Kaposiform hemangioendothelioma: current knowledge and future perspectives

Sirolimus for kaposiform hemangioendothelioma: Potential mechanisms of action and resistance

Kaposiform hemangioendotheliomas (KHEs) are vascular tumors that are considered borderline or locally aggressive and may lead to lethal outcomes. Traditional therapies, such as surgery and embolization, may be insufficient or technically impossible for patients with KHE. Sirolimus (or rapamycin), a specific inhibitor of mechanistic target of rapamycin, has recently been demonstrated to be very useful in the treatment of KHEs. Here, we highlight recent substantial progress regarding the effects of sirolimus on KHEs and discuss the potential mechanisms of action of sirolimus in treating this disease. The prevention of platelet activation and inflammation, along with antiangiogenic effects, the inhibition of lymphangiogenesis, the attenuation of fibrosis, or a combination of all these effects, may be responsible for the therapeutic effects of sirolimus. In addition, the mechanism of sirolimus resistance in some KHE patients is discussed. Finally, we review the somatic mutations that have recently been identified in KEH lesions, and discuss the potential of novel therapeutic targets based on these further understandings of the cellular and molecular pathogenesis of KHE.

The Evaluation, Diagnosis, and Management of Infantile Hemangiomas-A Comprehensive Review

Infantile hemangioma (IH) is the most common pediatric benign vascular tumor. Its pathogenesis is still poorly understood, and it usually appears during the first few weeks of life and follows a characteristic natural course of proliferation and involution. Most IHs are small, benign, resolve spontaneously, and do not require active treatment but only active observation. A minority of IHs are potentially problematic because they can cause life-threatening complications, permanent disfigurement, and functional impairment. Diagnosis is usually clinical, and propranolol is currently the mainstay of treatment. Other therapeutic modalities may be used alone or in combination, depending on the characteristics of the specific IH. New treatment options are being explored every day, and some are showing promising results. It is undeniable that therapeutic modalities for IHs must be selected based on the child's age, the size and location of the lesion, the presence of complications, the implementation conditions, and the possible outcomes of the treatment. The future of IH management will certainly be reflected in improved advanced imaging modalities, research into the genetic and molecular basis, the development of new pharmacological agents or techniques, and the development of standardized protocols, all to optimize outcomes with minimal side effects.

Neonatal Cutaneous Vascular Anomalies

Vascular anomalies are broadly classified into 2 categories: vascular tumors and vascular malformations. Vascular anomalies frequently present as cutaneous lesions in infants. This review summarizes vascular anomalies that most commonly present as dermatologic lesions in the neonatal period, with a focus on the clinical findings, pathophysiology and histology, relevant radiographic findings, and management of common vascular anomalies such as infantile hemangiomas, congenital hemangiomas, and Kaposiform hemangioendothelioma, along with vascular malformations, including capillary, lymphatic, venous, and arteriovenous malformations.

Hemostasis and thrombosis risks and management in vascular anomalies

The role of the hematologist in the management of vascular anomalies is evolving. Several vascular tumors and malformations are associated with complex coagulation derangements. Kaposiform hemangioendothelioma or tufted angiomas may present with a consumptive coagulopathy known as the Kasabach-Merritt phenomenon (KMP). The management of KMP is essential to reduce morbidity and mortality from this condition. Slow-flow vascular malformations (SFVM) are also frequently complicated by a coagulopathy requiring anticoagulation, especially during and after surgical procedures, and some of these conditions pose a high risk of venous thromboembolism. Pain in SFVM is also frequently responsive to anticoagulation as well. It is essential for a hematologist with expertise in vascular anomalies to assist in the management of these complex conditions as part of a multidisciplinary team to reduce morbidity and mortality. Through case-based discussions, we attempt to highlight the critical role of the hematologist in managing these anomalies.

Analysis of ultrasound and magnetic resonance imaging characteristics of kaposiform hemangioen dothelioma

OBJECTIVE

The present study aims to investigate the ultrasound and magnetic resonance imaging (MRI) characteristics of kaposiform hemangioen dothelioma (KHE).

METHODS

A retrospective analysis was conducted on the clinical data of children diagnosed with KHE through postoperative pathology. Patients were divided into two groups: the KHE group and the KHE with Kasabach-Merritt Phenomenon (KMP) group (KMP group). Laboratory indicators, ultrasound, and MRI data were collected and analyzed statistically to summarize the imaging characteristics of the disease.

RESULTS

The levels of platelets and fibrinogen in the KHE group were significantly higher than those in the KMP group, while D-dimer levels, prothrombin time, and activated partial thromboplastin time were lower (P < 0.05). Ultrasound characteristics comparison revealed that lesions extending to the fat layer (42.47% vs. 54.24%) and invading the muscle layer (38.36% vs. 69.49%) were less common in the KHE group compared to the KMP group, with the lesion diameter being smaller in the KHE group (P < 0.05). The Adler grading predominantly showed Grade II (45.21%) in the KHE group, whereas Grade III (93.22%) was more prevalent in the KMP group (P < 0.05). MRI analysis indicated that the incidence of lesions invading the muscle layer and the presence of flow voids were lower in the KHE group compared to the KMP group (P < 0.05).

CONCLUSION

KHE patients with KMP exhibit lesions that are more prone to extending into the fat layer and invading the muscle layer, with larger diameters and abundant blood flow. Additionally, the MRI images of the lesions may exhibit flow voids.

A Xenograft Model of Kaposiform Hemangioendothelioma in Nude Mice Recapitulates Kasabach-Merritt Phenomenon

BACKGROUND

Kasabach-Merritt phenomenon (KMP) is characterized by profound thrombocytopenia and consumptive coagulopathy associated with vascular tumors, such as Kaposiform hemangioendothelioma (KHE). The pathogenesis of KMP remains unclear and its treatment is challenging. In this study, we tried to establish an animal model of KMP, which may facilitate the research on the etiology and new treatment.

