How we use angiopoietin-2 in the diagnosis and management of vascular anomalies.

The diagnosis of vascular anomalies remains challenging due to significant clinical heterogeneity and uncertain etiology. Evaluation using biopsy and/or genetic testing for somatic variants is invasive, expensive, and prone to sampling error. There is great need for noninvasive and easily measured blood laboratory biomarkers that can aid not only in diagnosis, but also management of treatments for vascular anomalies. Angiopoietin-2, a circulating blood angiogenic factor, is highly elevated in patients with kaposiform hemangioendothelioma with Kasabach-Merritt phenomenon and kaposiform lymphangiomatosis. Here, we describe our clinical experience using serum angiopoietin-2 as a biomarker for diagnosis and monitoring response to treatment.

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.

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.

How we approach coagulopathy with vascular anomalies.

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

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.

Hepatic hemangioendothelioma of infancy: clinical features of a large cohort of patients and proposed management.

PURPOSE: The management of hepatic hemangioendothelioma (HHE) may be challenging. We aimed to review a large cohort of children who presented to our centers with symptomatic HHE in the last 16 years. METHODS: We collected age at presentation, clinical features, histology, diagnostic process, management and outcome. RESULTS: Twenty seven patients (male/female 5/22), median age 13 days (1-1530) presented with hepatomegaly (24/27), cardiac failure (10/27), cutaneous hemangiomas (8/27), fever and anemia (6/27 each), vomiting (5/27), splenomegaly (4/27). The lesion was focal, multifocal, or diffuse in 9 patients of each group. The management included medical treatment (8/27), embolization (8/27), resection (3/27), observation (6/27), transplantation (2/27). After 16 months' follow-up (30 days-11 years), 23/27 (85%) were alive. Diffuse lesions (4/4), cardiac failure (4/4), type II histology (4/4), age older than 6 months at diagnosis (3/4) predicted mortality (all p < 0.01). Histology showed type 1 lesion in 3/8, type 2 in 3/8, and type 3 in 2/8 with foci of angiosarcoma. CONCLUSION: Most patients with symptomatic HHE can be managed successfully with a combination of medical, radiological and surgical treatments. Patients with diffuse lesions, late presentation, cardiac failure and type II histology have a poor outcome. LEVEL OF EVIDENCE: Diagnostic level IV. Therapeutic level IV.

Vascular tumors.

Vascular tumors are a rare subset of vascular anomalies. These are classified based on their malignant potential or local destruction potential. Classification has been historically difficult and treatment recommendations are based on case series. The purpose of this chapter is to review the presentation, pathologic and imaging characteristics. Treatment recommendations are summarized based on the current literature. Congenital and infantile hemangiomas are covered separately in a separate chapter in this issue.

Kaposiform lymphangiomatosis treated with multimodal therapy improves coagulopathy and reduces blood angiopoietin-2 levels.

Kaposiform lymphangiomatosis (KLA) is a rare, life-threatening congenital lymphatic malformation. Diagnosis is often delayed due to complex indistinct symptoms. Blood angiopoietin-2 (ANG2) levels are elevated in KLA and may be useful as a biomarker to monitor disease status. We report a 7-year-old male child with easy bruising, inguinal swelling, and consumptive coagulopathy, diagnosed with KLA. A multimodal treatment regimen of prednisone, sirolimus, vincristine, and adjunctive zoledronate was used. Plasma ANG2 levels were highly elevated at diagnosis but decreased during treatment. The patient showed significant clinical improvement over a 38-month period and normalization of ANG2 levels correlated with resolution of the coagulopathy.

Outcome of Children Treated for Infantile Hepatic Hemangioendothelioma.

