification was constructed and evaluated by receiver operating characteristic (ROC) analysis.

RESULTS

Thirty patients with KHE and 13 patients with FAVA in the extremities were included. Most lesions demonstrated low to intermediate signal intensity on T1-weighted images and hyperintense signals on T2-weighted ones. They also showed similar traits pathologically. Initially, 107 radiomic features were acquired and then three were finally selected. The support vector machine (SVM) model was able to differentiate the two anomalies from each other with an area under the curve (AUC) of 0.807 (95%CI 0.602-1.000) and 0.846 (95%CI 0.659-1.000) in training and testing cohort, respectively.

CONCLUSION

The derived radiomic features were helpful in differentiating KHE from FAVA. A model which contained these features might further improve the performance and hopefully could serve as a potential tool for identification.

Malignant Superficial Mesenchymal Tumors in Children

Malignant superficial mesenchymal tumors are a very diverse group of neoplasms with few clinical and radiological discriminatory factors. Hence, some of these cancers are rarely suspected based on clinical and radiological grounds, others may be easily misdiagnosed, and the histological analysis of a biopsy or resection is central in the diagnostic process. In children, the age at presentation is a major element of the differential diagnosis. Some tumors have a very distinct epidemiology, while others may be seen at any age. More recently, the advances in molecular biology have greatly improved the diagnosis of mesenchymal tumors and new entities are still being described. In the present review, we provide an overview of the diversity of malignant superficial mesenchymal tumors in children, including new and/or rare entities. We discuss the important diagnostic features, be they clinical, histological, or molecular. Special attention was given to the genetic features of these tumors, particularly when they were helpful for the diagnosis or treatment.

Case Report: Congenital Intracranial Kaposiform Hemangioendothelioma Treated With Surgical Resection

Background

Kaposiform hemangioendothelioma (KHE) is a locally aggressive but non-metastatic vascular neoplasm. Most studies have been restricted to small case series of limited generalizability. Intracranial KHE is extremely rare with only three cases reported in the literature. Here, we report a case of congenital intracranial KHE who underwent surgical resection, and no lesion recurrence was seen during the follow-up period of 13 months.

Case Description

A 2-month-old boy initially presented with a left temporal mass following birth. Antenatal ultrasound at 36 weeks of gestation demonstrated a hyperechoic signal present in the left frontal lobe, with clear borders and irregular morphology. There were neither cutaneous abnormalities nor other neurologic examination abnormalities. No laboratory abnormality was identified. Computed tomography (CT) scans suggested that a massive hematoma was noted under the left frontal skull plate, with a little subdural hemorrhage in the adjacent temporal area. The adjacent meninges enhanced and thickened on contrasted T1 magnetic resonance (MR). After the multidisciplinary diagnostic assessment, the surgery was performed by the left frontotemporal craniotomy approach. The operation was extremely difficult. We completely removed the tumor, and the involved dura and brain tissue were resected with the lesion in a piecemeal fashion. On postoperative-day (POD) 3 and POD 14, the head CT re-examination revealed that cerebral perfusion improved gradually. The MRI of 6- and 12-month after operation showed no local recurrence or metastasis.

Conclusions

Intracranial KHE is difficult to diagnose early and the prognosis has been uniformly poor. We supposed that meticulous intraoperative hemostasis is the key for a successful operation, and the radical resection of the tumor and involved structures are essential to reduce recurrence.

Neonatal vascular anomalies manifesting as soft-tissue masses

The broad and heterogeneous spectrum of vascular anomalies ranges from an innocuous localized cutaneous discoloration to complex, extensive and life-threatening diagnoses. While many of these lesions are present at birth, smaller and deeper lesions might be clinically occult for months or years. Certain vascular anomalies commonly manifest in the prenatal or neonatal period and often have suggestive clinical and imaging features that can aid the radiologist in making a correct diagnosis. The characteristics of such lesions presenting very early in life, particularly those manifesting as soft-tissue masses, are the focus of this review.

Primary Kaposiform Hemangioendothelioma of the Humerus: A Case Report

Kaposiform hemangioendothelioma (KHE) is a neoplasm originating mainly from vessels and has a mild proclivity for malignancy. This neoplasm mainly involves somatic soft tissue and retroperitoneum. Histological findings include a nodular arrangement of oval-to-spindle cells containing pale cytoplasm. Vascular spaces are in the form of slit-like channels in which red blood cells are evident. Here, we report the case of a two-year-old male who presented with Erb’s palsy and a mass lesion in the right humerus. Tissue biopsy features were compatible with KHE.

