Kaposiform hemangioendothelioma: current knowledge and future perspectives

VEGF Pathway Gene Expression Profile of Proliferating versus Involuting Infantile Hemangiomas: Preliminary Evidence and Review of the Literature

Background. Infantile hemangiomas may have unexpected behavior. Initial regression (spontaneously or drug-induced) may be followed by unexplained recurrences. At this moment, there are no well-established criteria to predict infantile hemangioma reccurrences. Methods. We compared the VEGF pathway gene expression profile for one case of involuting infantile hemangioma versus one case of recurrent proliferative infantile hemangioma using TaqMan Array. Results. We found ten genes upregulated for both involuting and recurrent proliferative hemangiomas: ACTB, KRAS, MAP2K1, HRAS, NOS3, BAD, HSPB1, HPRT1, GUSB, and CASP9. Thirteen genes were downregulated for both involuting and proliferative hemangiomas: FIGF, ACTG1, GRB2, MAPKAPK2, ACTG2, MAP2K2, MAPK3, HSP90AA1, MAP2K6, NRAS, ACTA1, KDR, and MAPK1. Three genes showed divergent expression between proliferating and involuting hemangiomas. Proliferating hemangioma had MAPK14 and AKT1 gene upregulation and ACTA2 downregulation. Involuting infantile hemangioma was characterized by ACTA2 upregulation and AKT1 and MAPK14 downregulation. Conclusions. Three genes, AKT1, p38/MAPK14, and ACTA2, were found to have divergent expression in proliferating and involuting infantile hemangiomas. Excepting AKT1, which was mentioned in the last ISSVA classification (strictly related to Proteus Syndrome), none of the other genes were reported. An accurate gene expression profile mapping of infantile hemangiomas together with a gene expression-based hemangioma classification is stringently needed.

Vascular neoplasia masquerading as cellulitis and persistent hemorrhagic pericardial effusion

Tufted angioma and kaposiform hemangioendothelioma are considered to represent two ends of the spectrum of benign vascular neoplasms that predominantly present during infancy or early childhood. We report a rare case of a 5-month-old infant with complicated vascular neoplasm involving the pericardial cavity and skin over cervical region, masquerading as infective pericarditis with cellulitis. The patient responded dramatically to therapy with oral prednisolone and sirolimus, with a significant reduction of size of skin lesions and complete resolution of pericardial effusion over 8 weeks. The report also highlights the importance of a multidisciplinary team in managing such complicated cases.

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.

18F-FDG PET/CT Findings in a Woman With Kaposiform Hemangioendothelioma in the Sacrum

ABSTRACT

Kaposiform hemangioendothelioma is a rare vascular tumor with borderline malignancy and is typically diagnosed in infancy or early childhood. It most commonly affects cutaneous tissues, whereas the subtype with only primary bone involvement is extremely rare. Herein, we report a case of Kaposiform hemangioendothelioma involving the sacrum in a 37-year-old woman, with intense 18F-FDG accumulation in the lytic lesion on PET/CT. This case indicates that Kaposiform hemangioendothelioma with the primary bone involvement should be taken into consideration as a rare differential diagnosis for lytic lesions with increased 18F-FDG uptake on PET/CT.

Long-term outcomes of low-dose radiotherapy in Kasabach-Merritt syndrome

Purpose

Reports on results of radiation therapy (RT) for Kasabach-Merritt syndrome (KMS) are limited. We performed a retrospective study to evaluate the response rates and late complications and to determine the adequate RT dose for patients with KMS patients.

Materials and Methods

We studied 11 patients who received RT between October 1988 and September 2008 for KMS refractory to pharmacologic therapy. All patients had external hemangiomas and received the diagnosis of KMS within 12 months of birth. All 11 patients received steroids as the first-line therapy; eight patients additionally received interferon-α therapy, and one patient underwent surgery. Nine patients underwent single-course RT with a total dose of 4.5–8 Gy (1.5–2 Gy/fraction). Two patients received multiple courses of RT, with a cumulative total dose of 12 Gy (2 Gy/fraction) and 18 Gy (1.5 Gy/fraction), respectively.

Results

The median follow-up period was 156 months (interquartile range [IQR], 75 to 226 months). The median total dose of RT was 6 Gy, and all patients maintained complete remission until the last follow-up. An additional course of RT was performed for refractory cases or cases of local relapse after initial RT. Rapid platelet count increase after RT was seen in most patients, which returned to normalcy in a median of 20 days (IQR, 5 to 178 days). However, seven patients experienced radiation-related long-term complications.

Conclusion

Low-dose RT is effective and yields rapid response in patients with KMS. However, given growth-related late complications, RT should be carefully considered.