METHODS

A fresh sample of KHE from a one-month-old female infant with KMP was scissored into pieces and transplanted subcutaneously into the back of the nude mice. Blood routine examination was performed before the transplantation and 2, 4, 8, 12, and 16 weeks after the transplantation. Transplanted tumors were harvested 2, 4, 8, 12, and 16 weeks after the transplantation. H-E staining, immunohistochemistry staining of cluster of differentiation 31 (CD31) and alpha-smooth muscle actin (α-SMA), and ultrastructural observation were performed on the plugs.

RESULTS

Blood test showed a significant decrease in the number of platelets 2 weeks after transplantation. The number of platelets showed an overall trend of recovery from 2 weeks despite a slight decrease at 12 weeks after transplantation. There was no significant difference in the platelet count at 16 weeks after transplantation compared with the original state. H-E staining showed abundant irregular blood sinuses in the transplanted tumors with plenty of blood cells 2 weeks after the transplantation. 4, 8, and 12 weeks after transplantation, the density of blood sinuses decreased progressively. 16 weeks after transplantation, the plugs involuted into fibrous tissue. Immunohistochemistry staining showed the positive expression of CD31 in the endothelial cells and α-SMA in the perivascular cells. Ultrastructural observation also showed the features of KHE and progressive evolution of the tumors.

CONCLUSIONS

We successfully established an experimental model of KMP by the xenograft of KHE in nude mice, which manifested profound thrombocytopenia and typical pathological structure.

Vascular Tumor with Kasabach Merritt Phenomenon Treated with Steroids and Vincristine: A Retrospective Study

Vascular tumours (VT) with Kasabach-Merritt phenomenon (KMP) are rare and aggressive tumors. In absence of evidence based treatment guidelines, we studied varied presentation and response to therapy with vincristine and steroids in VT with KMP at our center. In this retrospective observational study, infants with a symptomatic/disfiguring rapidly growing VT with features of KMP were included. Demographic, treatment and outcome data was retrieved from patient file. Complete response (CR) was defined as complete clinical regression of VT with normalization of coagulopathy and thrombocytopenia. Partial response (PR) was defined as decrease in size of VT by more than 80%, absence of clinical bleed with normalization of coagulopathy and platelet count > 50,000/cumm. Five infants (2-male, 3-female) with age range (0-7 month) treated with daily prednisolone and weekly vincristine were included. The location of VT was: face (2), hemi-thorax (2) and urinary bladder (1). Four of five infants showed PR within two months; while two of these attained CR to treatment. There were no significant adverse effects over 9-32 (range) month follow-up. Two children (one in PR, one immediately after presentation) succumbed to intra-cranial hemorrhage. Combination therapy of steroids with vincristine is effective and safe in management of VT with KMP.

A Case of Superficial Kaposiform Hemangioendothelioma Treated with Oral Propranolol Combined with Topical Sirolimus

Kaposiform hemangioendothelioma(KHE) without Kasabach-Merritt phenomenon is a rare tumor primarily observed in pediatric patients; however, its documentation in the literature remains limited. We reported about a 1-year-old boy diagnosed with superficial KHE who received oral propranolol in combination with topical sirolimus and reviewed relevant reports and treatment of superficial KHE.

Soft tissue sarcoma mimicking an arteriovenous malformation - A case report and review of literature

INTRODUCTION AND IMPORTANCE

Arteriovenous malformation (AVM) is a rare condition affecting less than 5/10,000 people, with high misdiagnosis due to its heterogeneity, inconsistent nomenclature, and diverse diagnostic criteria. Understanding its prevalence in this age group is crucial for effective treatment. Here we present a case report of a patient with AVM. IRB approval and patient consent were obtained. This study was done based on SCARE criteria.

CASE PRESENTATION

A 53-year-old female patient was diagnosed with a right hip vascular mass suggestive of AVM. The patient reported painless swelling on the right hip for five years, initially increasing in size but significantly increasing in the last six months. The patient had no history of trauma, neurological or pelvic symptoms, or constitutional symptoms. An examination of the lower limbs revealed a firm, non-tender mass measuring approximately 15 × 15 cm. A thigh MRI revealed a sizable, well-rounded, lobulated soft tissue mass with a stromal structure and pronounced vascularity, indicative of a soft tissue tumor.

CLINICAL DISCUSSION

AVMs misdiagnosis is a significant issue, with 40 % of soft tissue sarcomas still misdiagnosed delaying care and leading to unnecessary measures. A 2015 study found 42.5 % of AMV patients were misdiagnosed, and 71 % were misdiagnosed as hemangiomas. Management involves multidisciplinary approaches, including radiology, sclerotherapy, surgical resection, and chemo/radiotherapy. Sirolimus may improve AVM prognosis.

CONCLUSION

Misdiagnosis of AVMs is a significant issue, with 40 % of soft tissue sarcomas still misdiagnosed. Management involves multidisciplinary approaches, including interventional radiology, sclerotherapy, surgical resection, and chemo/radiotherapy.

Coexistence of kaposiform hemangioendothelioma and capillary malformation: More than a coincidence? Two case reports

The coexistence of kaposiform hemangioendothelioma (KHE) and capillary malformation (CM) is quite rare, and few relevant studies can be found to confirm whether this phenomenon is accidental. We diagnosed and treated two such patients, revealing interesting phenomena associated with the development of vascular diseases. These cases offer the possibility that the coexistence of KHE and CM is not accidental and open up a new field of research related to pediatric vascular tumors and vascular malformations. Personalization and precision are required in the diagnosis and treatment of such patients, and the present findings provide a reliable theoretical and practical basis for further research on the pathogenesis and therapy of patients with multiple vascular diseases.

Kaposiform Hemangioendothelioma with Bone Destruction: A 16-Year Follow-Up Cohort Study of the Clinical Characteristics and Prognosis

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that often occurs in infants and young children. The goal of this study was to analyze the clinical characteristics of KHE patients with bone destruction and provide clinical guidance for diagnosis and treatment.