Comprehensive Therapy for Infant Vascular Tumor Associated With Kasabach-Merritt Phenomenon-Single-Center Primary Experience

OBJECTIVE

To introduce our single-center experience of infant vascular tumor associated with Kasabach-Merritt phenomenon (KMP) which received combined medicine treatment with intralesional laser photocoagulation (ILP) and sclerotherapy.

METHODS

A retrospective study was conducted using medical records of all children with a diagnosis of kaposiform hemangioendothelioma (KHE) or tufted angioma (TA) associated with KMP treated with medicine, intralesional laser photocoagulation (ILP), and sclerotherapy between February 2017 and November 2020. Clinical features, response to comprehensive therapy, and outcomes were recorded.

RESULTS

A total of 23 patients including nine females (39%) and 14 males (61%) were identified. The mean age was 6.9 months (age range, 11 days-2 years) at the time of treatment. Nine children (39%) demonstrated sensitivity to single corticosteroid therapy; 14 children (61%) received combined therapy with intravenous Vincristine (VCR) and corticosteroid therapy. All children had at least two ILP and sclerotherapy performed, with a mean of 3.5 procedures (range: 2-6). Of these 14 children, only one experienced a relapse of thrombocytopenia and the remaining 13 children had no clinical symptoms recurred.

CONCLUSION

The combined therapy modalities could induce a more rapid tumor response and resolution of KMP and decrease the rebound rates. This research presents a novel and safe multi-modality treatment for infant vascular tumors associated with KMP.

Standards of care for Kasabach-Merritt phenomenon in China

Kasabach-Merritt phenomenon (KMP) is a rare disease that is characterized by severe thrombocytopenia and consumptive coagulation dysfunction caused by kaposiform hemangioendothelioma or tufted hemangioma. This condition primarily occurs in infants and young children, usually with acute onset and rapid progression. This review article introduced standardized recommendations for the pathogenesis, clinical manifestation, diagnostic methods and treatment process of KMP in China, which can be used as a reference for clinical practice.

Kaposiform Hemangioendothelioma: clinicopathological characteristics of 8 cases of a rare vascular tumor and review of literature

BACKGROUND

Kaposiform Hemangioendothelioma (KHE) is a rare vascular tumor of intermediate malignant potential which shows locally aggressive growth but only rarely metastasizes. It is mostly considered to be a tumor of pediatric population but its occurrence in the adults is not uncommon as once considered. Histologically, KHE can mimic other soft tissue neoplasms of different behaviors (e.g. Kaposi Sarcoma, hemangioma) and establishing the correct diagnosis is important for appropriate treatment. Herein, we describe the clinicopathological features of 8 cases of KHE which will be helpful in making their diagnosis.

METHODS

We reviewed pathology reports, microscopy glass slides and obtained follow up information about 8 cases of KHE which were diagnosed at our institution from January 2008 till June 2020. Immunohistochemical stain for HHV8 was also performed.

RESULTS

Age ranged from 7 months to 25 years. Seven patients were less than 20 years of age and one patient was 25 years old. Equal gender distribution was observed. Extremities were the most common sites of involvement, followed by head and neck, pancreas and ischiorectal region. 2 cases were resection specimen and all others were incisional biopsies. The largest tumor size was 5.5 cm in one of the resections. The incisional/fragmented tissues were all less than 5 cm in aggregate. Most cases showed predominance of nodular growth and a minor component of spindle cell population along with lymphangiomatosis like vascular channels, with evidence of microthrombi in 2 cases. Few multinucleated giant cells were observed in 2 cases. None of the cases exhibited significant nuclear atypia or mitotic activity. One of the cases arising in dermis showed underlying bone involvement. HHV8 was negative in 7/7 cases.

CONCLUSIONS

KHE can also involve adult population and it should always be considered in the differential diagnoses of a vascular lesion. Presence of multinucleated giant cells is a rare finding. Knowledge about histological features and potential mimics is helpful in avoiding misdiagnosis.

Kaposiform haemangioendothelioma: magnetic resonance imaging features in 64 cases

Background

Kaposiform haemangioendothelioma (KHE) is a rare, locally aggressive disorder. The presenting and imaging features of KHE can overlap with other vascular anomalies and tumours. We aimed to analyse the imaging findings of KHE disorder and highlight features most suggestive of this diagnosis.