Sirolimus plus prednisolone vs sirolimus monotherapy for kaposiform hemangioendothelioma: a randomized clinical trial

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

Kaposiform lymphangiomatosis presenting with a Group A Streptococcus pericardial effusion

A 4-year-old child was transferred to the paediatric intensive care unit with acute respiratory failure following 4 days of fever, nausea and vomiting. Chest X-ray on admission had an enlarged cardiac silhouette and transthoracic echo confirmed a large pericardial effusion. An emergent pericardiocentesis was performed at bedside which drained nearly 1000 mL of purulent fluid. Postdrainage course was complicated by acute systolic and diastolic heart failure, thrombocytopenia and acute renal failure. A chest CT and MRI were concerning for a diffuse mediastinal soft-tissue density, so the patient underwent interventional radiology-guided biopsy complicated by haemorrhage requiring mediastinal exploration and subtotal thymectomy. Histopathology revealed changes consistent with kaposiform lymphangiomatosis and MRI demonstrated involvement of the lumbar spine and right hip. Following a course of intravenous antibiotics, the patient was started on sirolimus and prednisolone and ultimately discharged home.

Neonatal Intestinal Obstruction Due to Kaposiform Hemangioendothelioma of the Jejunum

Kaposiform hemangioendothelioma is a borderline vascular tumor usually seen in infants and children as cutaneous lesions classically associated with the Kasabach-Merritt phenomenon. Intestinal involvement is uncommon and can cause acute presentations, such as obstruction or gastrointestinal bleeding. A 5-day-old neonate presented with bilious vomiting for 2 days. The tumor was in the jejunum. Histopathological examination with immunohistochemistry of the resected jejunum showed CD34 positive endothelial lined vascular spaces infiltrating from submucosa to serosa, which is classical of kaposiform hemangioendothelioma. There was no deranged coagulation profile. This case forms an interesting cause for neonatal intestinal obstruction.

Infantile hepatic hemangiomas: looking backwards and forwards

Infantile hepatic hemangiomas (IHHs) are common benign tumors seen in the liver of infants. IHHs are true infantile hemangiomas (IHs) and have phases of proliferation and involution parallel to those of cutaneous IHs. The definition and classification of IHH are still confusing in the literature. The mechanisms during the pathogenesis of IHH have yet to be discovered. The clinical manifestations of IHH are heterogeneous. Although most IHH lesions are asymptomatic, some lesions can lead to severe complications, such as hypothyroidism, consumptive coagulopathy, and high-output congestive cardiac failure. Consequently, some patients can possibly encounter a fatal clinical condition. The heterogeneity of the lesions and the occurrence of disease-related comorbidities can make the treatment of IHH challenging. Oral propranolol is emerging as an effective systemic approach to IHH with obvious responses in tumor remission and symptom regression. However, the precise clinical characteristics and treatment strategies for patients with severe IHH have not yet been well established. Here, we summarize the epidemiology, pathogenic mechanism, clinical manifestations, diagnosis, and treatment of IHH. Recent updates and future perspectives for IHH will also be elaborated.

Vascular anomalies: clinical perspectives

Vascular anomalies are classified as vascular tumors or vascular malformations according to their cellular features and biological behavior. Detailed history and clinical assessment allow for the proper clinical diagnosis of most vascular anomalies and guide the choice of imaging to evaluate them. This article discusses the general information needed from a clinical history and physical exam to formulate a diagnosis of vascular anomaly. Then, the authors review the clinical findings from the most common vascular tumors and vascular malformations.

Kaposiform hemangioendothelioma with fatal income: Kasabach-Merritt phenomenon and hypercalcemia

Kaposiform hemangioendothelioma is a rare, borderline tumor that typically occurs during early childhood. Kasabach-Merritt phenomenon is a complication characterized by a consumptive coagulopathy resulting from the localized intravascular coagulation. Hypercalcemia generation is a rare association that was related in our case to parathyroid hormone-related protein produced by this angioma.

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.

Case report: Experience of a rare case of rebound of the Kasabach-Merritt phenomenon during sirolimus treatment in kaposiform hemangioendothelioma

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm associated with the Kasabach-Merritt phenomenon (KMP), which is a consumptive coagulopathy with associated potentially life-threatening thrombocytopenia. There are no standardized treatment protocols for the management of KHE with KMP. Moreover, there are limited reports regarding the treatment of cases of rebound. Herein, we describe a rare case of rebound of KHE/KMP, during systemic sirolimus treatment, successfully treated with embolization and vincristine infusion combined with microwave ablation.

Case Report: Bilateral symmetrical primary kaposiform hemangioendothelioma of the femur

Kaposiform hemangioendothelioma (KHE) is a rare borderline vascular tumor that usually presents as a mass of skin or deep soft tissue. We report a unique case of an 8-year-old KHE patient with bilateral symmetrical sites involving both femurs. The laboratory, radiographic, and pathological findings of the patient were minutely described. During the 6-month follow-up, the symptoms of pain and dysfunction of this patient were relieved. This study aimed to arouse clinicians' concern about the symmetrical sites of KHE patients.