PURPOSE: Infantile hepatic hemangioendothelioma (IHHE) is the most common hepatic vascular tumor in children. We report on the treatment outcome of our large single-center experience of patients with IHHE over a 9-year period. MATERIALS AND METHODS: A retrospective analysis of all IHHE patients treated at the Children Cancer Hospital Egypt from April 2008 through April 2017. RESULTS: In total, 28 patients (18 females, 10 males) were diagnosed with IHHE with a median age at diagnosis of 3 months. The lesions were multifocal (n=12), focal (n=10), and diffuse (n=6). Six (21.4%) patients initially had low T3 and T4. Eleven patients did not receive any treatment, whereas 1 patient underwent resectional surgery. Sixteen patients received drug treatment, 9 of whom responded well to first-line propranolol/prednisolone, whereas 7 patients needed salvage treatment. Twenty-five patients are alive, whereas 3 patients have died. CONCLUSIONS: Overall, patients with IHHE do well, a significant percentage of whom do not require drug therapy, particularly for those with small focal lesions. In patients with multifocal/diffuse disease, there is a high incidence of low T3 and T4 and while some of these patients did well without additional therapy, those with rapidly progressive lesions during treatment may do poorly.

Endothelial cell malignancies in infants, children and adolescents: Treatment results of three Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry.

BACKGROUND: Endothelial cell malignancies are extremely rare in childhood. New identification of genetic abnormalities (WWTR1:CAMTA1 translocation) helps to recognize potential therapeutic targets. Little is known about treatment and outcome of these patients. METHODS: Clinical course, treatment, and outcome in patients with endothelial cell malignancies treated within the Cooperative Weichteilsarkom Studiengruppe (CWS) trials CWS-91, -96, -2002P, and the Soft-Tissue Sarcoma Registry (SoTiSaR) were analyzed (1991-2019). RESULTS: Patients had angiosarcoma (AS) (n = 12), malignant epithelioid hemangioendothelioma (EHE) (n = 16), and kaposiform hemangioendothelioma (KHE) (n = 13). The median age was 5.39 years (range, 0.8-17.34); 33 patients had localized disease (LD), and 8 patients had metastatic disease. Therapy consisted of chemotherapy (CHT) (AS n = 8, EHE n = 9, KHE n = 5), interferon or new agent therapy (EHE n = 5, 2 KHE n = 2), microscopically or macroscopically complete resection (AS n = 3, EHE n = 6, KHE n = 3), and radiotherapy (AS n = 6, EHE n = 2, KHE n = 1). Two patients (KHE) had watch-and-wait strategy resulting in stable disease. Complete remission (CR) was achieved in AS (10/12; 83%), EHE (10/16; 63%), and KHE (5/13; 38%). The five-year EFS and OS for patients with AS was 64% (± 29 CI 95%) and 80% (± 25, CI 95%), with EHE 62% (± 24, CI 95%) and 78% (± 23, CI 95%), with KHE 33% (± 34, CI 95%) and 92% (± 15, CI 95%), respectively. Complete resection was a significant prognostic factor for AS, LD for EHE. CONCLUSIONS: Endothelial cell malignancies in childhood have a fair outcome with multimodal treatment. New treatment options are needed for metastic disease.

A not so harmless mass: Kaposiform hemangioendothelioma complicated by a Kasabach-Merritt phenomenon.

A vascular mass localized in the face and the neck was displayed by ultrasonography in a 38-week-old male fetus. At birth, the mass was bulky and purplish. The newborn breathed spontaneously but with severe desaturation. During laryngoscopy, we observed an obstruction of the larynx with a left-shift caused by the hemorrhagic mass. Blood analysis revealed anemia, severe thrombocytopenia, and coagulation disorders. The diagnosis of kaposiform hemangioendothelioma (KHE) complicated by a Kasabach-Merritt phenomenon (KMP) was put forward and treatment with propranolol, corticoids, and vincristine was initiated. Platelets were transfused daily for 8 days but did not resolve the thrombocytopenia. At day 8, we added sirolimus to the treatment and noted a rapid response with the normalization of the platelet count within 1 week and a significant regression of the mass. In this paper, we review the clinical and biological features of hemangioendothelioma associated with KMP and discuss its current and future treatment. Sirolimus seems to be very promising.