Methods

The clinical features and imaging findings were retrospectively reviewed in 64 patients with pathological diagnosis of KHE.

Results

Of the 64 patients diagnosed with KHE, 36 patients were < 6 months and 28 patients were ≥ 6 months. The most common presenting features were Kasabach-Merritt phenomenon (KMP, 42.2 %), visible cutaneous lesions (90.6 %), oedema or swelling (43.8 %) and destructive changes or remodelling of adjacent bone (42.2 %). Compared with patients in the group ≥ 6 months, patients in the group < 6 months have higher odds of KMP (P = 0.000), infiltrative lesion with ill-defined borders (P = 0.044). The group ≥ 6 months have higher odds of destructive changes or remodelling of adjacent bone (P = 0.002). In all patients, the lesions in all of the 64 patients were hypointense or isointense compared with muscle on T1-weighted sequences, and hyperintense on T2-weighted or inversion-recovery sequences, nine patients (14.1 %) showed vascularity. There were 28 patients (43.8 %) with characteristic enhancing and infiltrative soft-tissue thickening.

Conclusions

Presence of visible cutaneous lesions with ill-defined borders, destructive changes or remodelling of adjacent bone, severe thrombocytopenia and consumptive coagulopathy should favour the diagnosis of KHE.

Comparison of efficacy and safety of corticosteroid and vincristine in treating kaposiform hemangioendothelioma and tufted angioma: A multicenter prospective randomized controlled clinical trial

Kaposiform haemangioendothelioma (KHE) and tufted angioma (TA) are rare vascular tumors that can cause life-threatening Kasabach-Merritt phenomenon. No evidence-based treatment strategies have yet been established, and its management is still a challenge. The purpose of this multicenter prospective randomized controlled study was to evaluate and compare the efficacy of corticosteroid and vincristine (VCR) in the treatment of KHE and TA. All patients with KHE/TA who met the diagnostic criteria were consecutively recruited. The patients were randomized into a methylprednisolone (MP) group and a VCR group. The primary outcome was the single main parameter effective rate and overall effective rate of corticosteroid and VCR over 1 month after treatment. The single main parameters included platelets, fibrinogen, tumor size, texture, and appearance. From May 2016 to April 2018, a total of 59 patients completed the clinical trial, including 29 in the MP group and 30 in the VCR group. The results showed that VCR was superior to corticosteroid in the improvement of platelet (80.0% vs 44.0%, P = 0.019) and tumor texture (68.9% vs 30.8%, P = 0.007). Although the efficacy of VCR on fibrinogen (23.3% vs 20.7%, P = 1.000), tumor size (23.3% vs 13.8%, P = 0.273), and appearance (65.5% vs 46.2%, P = 0.120) was higher than that of corticosteroid, there was no significant difference (P > 0.05). Meanwhile, the overall effective rate of VCR was higher than that of corticosteroid (56.7% vs 31.0%), but the difference was also not statistically significant (P = 0.067). In conclusion, the therapeutic effect of VCR was significantly better than that of corticosteroid with regard to treating thrombocytopenia and tumor texture. We recommend that VCR could be an option for first-line treatment in KHE/TA patients.

Vascular anomalies: Classification and management

Vascular anomalies are broadly classified into two major categories: vascular tumors and vascular malformations. Most vascular anomalies are caused by sporadic mosaic gene mutations, and recent genetic studies have advanced our understanding of the molecular pathways involved in their pathogenesis. These findings have suggested new therapeutic approaches to vascular anomalies, focusing on their pathogenetic mechanism. This chapter seeks to integrate an improved molecular understanding within the updated classification system of the International Society for Study of Vascular Anomalies. We emphasize the genetic, radiologic, and interventional aspects of diagnosis and management in hopes of allowing improved multidisciplinary collaboration surrounding these complex and interesting anomalies.

A case report of Kaposiform haemangioendothelioma; response with propranolol and steroids

Background

Kaposiform haemangioendothelioma is a rare vascular tumor and may involve skin, deep soft tissue or bone. It is a locally aggressive tumor usually seen in infants. Here we report a case of kaposiform hemagioendothelioma in a child who responded to propranolol and steroids.

Case presentation

A 3-year-old male child presented with a swelling below his right knee with characteristic violet skin lesion. There was no evidence of Kasabach–Merritt phenomenon. After no improvement with several attempts at debridement and anti-tubercular treatment; a diagnosis of Kaposiform Haemangioendothelioma was reached on the basis of overall clinical picture and histology. The child was treated with propranolol and steroids and had an excellent clinical response and a near complete resolution on imaging at 5 months.