Case report: Kaposi hemangioendothelioma of the right upper limb with the Kasabach-Merritt phenomenon: A potentially lethal diagnostic challenge

Kaposi hemangioendothelioma (KHE) is a rare vascular neoplasm that presents usually within the first year of life. Because of its rarity and complexity, there is often a delay in diagnosis. KHE could be associated with a life-threatening consumptive coagulopathy named the Kasabach-Merritt phenomenon (KMP). Here, we present the case of a 2-month-old girl who presented with progressive redness and swelling of her right upper limb over 6 weeks. Multiple health practitioners misdiagnosed her condition as an insect bite, cellulitis, and necrotizing fasciitis and gave treatment accordingly, which proved futile. A full blood count revealed bicytopenia of anemia and thrombocytopenia, a normal coagulation cascade, low fibrinogen, and raised D-Dimer levels. The imaging was suggestive of a high-flow vascular tumor likely to be a KHE. Subsequently, she was started on single-agent oral sirolimus with a dose increment to achieve satisfactory therapeutic levels and was treated for 1 year. She successfully completed the treatment regimen and had only transient hypertriglyceridemia, which resolved upon the completion of treatment. Currently, she is in remission 3 years after treatment. Keeping her case as an example, we would like to highlight the potentially lethal misdiagnosis of KHE with KMP, the importance of an early diagnosis of this condition, and the successful treatment outcome with single-agent sirolimus.

Kaposiform hemangioendothelioma of the bone in children and adolescents

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor that mainly occurs during infancy or early childhood. Approximately 70% of cases are complicated by Kasabach-Merritt phenomenon. Although osseous extension of the primary lesion is relatively common, primary bone involvement by KHE is rare. Given the paucity of literature on primary KHE of the bone, we report a case series of primary KHE of the bone treated at our institution and describe the clinical presentation, radiologic and pathologic findings, management and outcomes.

Analysis of angiographic characteristics of kaposiform hemangioendothelioma and investigation of the value of transcatheter arterial embolization therapy

BACKGROUND

This study aimed to analyze the angiographic characteristics of kaposiform hemangioendothelioma (KHE) and investigate the value of transcatheter arterial embolization (TAE) therapy.

METHODS

The clinical data of infants diagnosed with KHE at the department from June 2013 to June 2020 were retrospectively analyzed. Of these, 34 infants received TAE therapy. The efficacy of the treatment was evaluated 4 weeks after the therapy. The angiographic characteristics were analyzed by comparing them with the angiographic characteristics of infantile hemangioma (IH), and the times of TAE therapy and the platelet level after each TAE therapy in infants with KHE were summarized.

RESULTS

The present study showed that the capillary blush of KHE was irregular with an obscure boundary and nonuniform distribution. Many fine feeding arteries were present. The diameter of the feeding arteries was disproportionate to the volume of the tumor blush. The normal arteries were usually embedded in the tumor blush. The angiography of common IH in infants also showed tumor blush, but it was usually round with a clear boundary and uniform staining, and was distributed on 1 side of the normal arterial trunk. The infants with KHE received TAE therapy for 2 to 5 times/case, with a total of 104.0 times, with an average of 3.1±0.8/case. Among which, the platelets continued to decline for 9 times after TAE therapy and the platelets increased to ≥100×10⁹/L in 7.8±3.2 days for 95 times after TAE therapy, The average relapse time was 30.0±15.9 days.

CONCLUSIONS

The feeding arteries of KHE were numerous and fine and were not easily embolized. The application of TAE may rapidly improve the platelet level, but the long-term effect is poor.

Transarterial Embolization in Neonatal Kasabach-Merritt Syndrome

Background: Kasabach-Merritt syndrome (KMS) is characterized by large hemangiomas and persistent thrombocytopenia, which may result in visceral hemorrhage and disseminated intravascular coagulation. This study aimed to evaluate the value of transarterial embolization (TAE) in neonatal KMS patients. Patients and Methods: The clinical course of 11 neonates with KMS who underwent TAE in the Department of Neonatology, Anhui Provincal Children's Hospital, Anhui Medical University, China, were reviewed retrospectively. Results: Eleven neonates with KMS (nine male and two female) were admitted to our hospital between the age of 1 h and 6 days. All were born with progressively enlarged hemangiomas and persistent thrombocytopenia. The largest lesion had its maximum size reached at 15 × 8 × 8 cm. Eight patients had cutaneous hemangiomas (1 right face, one oropharynx, one left upper arm, two back, one left lumbar, one right lower leg, and one right thigh), and three patients had liver hemangiomas. All 11 patients underwent TAE. Nine patients underwent two TAEs, and two patients underwent only one embolization procedure. They all obtained >80% devascularization of their lesions without a major complication. The platelet count increased at 2-5 days after treatment and reached normal count and coagulation profile at 18-28 days after the TAE. Conclusions: TAE is a safe and effective alternative therapy for neonatal KMS patients.