METHODS

We conducted a descriptive cohort study with follow-up from January 2007 to January 2023 to collect demographic information and tumor-related clinical information from KHE patients with bone destruction.

RESULTS

A total of 269 KHE patients were included in the study, of whom 70 (26.0%) patients had tumors with bone destruction. The median age at diagnosis of patients with bone destruction was 19.0 months, which was much later than that of patients without bone destruction (P < 0.001). Patients with bone destruction were more likely to have a decreased range of motion (ROM) (P < 0.001). Metaphysis involvement was more likely to occur in the lower limb bones (P = 0.039), and the lower limb bones were more likely to be associated with decreased ROM (P = 0.001). Tumors involving extracompartmental bone were more likely to have decreased ROM (P = 0.003) and exhibit the Kasabach-Merritt phenomenon (P = 0.006).

CONCLUSIONS

Based on the rarity and significant heterogeneity of KHE patients with bone destruction, we should give full play to the role of multidisciplinary teams in addressing disease to reduce the long-term complications of KHE with bone destruction and improve the quality of life of patients.

TYPE OF STUDY

Prognostic Study.

LEVEL OF EVIDENCE

Level II.

Recent advances in nanomaterial-driven strategies for diagnosis and therapy of vascular anomalies

Nanotechnology has demonstrated immense potential in various fields, especially in biomedical field. Among these domains, the development of nanotechnology for diagnosing and treating vascular anomalies has garnered significant attention. Vascular anomalies refer to structural and functional anomalies within the vascular system, which can result in conditions such as vascular malformations and tumors. These anomalies can significantly impact the quality of life of patients and pose significant health concerns. Nanoscale contrast agents have been developed for targeted imaging of blood vessels, enabling more precise identification and characterization of vascular anomalies. These contrast agents can be designed to bind specifically to abnormal blood vessels, providing healthcare professionals with a clearer view of the affected areas. More importantly, nanotechnology also offers promising solutions for targeted therapeutic interventions. Nanoparticles can be engineered to deliver drugs directly to the site of vascular anomalies, maximizing therapeutic effects while minimizing side effects on healthy tissues. Meanwhile, by incorporating functional components into nanoparticles, such as photosensitizers, nanotechnology enables innovative treatment modalities such as photothermal therapy and photodynamic therapy. This review focuses on the applications and potential of nanotechnology in the imaging and therapy of vascular anomalies, as well as discusses the present challenges and future directions.

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.

Adult-onset multifocal kaposiform hemangioendothelioma in the bone marrow, lung, liver, and brain: a case report

Kaposiform hemangioendothelioma (KHE), a rare form of vascular neoplasm, is typically seen in children. In this paper, we report a unique case of KHE replacing bone marrow tissue mimicking myeloproliferative neoplasm with additional involvement in the lung, liver, and brain in a 60-year-old Caucasian woman. The patient was initially seen in the hematology department for the chief complaint of epigastric pain and anemia. Abdominal magnetic resonance imaging (MRI) revealed mild splenomegaly with iron deposition secondary to extramedullary hematopoiesis. Additional workup was inconclusive. Subsequent bone marrow and lung biopsies eventually revealed bone marrow with extensive grade 3 fibrosis and multiple foci of low-grade vasoformative neoplasm in the lung suggestive of KHE. Although rare, KHE can present as an aggressive disease with indolent behavior in adults and can be distinguished from other vascular malignancies based on histopathology and imaging findings.

Case Report: Recurrent blepharal kaposiform hemangioendothelioma in an adult patient

Background

Kaposiform hemangioendothelioma (KHE) is a rare and invasive vascular tumor that mainly occurs in children and is rarely seen in adults. We report a case of KHE found on the eyelid of an adult patient.

Case report

We present an adult patient in whom KHE recurred 6 months after tumor resection. He underwent second surgical resection and intraoperative chemotherapy. There was no evidence of recurrence at the 3-year follow-up.

Conclusion

KHE in adults is easy to be misdiagnosed. KHE can be treated by surgical resection. Complete resection of the tumor and intraoperative chemotherapy may help prevent a recurrence.

Approach to clinically significant vascular anomalies in children

Vascular anomalies consist of tumours or malformations made up of abnormal growth or collections of blood vessels that can result in functional or cosmetic problems. While many vascular anomalies are present at birth, some do not appear until later in life, making diagnosis more challenging. Although many vascular anomalies are benign, some are associated with serious complications and may involve multiple organ systems. This article highlights the important features of clinically significant vascular anomalies to help physicians promptly identify and refer these cases to a specialised multidisciplinary team for evaluation and management. The discussion includes the various presenting complaints of vascular anomalies in children, namely, rapidly growing birthmarks, painful lesions, seizures/neurological manifestations, bleeding diathesis, cardiac/airway abnormalities and part of an overgrowth syndrome.

Kaposiform hemangioendothelioma presented with raynaud phenomenon: a case report

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm affecting infants or young children. KHE includes a spectrum of lesions, ranging from small and superficial tumors to large and invasive lesions with Kasabach-Merritt phenomenon (KMP). Currently, no published studies have reported a KHE presenting as thrombocytopenia and Raynaud phenomenon.

CASE PRESENTATION

A 2-year-old boy with right hand swelling and thrombocytopenia was admitted to our hospital. His right hand turned swelling and red, even occasionally cyanotic. This condition became worse in response to cool environments and improved with warming, and platelet counts were between 50 ~ 80 × 10^9/L. Physical examination on admission revealed the swelling and frostbite-like rash of the right-hand fingers, and the skin temperature of the right hand was lower than the left. On day 3 of admission, chest CT results showed an irregular mass on the right side of the spine. The puncture biopsy demonstrated positive CD31, D2-40, and FLI1 immunohistochemical staining, but negative GLUT1 staining, confirming the diagnosis of KHE. Furthermore, endothelin-1 (ET1) expression levels significantly increased, and eNOS and A20 expression levels significantly decreased comparing with control patients. The patient received methylprednisolone and sirolimus treatments, and his condition gradually improved during the follow-up.