Conclusions

These cases are often misdiagnosed and despite a delay in diagnosis have good outcomes with appropriate multimodality management. This case highlights the unique and typical characteristics of kaposiform haemangioendothelioma.

Kaposiform Hemangioendothelioma in the Thoracic Spine: A Case Report and Review of the Literature

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor of childhood. It has been most commonly reported in the trunk, retroperitoneum, and extremities, but cases involving the head and neck have been described. While thought to have limited metastatic potential, it is associated with Kasabach-Merritt syndrome (KMS), a consumptive coagulopathy and profound thrombocytopenia that is associated with significant mortality. Twelve cases of KHE with bony involvement have previously been reported. Of these, only 2 involved the spine, and both were managed with medical therapy alone.

CASE PRESENTATION

We report the first case of spinal KHE causing spinal cord compression managed with surgical excision presented in the literature to date.

CONCLUSIONS

There are a number of treatment modalities outlined in the literature. The lack of a consensus is due to the varying methods of presentation, difficulty in diagnosis, and disease rarity. Our case highlights the potential speed of local growth of this tumor, meaning that excision may be a technical challenge, especially when there is epidural extension. Treating clinicians should be aware of the risk of progression beyond the initial tumor boundaries to involve new vertebrae.

Kaposiform hemangioendothelioma: current knowledge and future perspectives

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 life-threatening 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.

Bifocal Tibial Kaposiform Hemangioendothelioma Responsive to Vincristine Therapy: A Case Report

BACKGROUND Kaposiform hemangioendothelioma is a rare locally aggressive vascular endothelial-derived spindle cells neoplasm. Herein, we report a rare case of bifocal tibial kaposiform hemangioendothelioma. CASE REPORT A 9-year-old female presented with a 2-year history of pain and swelling in the left leg. The patient had a high plasma level of the D-dimer and fibrinogen. Radiography revealed a centric lytic lesion on the left proximal tibial metaphysis and an eccentric lateral distal tibial metaphyseal. Histopathologic examination of the sample taken from the distal tibia revealed a dense spindle cell tumor with lobular architecture composed of compact spindle cells compressing small slit-like vascular spaces, forming glomeruloid nests. No necrosis was identified. Based on these findings and the positive immunohistochemical staining for CD31, CD34, and D2-40, the patient was diagnosed with kaposiform hemangioendothelioma. Treatment was started by using vincristine chemotherapy, after which the patient developed temporary peroneal neuropathy, which improved over the next 3 months. CONCLUSIONS Bifocal tibial kaposiform hemangioendothelioma lesions are unique in pediatric patients and can be successfully treated with vincristine chemotherapy. In these cases, the treating physician should be aware of peroneal neuropathy as a potential complication of vincristine administration.

Ultrasonography and magnetic resonance imaging features of kaposiform hemangioendothelioma and tufted angioma

Kaposiform hemangioendothelioma (KHE) and tufted angioma (TA) primarily occurring in infants are difficult to distinguish. This study evaluated ultrasonography (US) and magnetic resonance imaging (MRI) features of KHE and TA. Pathologically proven TA (n = 21) and KHE (n = 40 [11 KHE + Kasabach-Merritt phenomenon [KMP]]) occurring between January 2015 and December 2017 were reviewed. US (n = 61) and MRI (n = 50) findings were retrospectively evaluated. On US, KHE and TA lesions were subcutaneous, while 40% of KHE exhibited an infiltrative pattern extending into adjacent muscles. Of TA lesions, 42.9% were hyperechoic and 96.15% of KHE lesions exhibited mixed echogenicity. Of TA lesions, 76.2% exhibited well-defined margins and all KHE lesions exhibited ill-defined margins. The depth and vascular density of KHE and KHE + KMP were significantly increased compared with TA. The arterial peak systolic blood flow velocity of KHE + KMP was significantly higher than that in TA and KHE. KHE and KHE + KMP were significantly harder than TA on elastography. 3-D color Doppler revealed branch-shape blood flow for KHE and KHE + KMP lesions; for TA, it revealed a dot-like and striped pattern. Considering MRI findings, KHE and KHE + KMP were more likely to exhibit diffuse heterogeneous enhancement after contrast than TA. KHE was infiltrative and more likely to be thick, hypoechoic, ill-defined, richly vascular and hard than TA on US. KHE lesions were subcutaneous and reticular, with heterogeneous enhancement on MRI. Awareness of these features should prompt radiologists in the differential diagnosis of pediatric masses.