Kaposiform Hemangioendothelioma with Kasabach-Merritt Phenomenon

A 3-y-3-mo old male child presented with massive hypertrophy and bluish-purple discoloration of the left upper limb and adjacent chest wall of 3 mo duration. There was no h/o fever, weight loss, painful large joint swelling, or any bleeding manifestations. He had spindle like nonprogressive, painless swelling of all fingers of the left hand since infancy. The child was moribund with microangiopathic hemolytic anemia, thrombocytopenia, and consumptive coagulopathy without sepsis. He received multiple transfusions of fresh frozen plasma (FFP), platelets, and packed RBC. Paradoxical worsening of symptoms with platelet transfusions and radiological evidences led to the diagnosis of a very rare congenital multifocal vascular tumor, kaposiform hemangioendothelioma (KHE) with Kasabach-Merritt phenomenon (KMP). The index case of KHE was multifocal with cutaneous lesions, osteolytic bony lesions of all phalanx and metacarpals of the left hand, and intrathoracic extension. It was successfully managed with a combination of steroid, vincristine and sirolimus.

Primary extradural tumors of the spinal column: A comprehensive treatment guide for the spine surgeon based on the 5th Edition of the World Health Organization bone and soft-tissue tumor classification

BACKGROUND

In 2020, the World Health Organization (WHO) published the 5th version of the soft tissue and bone tumor classification. Based on this novel classification system, we reviewed the current knowledge on all tumor entities with spinal manifestations, their biologic behavior, and most importantly the appropriate treatment options as well as surgical approaches.

METHODS

All tumor entities were extracted from the WHO Soft-Tissue and Bone Tumor Classification (5th Edition). PubMed and Google Scholar were searched for the published cases of spinal tumor manifestations for each entity, and the following characteristics were extracted: Growth pattern, ability to metastasize, peak age, incidence, treatment, type of surgical resection indicated, recurrence rate, risk factors, 5-year survival rate, key molecular or genetic alterations, and possible associated tumor syndromes. Surgical treatment strategies as well as nonsurgical treatment recommendations are presented based on the biologic behavior of each lesion.

RESULTS

Out of 163 primary tumor entities of bone and soft tissue, 92 lesions have been reported along the spinal axis. Of these 92 entities, 54 have the potential to metastasize. The peak age ranges from conatal lesions to 72 years. For each tumor entity, we present recommended surgical treatment strategies based on the ability to locally destruct tissue, to grow, recur after resection, undergo malignant transformation as well as survival rates. In addition, potential systemic treatment recommendations for each tumor entity are outlined.

CONCLUSION

Based on the 5th Edition of the WHO bone and soft tumor classification, we identified 92 out of 163 tumor entities, which potentially can have spinal manifestations. Exact preoperative tissue diagnosis and interdisciplinary case discussions are crucial. Surgical resection is indicated in a significant subset of patients and has to be tailored to the specific biologic behavior of the targeted tumor entity based on the considerations outlined in detail in this article.

Characterization of kaposiform lymphangiomatosis tissue-derived cells

BACKGROUND

Kaposiform lymphangiomatosis (KLA) is a recently characterized systemic lymphatic anomaly. Activation of RAS/MAPK and PI3K/AKT/mTOR pathways may affect KLA pathogenesis, but the cellular basis of KLA is unclear. Abnormal-spindle endothelial cells that express lymphatic endothelial cell (LEC) markers are characteristic of KLA histopathology. This study evaluated patient-derived KLA cells to establish their morphological and biological characteristics.

PROCEDURE

We established cell lines from primary KLA tissues of two patients with KLA and examined their morphological and functional characteristics, messenger RNA and protein expression profiles, gene mutations, and responses to inhibitors of the RAS/MAPK and PI3K/AKT/mTOR pathways.

RESULTS

Both KLA cell lines showed spindle-shaped morphology, stained positive for podoplanin (PDPN), and exhibited impaired tube-formation properties. They expressed LEC marker PDPN and mesenchymal stem cell markers (CD90, CD105) in the absence of endothelial cell markers (CD34, CD31, VWF), per real-time polymerase chain reaction. Both mTOR inhibitor rapamycin and MEK inhibitor trametinib inhibited growth of the two cell lines. A NRAS p.Q61R variant was found in one of two independent KLA tissue samples, but not in the KLA cells (per targeted next-generation sequencing); and KLA cells with this variant had elevated AKT phosphorylation levels. ERK phosphorylation levels were undetectable in both KLA cell lines.

CONCLUSIONS

Inhibition of the RAS/MAPK and PI3K/AKT/mTOR pathways may represent potential therapeutic targets in KLA. These patient-derived KLA cell lines will be useful research tools to elucidate KLA etiology, and could pave the way for basic, translational, and preclinical studies of this disease.