CONCLUSIONS

We reported the first case of KHE presenting with thrombocytopenia and Raynaud phenomenon. The development of Raynaud phenomenon could be associated with increased ET-1 and reduced eNOS and A20 expressions. Careful differential diagnosis of hidden KHE should be considered in children with thrombocytopenia and Raynaud phenomenon.

Kaposiform hemangioendothelioma of skull base with dura invasion in a pediatric patient: a case report

Kaposiform hemangioendothelioma is an extremely rare vascular tumor which shows aggressive local growth. We present a case of rapid growing vascular skull tumor with dura invasion in a pediatric patient with neurofibromatosis type 1. A 14-year-old male complained of headache and dizziness for 1 month after minor head trauma. Brain magnetic resonance imaging (MRI) revealed a 5-cm-sized tumor in the left frontotemporal bone with internal hemorrhage and cystic changes. The gross total resection of tumor was done. At the 7-month follow-up, brain MRI revealed a recurrent skull tumor with intracranial dura mass. He underwent second surgery, and the pathologic diagnosis was suggestive of Kaposiform hemangioendothelioma. For this vascular proliferative tumor, mTOR inhibitor was treated for 6 months, and there was the recurred nodular-enhancing mass along the sphenoid ridge. After additional 2 months of medication, the following MRI revealed a decreased nodular-enhancing mass.

Rare solid tumors in a patient with Wiskott-Aldrich syndrome after hematopoietic stem cell transplantation: case report and review of literature

Background and aims

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive primary immunodeficiency disorder characterized by severe eczema, recurrent infections, and micro-thrombocytopenia. Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapeutic option for patients with classic form. The risk of developing post-transplant tumors appears to be higher in patients with WAS than in other inborn errors of immunity (IEIs), but the actual incidence is not well defined, due to the scarcity of published data.

Methods

Herein, we describe a 10-year-old patient diagnosed with WAS, treated with HSCT in the first year of life, who subsequently developed two rare solid tumors, kaposiform hemangioendothelioma and desmoid tumor. A review of the literature on post-HSCT tumors in WAS patients has been performed.

Results

The patient received diagnosis of classic WAS at the age of 2 months (Zhu score = 3), confirmed by WAS gene sequencing, which detected the nonsense hemizygous c.37C>T (Arg13X) mutation. At 9 months, patient underwent HSCT from a matched unrelated donor with an adequate immune reconstitution, characterized by normal lymphocyte subpopulations and mitogen proliferation tests. Platelet count significantly increased, even though platelet count never reached reference values. A mixed chimerism was also detected, with a residual WASP- population on monocytes (27.3%). The patient developed a kaposiform hemangioendothelioma at the age of 5. A second abdominal tumor was identified, histologically classified as a desmoid tumor when he reached the age of 10 years. Both hematopoietic and solid tumors were identified in long-term WAS survivors after HSCT.

Conclusion

Here, we describe the case of a patient with WAS who developed two rare solid tumors after HSCT. An active surveillance program for the risk of tumors is necessary in the long-term follow-up of post-HSCT WAS patients.

Platelet functional abnormalities in pediatric patients with kaposiform hemangioendothelioma/Kasabach-Merritt phenomenon

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor of infancy that is commonly associated with a life-threatening thrombocytopenic condition, Kasabach-Merritt phenomenon (KMP). Platelet CLEC-2, tumor podoplanin interaction is considered the key mechanism of platelet clearance in these patients. Here, we aimed to assess platelet functionality in such patients. Three groups of 6 to 9 children were enrolled: group A with KHE/KMP without hematologic response (HR) to therapy; group B with KHE/KMP with HR; and group C with healthy children. Platelet functionality was assessed by continuous and end point flow cytometry, low-angle light scattering analysis (LaSca), fluorescent microscopy of blood smears, and ex vivo thrombi formation. Platelet integrin activation in response to a combination of CRP (GPVI agonist) and TRAP-6 (PAR1 agonist), as well as calcium mobilization and integrin activation in response to CRP or rhodocytin (CLEC-2 agonist) alone, were significantly diminished in groups A and B. At the same time, platelet responses to ADP with or without TRAP-6 were unaltered. Thrombi formation from collagen in parallel plate flow chambers was also noticeably decreased in groups A and B. In silico analysis of these results predicted diminished amounts of CLEC-2 on the platelet surface of patients, which was further confirmed by immunofluorescence microscopy and flow cytometry. In addition, we also noted a decrease in GPVI levels on platelets from group A. In KHE/KMP, platelet responses induced by CLEC-2 or GPVI activation are impaired because of the diminished number of receptors on the platelet surface. This impairment correlates with the severity of the disease and resolves as the patient recovers.

Refractory kaposiform lymphangiomatosis relieved by splenectomy

Introduction

Kaposiform lymphangiomatosis (KLA) is a rare and complex lymphatic anomaly with a poor prognosis. There is no standard treatment, and drug therapies are the most common therapeutic method. However, some patients' symptoms become gradually aggravated despite medical treatment. Splenectomy may be an alternative option when pharmacological therapies are ineffective.

Materials and Methods

We reviewed and evaluated the cases of 3 patients with KLA who ultimately underwent splenectomy. Results: The lesions were diffusely distributed and involved the lungs and spleens of the 3 patients. Laboratory examinations revealed that all three patients had thrombocytopenia and reduced fibrinogen levels. All patients underwent symptomatic splenectomy after the medication failed. Surprisingly, their symptoms greatly improved. Histopathological investigation of the splenic lesions of the three patients confirmed the diagnosis of KLA. Immunohistochemical staining showed positivity for CD31, CD34, podoplanin, Prox-1 and angiopoietin 2 (Ang-2).

Discussion

This study aimed to review the features of KLA patients treated by splenectomy and explore the underlying link between splenectomy and prognosis. The reason for the improvement after splenectomy may be related to increased Ang-2 levels and platelet activation in patients with KLA. Future research should seek to develop more targeted drugs based on molecular findings, which may give new hope for the treatment of KLA.