Abnormal hemostasis in children with vascular anomalies, part I: Thrombocytopenias among different vascular anomalies

Long before the classification of vascular anomalies from the International Society for the Study of Vascular Anomalies (ISSVA) provided a framework to differentiate vascular anomalies, otherwise known as vascular birthmarks, it was recognized that patients with such lesions can present with acute life-threatening hemostatic and/or thrombotic complications, as well as chronic long-standing bleeding or thrombotic issues. Scenarios such as a rapidly growing vascular lesion with severe acute thrombocytopenia, a visceral hemorrhagic lesion, a lesion associated with repetitive and painful superficial thrombosis, and cases of unprovoked or post-procedural fatal pulmonary embolism highlight the wide spectrum of manifestations of abnormal coagulation in patients with vascular anomalies. The separation of vascular anomalies into two distinct groups, vascular tumors and vascular malformations, was followed by the characterization that their respective coagulopathies were due to either a derangement of platelets or to a disequilibrium of the patient's coagulation/fibrinolytic process. This configuration of coagulopathies will be the foundation for this two-chapter review series. In the initial review, coagulopathies where thrombocytopenia is the main feature will be characterized, whereas the second review will focus on vascular malformations that have a coagulation disorder secondary to some degree of coagulation consumption and/or fibrinolytic pathway derangement.

Vascular anomalies of the upper limb

Vascular anomalies are common in the upper extremities, but there continues to be a relative paucity of information about them in publications dealing with surgery in the hands and upper limbs. The wide spectrum of pathology and an inconsistent use of terminology make vascular anomalies susceptible to incorrect diagnosis and as a result, to misdirected management. This article aims to provide an update on vascular anomalies relevant to the upper limbs, focusing on significant advances in pathogenesis and genetics, classification systems, diagnosis and treatment.

Local suture ligation-assisted percutaneous sclerotherapy for Kasabach-Merritt phenomenon-associated kaposiform haemangioendothelioma

Kaposiform haemangioendotheliomas (KHEs) complicated by the Kasabach-Merritt phenomenon (KMP) are rare and severe neoplastic lesions often associated with locally aggressive disease, consumption coagulopathy and high mortality rates. Current regimens have yet to achieve a satisfactory therapeutic effect. Thus, an effective and minimally invasive approach for treating complex KHE/KMP cases is necessary for clinical management. The present case series describes patients with KHE/KMP who underwent local suture ligation-assisted percutaneous sclerotherapy to minimise surgical trauma and ensure effective treatment. Between September 2015 and September 2017, 3 consecutive patients with KHE/KMP underwent staged local suture ligation-assisted percutaneous sclerotherapy. Of these patients, 2 presented with medical histories of corticosteroid treatment with unsatisfactory outcomes. The patients underwent a stepwise synthetic serial therapy programme consisting of percutaneous sclerotherapy and adjunctive pharmacotherapy accompanied by a suture ligation procedure. Clinical, radiological, pathological and laboratory data were analysed to evaluate the outcomes of the therapy. All patients were successfully managed with the proposed procedure. Significant relief of clinical symptoms and improvements in haematological indicators were achieved. No recurrence or complications were observed during regular follow-up (4, 19 and 28 months). In conclusion, local suture ligation-assisted percutaneous sclerotherapy was demonstrated to be a safe and effective treatment for KHE/KMP, being minimally invasive, involving simple manipulation and providing a clear treatment benefit in certain cases. Further studies involving larger sample sizes are required to thoroughly evaluate the procedure, which can potentially be used as a novel therapeutic option for KHE/KMP treatment.

Kaposiform hemangioendothelioma with Kasabach-Merritt phenomenon in an infant: Successful treatment with prednisolone, vincristine, and addition of sirolimus

A full-term newborn with kaposiform hemangioendothelioma (KHE) affecting the right thigh with thrombocytopenia due to Kasabach-Merritt phenomenon (KMP) was referred to our center. After biopsy, he rapidly evolved to severe thrombocytopenia and severe coagulopathy. Standard therapy was initiated with prednisolone and vincristine. His coagulopathy worsened to life-threatening hemorrhage necessitating aggressive blood products replacement. Sirolimus was added; he became transfusion independent with no further bleeding and reduction in tumor size. Addition of sirolimus to treatment of vascular anomalies with hemostatic complications should be considered as part of early treatment for patients with KMP/KHE.