Antiproliferative therapy with sirolimus and propranolol for congenital vascular anomalies in newborns (Case reports)

We present a series of four newborns diagnosed with complicated congenital vascular anomalies, with different localization: Congenital lymphatic malformation (CLM) on the left hemithorax extending on the left upper limb; congenital hepatic hemangioma (CHH) with important complications in the first 7 weeks of life; Kaposiform hemangioendothelioma (KHE) of the left lower limb complicated with Kasabach Merritt phenomenon (KMM) and most probable diffuse capillary malformation with overgrowth (DCMO). All patients were treated with combined antiproliferative therapy with sirolimus and propranolol. The initial dose of sirolimus was 0.45-0.5 mg/m² with doses adjusted according to plasmatic levels. Therapeutic intervals of sirolimus were considered at plasmatic levels of 7-12 ng/ml. Our aim was to use the lowest therapeutic dose in order to avoid possible side effects. Propranolol was initiated in doses of 0.5-1.0 mg/kg/day and was increased up to 3.0 mg/kg/day depending on tolerability. Following two months, every patient showed a marked reduction in the size of the mass, improvement in overall appearance or even calcification in the liver vascular tumor. No patient showed life threatening side effects to the treatment. Hypertriglyceridemia was the only side effect noted in all patients. This is in accordance with several international studies, which try to demonstrate the importance of sirolimus in neonatal vascular malformations in monotherapy or combined with different drugs.

Kaposiform hemangioendothelioma further broadens the phenotype of PIK3CA-related overgrowth spectrum

Kaposiform hemangioendothelioma (KHE) is a rare locally aggressive mixed vascular tumor, with typical onset in early childhood and characterized by progressive angio- and lymphangiogenesis. Its etiopathogenesis and molecular bases are still unclear. Here, we report the first case of congenital KHE harboring a PIK3CA mosaic pathogenic variant (c.323G > A, p.Arg108His) in a boy with very subtle PIK3CA-related overgrowth spectrum (PROS) features. This finding provides insights into the pathophysiology of KHE, offering targeted therapeutic options by inhibition of the PI3K/Akt/mTOR pathway. We propose the inclusion of this mixed lymphatic and vascular anomaly within the PROS.

[Clinical features of Kasabach-Merritt syndrome: an analysis of 16 neonates]

OBJECTIVE

To study the clinical features, treatment, and prognosis of neonates with Kasabach-Merritt syndrome (KMS), and to provide a reference for optimizing the diagnosis and treatment of this disease.

METHODS

A retrospective analysis was performed for the clinical and follow-up data of 16 neonates with KMS who were admitted to the Anhui Children's Hospital, Anhui Medical University, from January 2016 to December 2020.

RESULTS

Of the 16 neonates, there were 13 boys (81%) and 3 girls (19%), with an age of 1 hour to 10 days on admission. Among these neonates, 13 (81%) had cutaneous hemangioma (2 in the head and face, 5 in the trunk, and 6 in the extremities) and 3 (19%) had liver hemangioma. The main clinical manifestations of bleeding tendency and scattered petechiae and ecchymosis were observed in 10 neonates (62%). All the 16 neonates had varying degrees of thrombocytopenia and coagulation disorders. They all received glucocorticoid treatment after admission and 7 (44%) of them had response, among whom 4 experienced recurrence. Among the neonates with no response to glucocorticoid treatment, 3 received sirolimus treatment, among whom 1 had the tumor volume reduced by 58.8% after 4 weeks of treatment, with platelet count and coagulation function returning to normal, while 2 had no significant reduction in tumor volume or significant increase in platelet count and achieved a tumor volume reduced by (43.7±0.4)% after 4 weeks of combined treatment with bleomycin arterial embolization, with platelet count and coagulation function returning to normal. After 4 weeks of bleomycin arterial embolization alone for 4 neonates, tumor volume was reduced by (52.0±3.4)%, and platelet count and coagulation function returned to normal. Blunt and sharp dissection was performed for 2 neonates. The tumor was removed completely during surgery in the 2 neonates, with no infection or recurrence after surgery, and platelet count and coagulation function returned to normal. The postoperative pathological examination showed Kaposiform hemangioendothelioma in 1 out of the 2 neonates.

CONCLUSIONS

KMS has characteristic clinical manifestations, histopathological features, and laboratory examination results. The KMS neonates who are not sensitive to glucocorticoids can achieve a good curative effect through arterial embolization and sirolimus treatment.

Overexpression Prox1 in HemECs resembles Kaposiform hemangioendothelioma and cytotoxicity of sirolimus in vitro

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that occurs in children. Prox1 is a specific lymphatic marker for KHE. We intended to establish a Prox1 transgenic cell line resembling KHE and investigate the mechanism of sirolimus in treating KHE.

METHODS

Prox1 was stably expressed in infantile hemangioma cell HemECs. RT-qPCR and Western blot were conducted to measure the expression of target genes. CCK-8, EdU assay, and cell cycle analysis were conducted to detect cell proliferation. Wound healing and transwell assay were used to evaluate cell migration and invasion.

RESULTS

Both mRNA and protein levels of Prox1, LYVE-1, Podoplanin were upregulated in Prox1⁺ HemECs. An acceleration of cell growth and a rise in migration and invasion were observed with Prox1 overexpression. Sirolimus inhibited cell proliferation, promoted apoptosis and led to G1 phase arrest in Prox1⁺ HemECs. The expression of p-mTOR, p-4EBP1, and p-P70S6K decreased and the ratio of LC-3 II/LC-3 I elevated after treatment of sirolimus.