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.

Oral antibiotic prophylaxis for infection in patients with vascular anomalies receiving sirolimus treatment: a multicenter retrospective study

OBJECTIVES

Patients with vascular anomalies (VAs) who receive oral sirolimus may be at high risk of infectious complications. Antibiotic prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) has been advocated. However, there have been few evidence-based analyses on this topic. This study assessed the effect of prophylactic TMP-SMZ on the incidence of infections in VA patients receiving sirolimus monotherapy.

METHODS

A retrospective, multicenter chart review was performed on all VA patients receiving sirolimus treatment from August, 2013 to January, 2021.

RESULTS

Before January 2017, 112 patients were treated with sirolimus without antibiotic prophylaxis. In the subsequent period, 195 patients were treated with TMP-SMZ for at least 12 months during sirolimus therapy. The percentage of patients with at least one serious infection during the initial 12 months of sirolimus treatment did not differ between the groups (difference, 1.1%; 95% CI - 7.0-8.0%). We observed no difference in the incidence of individual infection or total adverse events between the groups. The rate of sirolimus discontinuation due to adverse events did not differ significantly between groups.

CONCLUSIONS

We demonstrated that prophylactic TMP-SMZ does not decrease the incidence of infection or improve tolerance in VA patients receiving sirolimus monotherapy.

Case Report: Kaposiform hemangioendothelioma with PIK3CA mutation successfully treated with sirolimus

Kaposiform hemangioendothelioma (KHE) is an extremely rare, locally aggressive vascular neoplasm. The etiopathogenesis of KHE is still poorly understood. In the present study, we found a new mutation in KHE (c.685delA, p.Thr229fs). The KHE patient with the PIK3CA mutation showed complete regression after sirolimus treatment. We propose that the presence of the PIK3CA mutation in KHE may correlate with good response to sirolimus.

Benign and low-grade superficial endothelial cell neoplasms in the molecular era

Vascular tumors are the most common mesenchymal neoplasms of the skin and subcutis, and they encompass a heterogeneous group with diverse clinical, histological, and molecular features, as well as biological behavior. Over the past two decades, molecular studies have enabled the identification of pathogenic recurrent genetic alterations that can be used as additional data points to support the correct classification of these lesions. The purpose of this review is to summarize the available data related to superficially located benign and low-grade vascular neoplasms and to highlight recent molecular advances with the role of surrogate immunohistochemistry to target pathogenic proteins as diagnostic biomarkers.

Kaposiform haemangioendothelioma of the spine associated with fixed hyperlordotic deformity and Kasabach-Merritt Syndrome: a case report and literature review

Kaposiform haemangioendothelioma (KHE) is a rare childhood disease classified by the International Society for the Study of Vascular Anomalies (ISSVA) as a locally aggressive vascular tumor. It has been reported to affect any site, with a predilection for the extremities and trunk. Although it typically manifests as an enlarging cutaneous or soft tissue lesion, less than 10% of cases have no skin involvement, with the retroperitoneum being the most frequently involved extracutaneous site. Approximately twenty cases of KHE with bony involvement have been reported in the literature to date, with only five of those cases involving the spine specifically.We present a, rare case of KHE who presented with progressive fixed hyperlordotic deformity, multiple non-specific spinal lesions, and abnormal blood tests, posing a clinical and radiological diagnostic challenge. Additionally, we conducted a thorough review of the literature to compare and contrast the various multimodality imaging manifestations of KHE involving the spine.

Long-term outcomes of sirolimus treatment for kaposiform hemangioendothelioma: Continuing successes and ongoing challenges

Treatment with sirolimus, an inhibitor of the mammalian target of rapamycin pathway, has improved the prognosis of patients with kaposiform hemangioendothelioma (KHE). However, the efficacy, durability and tolerability of long-term sirolimus treatment in patients with KHE have not been well elucidated. We performed efficacy and safety assessments based on more than 4.5 years of follow-up in patients receiving sirolimus therapy for KHE. One hundred sixty-seven patients were analyzed, including 102 (61.1%) patients with the Kasabach-Merritt phenomenon (KMP). Follow-up was conducted after a median of 56.0 months. A total of 154 (92.2%) patients had a durable response to sirolimus treatment. No difference in durable response was found between patients without KMP and patients with KMP (95.4% vs 90.2%; difference, 5.2%; 95% confidence interval [CI], -4.0% to 13.1%). Rebound growth occurred in 17.3% of patients upon sirolimus discontinuation. Early treatment discontinuation (odds ratio [OR]: 3.103; 95% CI: 1.529-6.299; P = .002) and mixed lesion type (OR: 2.271; 95% CI: 0.901-5.727; P = .047) were associated with tumor rebound growth. No KHE-related deaths occurred in this cohort. At the last follow-up, approximately 17.4% of patients had active disease and/or changes in body structures to a variable extent. Serious adverse events occurred most commonly during the first year of sirolimus therapy. Follow-up of almost 4.5 years demonstrated that the efficacy of sirolimus persisted over time and that long-term treatment with sirolimus was not associated with unacceptable cumulative toxicities. However, nonresponse, tumor relapse and long-term sequelae remained challenges despite intensified and prolonged sirolimus therapy.

Case Report: CTC1 mutations in a patient with diffuse hepatic and splenic hemangiomatosis complicated by Kasabach-Merritt syndrome

Diffuse hemangiomatosis of the liver and spleen is rare. Currently, few studies are available on diffuse hepatic and splenic hemangiomatosis accompanied by Kasabach-Merritt syndrome (KMS). The conserved telomere maintenance component 1 (CTC1) gene contributes to telomere maintenance and replication by forming the telomeric capping complex. Herein, we report a case of diffuse hemangiomatosis in the liver and spleen accompanied by KMS in a 59-year-old woman who carried two novel heterozygous CTC1 variants: c.435+9A>C and c.3074C>T (p.Ala1025Val). Using next-generation sequencing, we detected mutations in the CTC1 gene in our patient, who had chief complaints of fatigue and abdominal distension complicated by severe thrombocytopenia and consumptive coagulopathy. Clinical symptoms, laboratory tests, and imaging findings led to the diagnosis of diffuse hepatic and splenic hemangiomatosis accompanied by KMS. The patient was treated with prednisone, thalidomide, and sirolimus, and her general condition was ameliorated at the 4-month follow-up with improved platelet count and coagulation function. A CTC1 gene mutation may be involved in the pathological process of vascular diseases. A combination treatment regimen of prednisone, thalidomide, and sirolimus may be effective for KMS.