Musculoskeletal complication in kaposiform hemangioendothelioma without Kasabach-Merritt phenomenon: clinical characteristics and management

Purpose

Musculoskeletal complications have been associated with kaposiform hemangioendothelioma (KHE) and can lead to disability and reduced quality of life. We aimed to determine the clinical characteristics of musculoskeletal complication in patients with KHE without Kasabach-Merritt phenomenon (KMP) in order to identify features that may aid clinicians in KHE treatment.

Patients and methods

We conducted a cohort study of KHE without KMP associated with musculoskeletal complication between January 2006 and February 2017 at three tertiary medical centers in China. The study included 29 nonthrombocytopenic patients with KHE and musculoskeletal complication.

Results

The mean age at diagnosis of KHE was 4.5 years (range, 0.3-50.0 years). The mean follow-up was 4.1 years (range, 0.5-9.0 years). In most cases (72.4%), decreased range of motion (ROM) appeared within 2 years of KHE onset. Associated chronic pain was reported in 12 patients. Bone-joint changes were common in patients with decreased ROM (75.9%). All the patients received at least one medical therapy including corticosteroids, vincristine, propranolol, and sirolimus. Sirolimus demonstrated the highest efficacy rate, with 94.7% of patients showing improvements in ROM and chronic pain.

Conclusion

Musculoskeletal complication can occur early in the disease course of KHE without KMP. Although no uniformly effective treatment modality was found, sirolimus demonstrated the best response in patients with KHE with decreased ROM and chronic pain.

Development of Kasabach-Merritt phenomenon following vaccination: More than a coincidence?

Kasabach-Merritt phenomenon (KMP) occurred uniquely in patients with kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). We report the clinical characteristics of two patients with KHE involving the right upper arm. The patients demonstrated rapid enlargement of the lesion with severe KMP shortly after vaccination. Sirolimus was used to treat the KHE with KMP. The patients showed a quick normalization of the platelet level. The follow-up examination revealed that the size of the mass was significantly decreased. This report raises the intriguing possibility that extrinsic factors may contribute to the development of KMP in the context of an already existing KHE.

Kaposiform haemangioendothelioma: clinical features, complications and risk factors for Kasabach-Merritt phenomenon

BACKGROUND

Few studies have reported the clinical features, complications and predictors of Kasabach-Merritt phenomenon (KMP) associated with Kaposiform haemangioendothelioma (KHE).

OBJECTIVES

To determine the clinical characteristics present at diagnosis and to identify features that may aid clinicians in managing KHE.

METHODS

We conducted a cohort study of 146 patients diagnosed with KHE.

RESULTS

KHE precursors or lesions were present at birth in 52·1% of patients. In 91·8% of patients, lesions developed within the first year of life. The median age at diagnosis of KHE was 2·3 months (interquartile range 1·0-6·0). The extremities were the dominant location, representing 50·7% of all KHEs. Among KHEs in the cohort, 63·0% were mixed lesions (cutaneous lesions with deep infiltration). Approximately 70% of patients showed KMP. A KHE diagnosis was delayed by ≥ 1 month in 65·7% of patients with KMP. Patients with KMP were more likely to have major complications than patients without KMP (P = 0·023). Young age (< 6 months), trunk location, large lesion size (> 5·0 cm) and mixed lesion type were associated with KMP in a univariate analysis. In the multivariate analysis, only age [odds ratio (OR) 11·9, 95% confidence interval (CI) 4·07-34·8; P < 0·001], large lesion size (OR 5·08, 95% CI 2·24-11·5; P < 0·001) and mixed lesion type (OR 2·96, 95% CI 1·23-7·13; P = 0·016) were associated with KMP.

CONCLUSIONS

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.

Kaposiform hemangioendothelioma in children: a benign vascular tumor with multiple treatment options

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor affecting infants and young children. Although benign, it can be associated with an aggressive locally growing tumor and/or a life-threatening Kasabach-Merritt phenomenon (KMP). To date, only reviews of limited cases have been performed. We, therefore, conducted a comprehensive literature search to collect relevant data and make recommendations for future treatment trials.

METHODS

Review of the available literature between 1993 and 2017 revealed a total of 105 publications involving 215 patients of less than 21 years of age. To this, we added 12 from our department and 4 from the Cooperative Weichteilsarkomstudie database.