CONCLUSIONS

Stable overexpression of Prox1 in HemECs induced a lymphatic endothelial reprogramming, and enhanced aggressive biological effects, partly resembled the invasion of KHE, and could serve as a novel model for KHE. Sirolimus may block mTOR-mediated pathways and induced autophagy in KHE.

A prospective multicenter study of sirolimus for complicated vascular anomalies

OBJECTIVE

Complicated vascular anomalies (VAs) can be intractable and uncontrollable using conventional treatment and can result in lethal outcomes. We undertook a prospective, multicenter phase II trial to evaluate the efficacy and safety of sirolimus in pediatric patients with complicated VAs.

METHODS

Eligible patients were required to be aged 0 to 14 years and to have a complicated VA. The patients were treated with daily oral sirolimus for 12 months. The primary endpoint was the response, which was measured using sequential volumetric magnetic resonance imaging. The secondary endpoints were the disease severity score and quality of life.

RESULTS

Of 126 patients enrolled on an intention-to-treat basis, 98 (77.8%) had had an objective response to sirolimus, with a ≥20% decrease in lesion volume. Compared with those with arteriovenous malformations, the response rates were higher (>80%) for patients with common lymphatic malformations, venous malformations, kaposiform hemangioendothelioma, and combined malformations with a prominent venous and/or lymphatic component (P < .05). Improvements in the disease severity score and quality of life were obtained in 83.3% and 79.4% of patients, respectively. The most common adverse event was mucositis in 47 patients. More serious adverse events included reversible grade 4 pneumonitis in 3 patients and grade 4 upper respiratory infection in 1 patient. All these adverse events were considered at least possibly related to the treatment.

CONCLUSIONS

Sirolimus is an apparently effective option for pediatric patients with various types of complicated VAs. Close monitoring of possible adverse events is required. The results from the present trial are the basis for future prospective studies using new therapeutic approaches.

Management of Refractory Mandibular Kaposiform Hemangioendothelioma with Sirolimus: A Case Report and Review of the Literature

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm of intermediate malignancy that generally occurs in infancy and early childhood. Typically, the lesion arises from superficial or deep soft tissues of the extremities, trunk and retroperitoneum. The paucity of reported cases of head and neck KHEs is evidence of the rarity of the disease in this region. We report on the presentation and treatment of KHE in an 11-month-old boy who presented with a mandibular lesion. We include a brief discussion about the differential diagnosis of KHE. Management involved preoperative interventional radiology, surgical excision and chemotherapeutic treatment with Sirolimus. The lesion resolved without evidence of relapse 12 months later.

Sirolimus for the treatment of kaposiform hemangioendothelioma: In a trough level-dependent way

With the accumulation of clinical practice, sirolimus is now widely viewed as an effective agent in kaposiform hemangioendothelioma (KHE) treatment using a dose based on experience. Therefore, this retrospective research aimed to provide evidence-based suggestions on the most appropriate dose and trough level of sirolimus. All unresectable KHE cases diagnosed at our center from January 2016 to December 2019 were included. Sirolimus monotherapy was initiated when there was no sign of Kasabach-Merritt phenomenon (KMP) at a dose of 0.8 mg/m² twice a day in order to keep the trough level at 5-20 ng/mL. Patients' clinical information, tumor volume change, trough level fluctuation, and complication occurrence were all recorded. Efficacy represented by tumor shrinkage speed and safety manifested by complication grades were compared between different trough level groups (5-10 vs. 10-15 vs. >15 ng/mL). Twenty-one patients (10 girls and 11 boys) were enrolled. There were eight patients in the 5-10 ng/mL group, seven in the 10-15 ng/mL group, and six in the more than 15 ng/mL group. Trough level over 10 ng/mL manifested better efficacy in tumor shrinkage (t-test, p = 0.011) while a level over 15 ng/mL had no further benefit in efficacy (t-test, p = 0.65). In addition, tumors at a central location reacted better to sirolimus (t-test, p = 0.022). No significant differences were observed in complication occurrence among different concentrations, although boys seemed to be at higher risk of more severe complications (>grade II, χ² -test, p = 0.009, odds ratio = 4.52, range = 1.20-17.24). It proved to be most efficacious in the management of KHE at a trough level between 10 and 15 ng/mL. Such concentration was safe and well tolerated.

Kaposiform Hemangioendothelioma of the Oral Cavity: A Rare Tumor with an Unusual Location

Kaposiform hemangioendothelioma is a rare neoplasm with intermediate malignant behavior, mainly affecting infants and children. Involvement head and neck is uncommon, and there are only four cases reported in the oral cavity and oropharynx. Microscopically, it is characterized by a vascular proliferation permeated by spindle-to-ovoid cells resembling Kaposi sarcoma. Immunohistochemically, the tumor is positive for CD31, CD34 and negative for D2-40. Herein we present a rare case of intraoral Kaposiform hemangioendothelioma in a 10-year-old boy.