A Review on Lumps, Bumps, and Birthmarks: When and Why to Refer

Skin lesions of the face, trunk, and extremities are commonly seen in the pediatric population. Although most of these lesions are benign, they can be locally destructive or interfere with normal development. Recognition and diagnosis of these lesions allow for timely workup and referral; treatment, if needed; and facilitation of parental discussions. The purpose of this article is to review common pediatric skin and soft-tissue lesions-or "lumps, bumps, and birthmarks"-to assist with diagnosis, workup, and guidelines for referral to pediatric plastic surgery. [Pediatr Ann. 2023;52(1):e23-e30.].

Case report: Transcatheter arterial embolization in a newborn with cervical rapidly involuting congenital hemangioma and Kasabach-Merritt phenomenon

Congenital hemangiomas (CHs) are rare vascular tumors and do not exhibit progressive postnatal growth. The incidence is less than 3% of all hemangiomas. Most CHs have a favorable prognosis; however, the Kasabach-Merritt phenomenon (KMP) is a rare but life-threatening complication in CHs that requires aggressive treatment. Medical treatments with corticosteroids and interferon have been suggested. Surgical resection can be considered for the treatment of complicated CHs in medically resistant lesions. Vascular embolization could be an alternative method if surgery is not considered feasible. Herein, we report a case of a 9-day-old newborn who underwent arterial embolization for a CH with KMP, combined with sirolimus treatment, and the outcome was favorable. The hemangioma completely regressed by 3 months and rapidly involuting congenital hemangioma (RICH) was diagnosed. Our successful experience with treating RICH associated with KMP revealed that RICH can have potentially serious complications although they usually resolve rapidly after birth without treatment. Surgical resection is considered to be the standard method for the treatment of medically resistant vascular tumors, but it is difficult to perform during the active phase of KMP due to acute bleeding and severe coagulopathy. Arterial embolization is feasible and can be used as an alternative to surgical resection, even in small babies.

Case Report: Pancreatic and hepatic kaposiform hemangioendothelioma presenting as consumptive coagulopathy and right hepatic atrophy

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that causes progressive angiogenesis and lymphangiogenesis, which often occurs in the skin or soft tissue, with an acute onset and rapid progression. A 4-year-old girl was admitted to our hospital with a 2-year history of thrombocytopenia, combined with right hepatic atrophy and pancreatic lesion for 3 months. At the age of two, she developed purpura and thrombocytopenia was detected, after treatment with gamma globulin and corticosteroids, the platelet count normalized, but it dropped immediately at lower doses. One year after the cessation of corticosteroids therapy, the patient presented with abdominal pain and abnormal liver function and the magnetic resonance imaging (MRI) revealed right hepatic atrophy and pancreatic occupancy, but the first liver biopsy did not reveal any positive pathological results. By analyzing the clinical manifestations in conjunction with MRI and abnormal coagulation, we considered that the patient might be diagnosed as KHE with Kasabach-Merritt phenomenon, however, sirolimus treatment was ineffective and pancreatic biopsy only showed a tendency for tumors of vascular origin. Finally, we performed a Whipple operation after the right hepatic artery embolization, histological and immunohistochemical examination suggested KHE. Three months postoperatively, the patient's liver function, pancreatic enzymes and blood clotting function gradually returned to normal. KHEs may result in significant blood loss with worsening of the coagulopathy and functional impairment, timely surgical intervention for KHE is necessary when non-invasive or minimally invasive treatment is ineffective, or the symptoms of tumor compression are obvious.

Retroperitoneal kaposiform hemangioendothelioma with kasabach-merritt phenomenon in children: A case report and review of the literature

Objective

To investigate the clinical features, diagnosis and treatment methods and prognosis of retroperitoneal Kaposiform hemangioendothelioma (R-KHE) in children.

Methods

The clinical data of an infant with R-KHE was retrospectively analyzed. Literature on R-KHE in pediatrics were retrieved in databases including Wanfang, CNKI and PubMed as of April 2022.

Results

A 1 month and 6 days female infant with R-KHE was reported. After the diagnosis was confirmed by biopsy and pathological examination, the patient was treated by interventional embolization, and a combined therapy with glucocorticoid, vincristine, sirolimus and propranolol. The patient has been followed up for 1 year and 2 months, and is still alive with tumor. Through literature search, a total of 15 children, together with the case in our report, were included. The main manifestations were diversity among those patients. 14 cases have combined Kasabach-Merritt phenomenon (KMP). 6 cases accepted surgery plus drug therapy. 4 cases accepted only surgery, and 4 cases only accepted drug therapy. While drug therapy plus radiotherapy were employed to 1 case. Improvement was observed in 11 cases, with significantly reduced tumor and survival with tumor. Tumor disappeared completely in 2 cases. While 2 cases suffered death.

Conclusion

R-KHE has diverse clinical presentations and non-specificity in symptoms and imaging examinations, and most cases accompanied with KMP. Methods for R-KHE treatment include surgical resection, interventional embolization and drug therapy. Close attention needs to be paid to the adverse reactions of the drug during the course of treatment.