RESULTS

We found that KMP was present in 79% of the infants, in 47% of the 1-5-year olds, in 43% of the 6-12-year olds, and in 10% of the 13-21-year-old patients. KMP was present in nearly all (94%) patients with retroperitoneal tumors and in all patients with extra-regional tumors. The median size of a KHE without KMP was 12 cm² as compared to 49 cm² when associated with a KMP. With complete (not further classifiable if R0 or R1) resection, all patients were cured. If inoperable, response regarding KMP/regression of tumor size was seen in 29/28% with steroid-, 47/39% with vincristine-, 44/43% with interferon alpha-, 65/61% with anti-platelet agents-, and in 97/100% with sirolimus-containing therapies.

CONCLUSIONS

Patients with progressive KHE should undergo resection whenever it is considered a safe option. If inoperable, sirolimus should be the first choice for treating KMP and reducing tumor size.

Clinical and imaging features of Kaposiform Hemangioendothelioma

OBJECTIVE

Kaposiform hemangioendothelioma (KHE) is a unique locally aggressive vascular tumor with poor prognosis. The aim of this study is to assess the clinical and imaging features of KHE, and to compare the differences between solitary and diffusive infiltrative subtype further.

METHODS

The clinical and radiological findings of a cohort of 25 cases with histologically proven KHE, between June 2011 and June 2016, were reviewed retrospectively. 7 solitary and 18 diffusive infiltrative subtypes KHE were included. The differences of clinical and imaging features between these two subtypes were compared statistically by Wilcoxon rank sum test and Fisher exact test.

RESULTS

The median age was 4 months old. 20 cases (80%) were accompanied by Kasabach-Merritt phenomenon (KMP). Most KHE located in trunk and/or extremity. The masses showed inhomogeneous echogenicity and were rich in vascularity on ultrasound; showed isoattenuation relative to muscle on unenhanced CT, isointense (n = 15) or slightly hyperintense (n = 7) T₁ weighted imaging (T₁WI) signal relative to muscle, mainly heterogeneous hyperintense or slightly hyperintense with speckled hypointense (n = 17) T₂WI signal (77%) relative to muscle, and notable (n = 15) and moderate (n = 3) enhancement. Feeding and draining vessels were revealed in 15 cases. Five masses with DWI showed slightly restricted diffusivity, with average apparent diffusion coefficient value of (1.28 ± 0.09) × 10^-3 mm² s^-1. Necrosis and hemorrhage were also found. Compared with solitary ones, diffusive infiltrative KHE were larger, more commonly accompanied by KMP and reticular lymphedema, and more frequently located in trunk and/or extremity.

CONCLUSION

Five masses with DWI showed slightly restricted diffusivity. A hypervascular mass accompanied by KMP and reticular lymphedema, with speckled hypointense signal T₂WI signal, especially in pediatric patients, is highly suggestive of the diagnosis of KHE. Advances in knowledge: Speckled hypointense signal T₂WI signal, and notable enhancement were unique features of KHE. KHE showed slightly restricted diffusivity on DWI, commonly accompanied by KMP and reticular lymphedema.

Vascular anomaly cases for the pediatric hematologist oncologists-An interdisciplinary review

Vascular anomalies (VAs) are classified as tumors or malformations depending on their clinical characteristics, pathological diagnosis, and genomic information. Diagnosis can be challenging because of the heterogeneity of clinical presentation; thus, the best diagnosis and care are provided by an interdisciplinary team of specialists. Over the past 10 years, an increasing number of pediatric hematologist/oncologists are caring for patients with VAs secondary to new medical therapy options and clinical trials. This paper focuses on complicated VA issues often seen by the pediatric hematologist/oncologist. The paper reviews clinical pearls on diagnosis, histology, radiology, and treatment options.

Episode of Kasabach-Merritt phenomenon following Japanese encephalitis vaccination: Case report

Kasabach-Merritt phenomenon (KMP) is a rare potentially life-threatening consumptive coagulopathy characterized by thrombocytopenia and hypofibrinogenemia occurring associated with the vascular tumors kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). A 10-month old male infant, diagnosed with KHE on his left leg, underwent a rapid increase of the lesion and severe thrombocytopenia, one day after the first dose of inactivated Japanese encephalitis (JE) vaccination. The episode of KMP was treated successfully by steroid. KMP is a rare complication of vaccination that physicians should be aware of. Giving up the following vaccination to provide the recurrence of KMP is not recommended.