Kaposiform hemangioendothelioma without cutaneous involvement.

PURPOSE: We sought to characterize the clinical features and management of patients diagnosed as Kaposiform hemangioendothelioma (KHE) without cutaneous involvement. METHODS: The electronic patient chats at six Triple A hospitals in China were searched to find all patient diagnoses with KHE without cutaneous involvement. RESULTS: Of 30 patients (mean age at diagnosis, 55.6 months), 17 (56.7%) were male. Fourteen (46.7%) patients were associated with Kasabach-Merritt phenomenon (KMP). Patients with KMP were significantly more likely to have lesions involving truck compared to patients without KMP (odds ratio 10.000; 95% confidence interval 1.641-60.921; P = 0.011). Other common complication included severe anemia and decreased range of motion. In the majority of cases (93.3%), the lesions were highly infiltrative and locally invasive with ill-defined margins. Histological examination was required in all patients without KMP for precise diagnosis. In all, 16 (53.3%) patients received corticosteroid treatment, 19 (63.3%) received oral sirolimus treatment, 7 (23.3%) received intravenous vincristine, and 5 (16.7%) patients used propranolol. Patients had varied responses to conventional drugs, whereas all patients receiving sirolimus treatment had better response. In all, three patients (10%) died of disease, all presented with KMP. Feature of these recalcitrant cases (death) included young age, visceral location, extensive involvement, and lack of improvement with high-dose corticosteroids. CONCLUSIONS: Our study clearly demonstrated that KHE without cutaneous involvement could be associated with important complication, which might result in death or severe morbidity. Increased awareness of KHE without cutaneous involvement is required for early diagnosis and aggressive therapy in an attempt to prevent complication.

Expanding the Spectrum of Genetic Alterations in Pseudomyogenic Hemangioendothelioma With Recurrent Novel ACTB-FOSB Gene Fusions.

Pseudomyogenic hemangioendothelioma (PHE) is an uncommon, rarely metastasizing vascular neoplasm with predilection to affect young adults. The tumors often present as multiple nodules involving various tissue planes, including superficial and deep soft tissues as well as bone. Recurrent SERPINE1-FOSB gene fusions have been reported as the hallmark genetic abnormality in PHE, however, in our experience, a number of cases with typical histology lack this genetic abnormality. In this study, we identify a novel ACTB-FOSB gene fusion, which is as prevalent as the initial translocation reported. We selected 15 consecutive cases of PHE with typical morphologic features which had material for molecular testing. The cohort included 10 males and 5 females, ranging in age from 17 to 58 years (median age: 33 y; mean age: 35.3 y). Eight (53%) cases were located in the lower extremities (foot, calf, tibia, thigh), 5 (33%) were located in the trunk, abdomen or pelvis (abdominal wall-2, shoulder, back, ischium) and 2 (13%) were located in the upper extremity (humerus and hand). Ten (67%) cases had multifocal presentation and 5 (33%) presented as solitary lesions. Three (20%) cases were located only in the superficial dermis and subcutaneous tissues, 4 (27%) involved the superficial and deep soft tissue and 8 (53%) cases involved only the deep soft tissue and bone. Using fluorescence in situ hybridization and ARCHER fusionplex analysis we identified a novel ACTB-FOSB gene fusion in 7 cases, while the remaining 8 had the previously described SERPINE1-FOSB fusion. The clinicopathologic features and behavior of PHE associated with the ACTB-FOSB gene fusion were similar to those harboring the SERPINE1-FOSB; except that tumors with the ACTB variant were more often associated with solitary presentation. In conclusion, our results expand the spectrum of genetic alterations in PHE with a novel gene fusion identified in half of the cases. We speculate that some of the novel targeted therapies that have shown promise in SERPINE1-FOSB-positive PHE might also be beneficial in this molecular subset.