Multidisciplinary management of a neonate with kaposiform hemangioendothelioma with extensive cranial fossa destruction

Kaposiform hemangioendothelioma is a rare, benign, locally destructive vascular tumor. Kasabach-Merritt phenomenon, a consumptive coagulopathy, is a life-threatening complication associated with kaposiform hemangioendothelioma. We describe a case of kaposiform hemangioendothelioma complicated by Kasabach-Merritt phenomenon in a neonate born with a large facial mass with deep extension toward the cranium and airway. The mass was not identified prenatally. The patient was a 37-week gestation age female neonate born via spontaneous vaginal delivery and noted to have a large left-sided facial mass that was not noted on the most recent prenatal ultrasound at 22 weeks gestation age. At birth, the patient was in respiratory distress and required continuous positive airway pressure support. Imaging revealed a large highly vascularized soft tissue mass adjacent to the airway with intracranial extension and bony destruction. Fine needle aspiration confirmed kaposiform hemangioendothelioma. On day of life 6, the patient was noted to have thrombocytopenia, elevated d-dimer, anemia, and hypofibrinogenemia, consistent with Kasabach-Merritt phenomenon, which resolved at day of life 12. Given the location and extent of the mass, medical therapy with single agent oral sirolimus was chosen over surgery. At 13-month follow-up, the infant is well on sirolimus therapy, and the mass has decreased in size, both clinically and on imaging. This case highlights the importance of prompt diagnosis and management of kaposiform hemangioendothelioma with extensive craniofacial and bony involvement with Kasabach-Merritt phenomenon with single oral therapy of sirolimus. Fibrinogen concentrate may be considered in the Kasabach-Merritt phenomenon refractory to cryoprecipitate.

Severe consumptive hypothyroidism in hepatic hemangioendothelioma

OBJECTIVES

Consumptive hypothyroidism may occur in hepatic hemangioendothelioma. The altered expression of deiodinases inactivates peripheral thyroid hormones. As a result, serum levels of free triiodothyronine and free thyroxine are reduced to varying degrees. There are no established recommendations for the dosage of sirolimus for this particular indication. We describe for the first time the course of treatment with low-dose sirolimus.

CASE PRESENTATION

We present a 5-week-old infant with hepatic hemangioendothelioma and severe consumptive hypothyroidism. Due to hepatic infiltration he showed signs of right heart strain. Therapy of hemangioendothelioma was initiated with propranolol and, in the absence of response, methylprednisolone was added. Treatment was continued with low-dose sirolimus (due to side effects) and propranolol. Hypothyroidism was managed with levothyroxine and liothyronine.

CONCLUSIONS

Consumptive hypothyroidism due to cutaneous hemangioma and hepatic hemangioendothelioma can be managed with propranolol and low-dose sirolimus. Treatment of severe hypothyroidism may require a combinational therapy by substitution of both T3 and T4.

Infantile Fibrosarcoma and Other Spindle Cell Neoplasms of Infancy. A Review of Morphologically Overlapping yet Molecularly Distinctive Entities

BACKGROUND

Regardless of age at presentation, many soft tissue neoplasms have overlapping histopathologic and immunophenotypic features to serve as a diagnostic challenge.

CASE REPORT

We reported a case of a spindle cell neoplasm in an infant, which was initially considered a vascular anomaly clinically and an eventual biopsy revealed marked inflammation with a spindle cell component that was resolved as an infantile fibrosarcoma with an ETV6 break-apart.

CONCLUSION

The context of this case lead to a further consideration of various other spindle cell neoplasms arising predominantly in the soft tissues during the infancy period as defined by the first two years of age. Though sharing similar morphologic features, these tumors can be categorized into several molecular genetic groups, which have provided both diagnostic and pathogenetic insights as well as treatment options in some cases.

Multifocal Kaposiform Hemangioendothelioma in a Newborn With Confirmatory Histopathology

Kaposiform hemangioendothelioma is classified as a locally aggressive vascular tumor of childhood resulting from abnormal angiogenesis and lymphangiogenesis. Most commonly, KHE presents as a single tissue mass, ranging from an erythematous papule to a violaceous indurated tumor. Definitive diagnosis requires tissue sampling with the demonstration of ill-defined nodules and fascicles of spindle-shaped D2-40 positive endothelial cells, forming slit-like vascular channels. This newborn presented with multifocal cutaneous Kaposiform hemangioendothelioma associated with Kasabach-Merritt phenomenon confirmed on histopathology with immunostaining.

Pediatric mediastinal masses

Mediastinal masses are categorized based on the International Thymic Malignancy Interest Group (ITMIG) classification into prevascular, visceral and paravertebral compartments. The schema is based on cross-sectional imaging, mainly CT, and helps with generating a differential diagnosis based on location of the mass. Up to half of all pediatric mediastinal tumors are malignant. In this review we describe mediastinal masses that are relevant to the pediatric population, as well as the role of MR imaging of mediastinal masses and its advantages.

Safety Evaluation of Oral Sirolimus in the Treatment of Childhood Diseases: A Systematic Review

Background: Sirolimus, a mammalian target of rapamycin inhibitor, has been widely used in pediatric patients, but the safety of sirolimus in pediatric patients has not been well determined. Objective: The objective of this study was to systematically evaluate prospective studies reporting the safety of sirolimus in the treatment of childhood diseases. Methods: The following data were extracted in a standardized manner: study design, demographic characteristics, intervention, and safety outcomes. Results: In total, 9 studies were included, encompassing 575 patients who received oral sirolimus for at least 6 months. Various adverse events occurred. The most common adverse event was oral mucositis (8.2%, 95% CI: 0.054 to 0.110). Through comparative analysis of the subgroups based on the targeted concentration range, we discovered that many adverse events were significantly higher in the high concentration group (≥10 ng/mL) than in the low concentration group (<10 ng/mL) (p < 0.01). More interestingly, we found that oral mucositis was more frequently reported in children with vascular anomalies than tuberous sclerosis complex. Conclusions: This study shows that oral sirolimus in the treatment of childhood diseases is safe and reliable. However, sirolimus treatment in the pediatric population should be strictly monitored to reduce the occurrence of serious or fatal adverse events.