Clinical and sonographic features of pediatric soft-tissue vascular anomalies part 1: classification, sonographic approach and vascular tumors

Sonography can be used in the management of pediatric soft-tissue vascular anomalies for diagnosing, for assessing lesion extent and for evaluating complications and response to therapy. The sonographic technique includes a combination of gray-scale imaging with color and spectral Doppler techniques. However the interpretation of the sonographic findings requires correlation with the clinical findings, some of which can be easily obtained at the time of scanning. This has to be combined with the use of appropriate nomenclature and the most updated classification in order to categorize these children into the appropriate management pathway. In this article, which is part 1 of a two-part series, the authors review the current classification of vascular anomalies, provide a clinical and a sonographic approach to these lesions, and review the most relevant clinical and sonographic features of vascular tumors including infantile and congenital hemangiomas, tufted angioma, kaposiform hemangioendothelioma, pyogenic granuloma, intramuscular capillary-type hemangioma and angiosarcoma.

Sirolimus for the treatment of progressive kaposiform hemangioendothelioma: A multicenter retrospective study

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.

Identical Presentation of Scapular Osteolysis in Two Patients with Thoracic Kaposiform Hemangioendothelioma

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that does not metastasize. We report two unique cases of KHE involving the right hemithorax and the upper ipsilateral extremity. Kasabach-Merrit phenomenon and osteolytic lesions in the scapula were observed in both cases.

Neonatal kaposiform hemangioendothelioma of the spleen associated with Kasabach-Merritt phenomenon

Kaposiform hemangioendothelioma is a rare locally aggressive vascular tumor that usually manifests during early childhood. Typically the lesion presents with skin, soft tissue and bone involvement and is characterized histologically by ill-defined nodularity and the presence of spindle cells with resemblance to Kaposi's sarcoma. We report a rare neonatal case of a splenic kaposiform hemangioendothelioma associated with Kasabach-Merritt phenomenon that was diagnosed with radiographic imaging. Because of the rapid onset of thrombocytopenia and anemia, the patient required urgent splenectomy with subsequent resolution of the blood dyscrasias.

Magnetic resonance imaging of pediatric soft-tissue vascular anomalies

Magnetic resonance (MR) imaging can be used in the management of pediatric soft-tissue vascular anomalies for diagnosing and assessing extent of lesions and for evaluating response to therapy. MR imaging studies often involve a combination of T1- and T2-weighted images in addition to MR angiography and fat-suppressed post-contrast sequences. The MR imaging features of these vascular anomalies when combined with clinical findings can aid in diagnosis. In cases of complex vascular malformations and syndromes associated with vascular anomalies, MR imaging can be used to evaluate accompanying soft-tissue and bone anomalies. This article reviews the MR imaging protocols and appearances of the most common pediatric soft-tissue vascular anomalies.

Clinical Outcomes for Systemic Corticosteroids Versus Vincristine in Treating Kaposiform Hemangioendothelioma and Tufted Angioma

A meta-analysis was performed to evaluate the efficacy and safety of systemic corticosteroids versus those of vincristine in the treatment of kaposiform hemangioendothelioma (KHE) and tufted angioma (TA).A literature search of PubMed, Embase, and Web of Science was performed for clinical studies on systemic corticosteroid versus vincristine therapies in treating KHE/TA. Pooled relative risks (RRs) and response rate with 95% confidence intervals (CIs) were used to measure outcomes. Heterogeneity, subgroup analysis, sensitivity analysis, and publication bias analysis were performed for result evaluation.Thirteen studies, comprising 344 participants, were used in the analysis. Vincristine therapy was found to be relatively more effective than systemic corticosteroids (RRs = 0.45, 95%CI: 0.35-0.58). The result of pooled adverse reactions response rate for systemic corticosteroids was 0.31 (95%CI, 0.18-0.43), significantly higher than that for vincristine, which was 0.12 (95%CI, 0.06-0.19). In subgroup analyses, factors including mean age and race of patients, and period of follow-up were examined as possible sources of heterogeneity.This is the first meta-analysis estimating the clinical outcomes of systemic corticosteroids in comparison with those of vincristine in the treatment of KHE/TA. The results showed that vincristine was considerably more effective with lower complication rates than systemic corticosteroids; thus, vincristine could be suggested as the first-line therapy for KHE/TA.