Kaposiform haemangioendothelioma of duodenum in a neonate

Kaposiform haemangioendothelioma, an endothelial borderline tumour, is typically seen in childhood involving extremities. It has been closely associated with a consumptive coagulopathy state, Kasabach-Merritt phenomenon (KMP). Extracutaneous involvement is uncommon. Intestinal involvement is quite uncommon and can masquerade as an acute abdomen. A 24-day-old neonate presented with bilious vomiting and fever for 5 days. Sections from the resected gangrenous duodenum contained a submucosal tumour composed of infiltrating nodules of slit-like or crescentic CD34-positive spindled-to-flattened endothelial-lined vascular spaces along with zones of fibrosis. No nuclear pleomorphism or necrosis identified. The findings were classic example of kaposiform haemangioendothelioma with an absence of any deranged coagulation profile. The index case raises interest given its congenital incidental presentation at an uncommon site, like duodenum, and absence of coexistent KMP.

Vascular Birthmarks as a Clue for Complex and Syndromic Vascular Anomalies

Vascular birthmarks are common in neonates (prevalence: 20-30%) and mostly incidental findings sometimes with spontaneous regression (salmon patch and nevus simplex). Capillary malformations are found in about 1% and infantile hemangiomas are found in 4% of mature newborns. Vascular malformations are classified according to their most prominent vessel type. The term "capillary malformation" (port wine stain) includes a wide range of vascular lesions with different characteristics; they may be isolated or part of specific syndromic conditions. Part of the infantile hemangiomas and of the vascular malformations may require treatment for functional or cosmetic reasons, and in rare cases, investigations are also necessary as they represent a clue for the diagnosis of complex vascular malformation or tumors associated with extracutaneous abnormalities. Complex vascular malformations are mostly mosaicism due to early somatic mutations. Genetic advances have led to identify the main pathogenic pathways involved in this disease group. Diffuse capillary malformation with overgrowth, Klippel-Trenaunay syndrome, CLAPO syndrome, CLOVES syndrome, and megalencephaly-capillary malformation belong to the PIK3CA-related overgrowth. Capillary malformation-arteriovenous malformation underlies a fast-flow vascular malformation, sometimes manifesting as Parkes-Weber syndrome. Recognition of these different types of capillary vascular stains is sometimes difficult; however, associated findings may orient the clinicians while genetic testing may confirm the diagnosis. Lymphatic malformation frequently manifests as large masses that compress and/or infiltrate the surrounding tissues, representing a neonatal emergency when airways are involved. Infantile hemangiomas may cause functional and/or permanent esthetical damage, depending on their localization (such as periorbital area, lip, nose); large (more than 5 cm) infantile hemangiomas with a segmental distribution can be associated with obstruction or malformations of the underneath organs with complications: PHACE syndrome, LUMBAR/SACRAL syndrome, and beard infantile hemangioma. In our review, we discuss controversies regarding the international classification and emerging concepts in the field of vascular anomalies. Finally, we discuss potential developments of new, non-invasive diagnostic techniques and repurposing of target therapies from oncology. Complex and/or life-threatening vascular tumors and malformations are extremely rare events and they represent a considerable therapeutic challenge. Early recognition of clinical signs suggestive for a specific disease may improve therapeutic outcomes and avoid severe complications.

Chronic lymphedema in patients with kaposiform hemangioendothelioma: incidence, clinical features, risk factors and management

Objectives

There are no cohort studies of chronic lymphedema in patients with kaposiform hemangioendothelioma (KHE). We sought to characterize the incidence, clinical features, risk factors and management of chronic lymphedema in patients with KHE.

Methods

We conducted a multicenter retrospective analysis of patients who had a minimum of 3 years of follow-up after the onset of KHE and/or Kasabach–Merritt phenomenon (KMP). Clinical features were reviewed to determine the possible cause of chronic lymphedema. The degree of lymphedema, risk factors and management strategies were analyzed.

Results

Among the 118 patients, chronic lymphedema was confirmed by lymphoscintigraphy 1 year after the onset of KHE and/or KMP in 13 patients. In 8 patients with lymphedema, extremity swelling was evident in the presence of KHE and/or KMP. In all patients with lymphedema, a unilateral extremity was affected, along with ipsilateral KHE. Most (84.6%) patients reported moderate lymphedema. Lymphedema was more common in patients with larger (≥ 10 cm) and mixed lesions involving the extremities (P < 0.01). A history of KMP and sirolimus treatment were not predictors of lymphedema (P > 0.05). Overall, 76.9% of patients received sirolimus treatment after referral, including 53.8% who presented extremity swelling before referral. Seven (53.8%) patients received compression therapy. Five (38.5%) patients reported lymphedema-associated decreased range of motion at the last follow-up.

Conclusions

Chronic lymphedema is a common sequela of KHE and can occur independently of KMP and sirolimus treatment. Patients with large and mixed KHE involving extremities should be closely monitored for this disabling complication.