Case report: A rare case of retroperitoneal kaposiform hemangioendothelioma with spinal involvement without abnormal platelet count in 18F-FDG PET/CT

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm that mostly appears in infancy or early childhood. Most KHE occurred on the limbs and trunk with cutaneous lesions. Approximately 12% of KHE patients manifested as deep masses and spinal involvement is extremely rare. KHE may develop into life-threatening thrombocytopenia and consumptive coagulopathy, known as the Kasabach-Merritt phenomenon (KMP), especially in patients with retroperitoneal involvement. The thrombocytopenia is usually severe, with a median platelet count of 21 × 10⁹/L at the initial presentation of KMP. Here, firstly we described a case of a 13-month-old girl with KHE who presented the movement limitation of the lower extremity caused by spinal involvement with a normal platelet count. ¹⁸F-fluorodeoxyglucose-positron emission tomography/CT (¹⁸F-FDG PET/CT) showed mildly elevated metabolism in the lesion, suggesting a probably low-grade malignant tumor. Then the patient was diagnosed with KHE by biopsy. After 6-month sirolimus monotherapy, the size of the retroperitoneal lesion was reduced significantly and the patient showed improvement in clinical symptoms. This case demonstrated the advantage of ¹⁸F-FDG PET/CT in the evaluation of disease activity in KHE and the possibility of using ¹⁸F-FDG PET/CT to guide therapy and prognostication.

Cocktail therapy with prednisolone, vincristine and sirolimus for Kasabach‑Merritt phenomenon in 10 infants

Kasabach-Merritt phenomenon (KMP) is a life-threatening condition caused by rare vascular tumors. To reduce drug resistance observed in monotherapy of KMP with prednisone, vincristine (VCR) or sirolimus, the present study evaluated the efficacy and safety of triad therapy in the treatment of KMP. A total of 10 KMP infants managed with prednisolone, VCR and sirolimus in The Second Affiliated Hospital of Xi'an Jiaotong University (Xi'an, China) between April 2017 and August 2021 were retrospectively reviewed. The three female and seven male infants with KMP underwent cocktail therapy with prednisone, VCR and sirolimus. At diagnosis, the infants, aged 49.1±41.0 days, showed laboratory test results with platelet counts 22±15.4x10⁹/l, fibrinogen 81.7±26.9 mg/dl and D-dimer 38649±13443.6 ng/ml. The average maximal diameter of the tumors at diagnosis was 84.5±25.1 mm. KMP risk is increased by large tumors with deep lesions infiltrating the muscle. Platelet counts normalized after a median 10 days (range, 5-69 days) of treatment. With combination therapy maintained for 46.8±24.4 days, ultrasound showed that the thickness of the tumors decreased by 51% from 28.9±12.1 to 13.9±6.2 mm. Neutropenia and gastrointestinal disorders were the most common adverse effects. The present study found that the cocktail therapy with prednisolone, VCR and sirolimus has favorable tolerance and efficacy for life-threatening KMP. Once a stable condition has been achieved, cocktail therapy should be replaced by sirolimus monotherapy to reduce potential side effects.

Management of pancreatic kaposiform hemangioendothelioma with sirolimus in a pediatric patient: a case report and literature review

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare locally aggressive vascular tumor. The pancreas is not a common site of KHE, especially in pediatric patients. Given that no guidelines are available for the treatment of KHE, management is currently based on expert opinions and clinical experiences. Here, we report a case of pancreatic KHE with obstructive jaundice, which was treated successfully with oral sirolimus instead of radical surgery. Additionally, a literature review on pancreatic KHE was performed to summarize prior clinical experiences and the available treatments.

CASE DESCRIPTION

A 10-month-old Chinese male infant presented with obstructive jaundice without any signs of fever, abdominal pain, or distention. A detailed consultation revealed an uneventful history. The obstructive jaundice worsened significantly during 3 weeks of conservative therapy. A pancreatic mass was identified via radiological evidence, and a laparoscopic biopsy of the tumor was performed, which confirmed the diagnosis of pancreatic KHE based on histological findings. Oral sirolimus 0.8 mg/m² twice daily was administered at a steady serum concentration of 5-15 ng/mL, which led to a shrinkage in tumor size and resolution of jaundice. The patient showed no evidence of recurrence after 1 year of follow-up and is still on sirolimus treatment, which has been tolerated well up to the time of this report.

CONCLUSIONS

The pancreas is a rare location of KHE, which is a locally aggressive vascular tumor. Diagnosis is based on histological findings, and therapy should be multidisciplinary and individualized. Although sirolimus has been very successful in the treatment of KHE even without radical surgery, the possible risks of tumor recurrence and adverse effects warrant some caution.

Rapamycin induces autophagy and apoptosis in Kaposiform hemangioendothelioma primary cells in vitro

BACKGROUND

Rapamycin has been recommended to treat Kaposiform hemangioendothelioma (KHE) with Kasabach-Merritt phenomenon (KMP), but the underlying mechanism of the clinical effect has not been established. Therefore, we determined rapamycin cytotoxicity on KHE cells in vitro and the underlying mechanism.

METHODS

KHE primary cells were derived from a tumor specimen and treated with rapamycin. Immunofluorescence was applied to identify the cells. Cell viability was measured using the Cell Counting Kit-8 (CCK-8) assay. Cell cycle and apoptosis were assessed using flow cytometry (FCM). Western blots (WB) were performed to determine phosphorylation of mammalian target of rapamycin (mTOR), p70 S6 kinase (S6K1), and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), as well light chain 3 (LC3) expression.

RESULTS

Rapamycin inhibited the growth of KHE primary cells in a dose- and time-dependent manner. Cell cycle progression was arrested in the G0/G1 phase and apoptosis was induced. WB results showed that LC3-II/I expression was significantly elevated in KHE primary cells treated with rapamycin, while the level of p-mTOR, p-S6K1, and p-4E-BP1 expression was reduced. LC3 fluorescent spots were increased in the rapamycin treatment group.

CONCLUSIONS

Rapamycin inhibited KHE primary cell proliferation, induced apoptosis and autophagy, and blocked the mTOR signaling pathway.