Vascular tumors of the mediastinum

Vascular tumors represent only a sliver of all tumors affecting the mediastinum, but they pose diagnostic challenges due to significant overlap among entities, ever-evolving classification schemes, and the exquisite rarity of some of the entities not only in the mediastinum but in pathology practice as a whole. Most of the vascular tumors are better known to the practice of soft tissue pathology, from which some of the knowledge of clinical behavior can be extrapolated. For example, the stratification of epithelioid hemangioendothelioma (EHE) into two biologically separate categories has effectively translated from the somatic soft tissues to the thorax. For other entities, the effective validation of soft tissue parameters is hindered by the small numbers of reported mediastinal cases. Many of the treatment modalities have also transferred over, with the key differences resting on the difficulty in achieving complete surgical resection for mediastinal tumors as opposed to those in the somatic soft tissues. Accordingly, systemic drug therapies have emerged as attractive options for some of the mediastinal vascular tumors, such as kaposiform hemangioendothelioma (KHE) and Kaposi sarcoma (KS). The categories presented herein mirror the classification scheme set forth by the 5th Edition WHO Classification of Soft Tissue and Bone Tumors. This review focuses on the biologically aggressive vascular neoplasms while limiting discussion of the benign entities to relevant comparisons in the differential diagnoses. While distinguishing among the benign entities has academic importance, in practice, the stakes are far higher for diagnosing the biologically aggressive tumors given their marked heterogeneity in clinical outcomes. Practical advice for problem areas in pathology will be reviewed alongside tumor pathobiology, including the latest in molecular diagnostics.

Kasabach-Merritt phenomenon with cellulitis in infant

Kasabach-Merritt phenomenon (KMP) is consumptive coagulopathy in large vascular lesion. This condition is specific in kaposiform haemangioendothelioma (KHE) and tufted angioma, associated with high mortality rate. This condition often involves the limbs, trunk and retroperitoneum. The clinical features that are usually found are purpura, oedema, induration and ecchymosis. A boy baby aged 9 months presented with a history of violaceous tumour that appeared on his left leg at birth that became enlarged since 6 months ago that caused discrepancy between both of his legs. The patient has his left leg massaged through alternative treatment, causing it became bruised and wounded. Blood examination showed normocytic normochromic anaemia with severe thrombocytopenia and high D-dimer. The patient was diagnosed with KMP with cellulitis and treated with oral corticosteroid, propranolol and antibiotics. Diagnosis of KMP can be made through clinical and laboratory findings. Combination therapy with corticosteroid and propranolol can be considered for KMP treatment.

The molecular pathophysiology of vascular anomalies: Genomic research

Vascular anomalies are congenital localized abnormalities that result from improper development and maintenance of the vasculature. The lesions of vascular anomalies vary in location, type, and clinical severity of the phenotype, and the current treatment options are often unsatisfactory. Most vascular anomalies are sporadic, but patterns of inheritance have been noted in some cases, making genetic analysis relevant. Developments in the field of genomics, including next-generation sequencing, have provided novel insights into the genetic and molecular pathophysiological mechanisms underlying vascular anomalies. These insights may pave the way for new approaches to molecular diagnosis and potential disease-specific therapies. This article provides an introduction to genetic testing for vascular anomalies and presents a brief summary of the etiology and genetics of vascular anomalies.

Effective surgical treatment of life-threatening huge vascular anomalies associated with thrombocytopenia and coagulopathy in infants unresponsive to drug therapy

BACKGROUND

Systemic drug therapy is generally recommended for infant huge vascular anomalies associated with thrombocytopenia and coagulopathy, but some patients are not suitable due to drug unresponsiveness or life threatening conditions before the drug works, who will need to receive surgical treatment. This study retrospectively analyzed the clinical features, imaging features, and surgical outcomes of these patients.

METHODS

The clinical data of 4 infants with huge vascular anomalies (2 vein malformations (VMs) and 2 kaposiform hemangioendothelioma (KHE)) associated with thrombocytopenia and coagulopathy treated from June 2016 to December 2017 were retrospectively analyzed. All patients received glucocorticoids, propranolol, vincristine or sirolimus treatment before admission, but the treatment was ineffective. Skin petechia, thrombocytopenia and coagulopathy were present at the time of admission. CT scanning was performed before operation. The patient's general clinical data, hematological examination results, operation time, surgical bleeding volume, blood transfusion volume and surgical complications were collected for analysis. The patients were followed up for 10-26 months.

RESULTS

CT scanning results of 2 patients showed special CT features without detectable enhancement within the lesion after CT enhanced scanning and multiple phleboliths formation. Four patients underwent surgical treatment successfully. Two patients underwent complete resection of the lesion, and 2 underwent cytoreductive surgery. Preoperative clinical symptoms such as skin petechia, thrombocytopenia and coagulopathy were normal at 1 week after surgery. Postoperative pathological results showed 2 cases of KHE and 2 cases of VMs. All patients were discharged from hospital without physical dysfunction, recurrence, or death.

CONCLUSIONS

Timely and appropriate surgical intervention can achieve satisfactory results for infants with huge VMs and KHE who were unresponsive to drug therapy or suffering from life-threatening occasion before the drug become effective.