Comprehensive Analyses of Coagulation Parameters in Patients with Vascular Anomalies.

BACKGROUND: Vascular anomalies comprise a diverse group of rare diseases with altered blood flow and are often associated with coagulation disorders. The most common example is a localized intravascular coagulopathy in venous malformations leading to elevated D-dimers. In severe cases, this may progress to a disseminated intravascular coagulopathy with subsequent consumption of fibrinogen and thrombocytes predisposing to serious bleeding. A separate coagulopathy is the Kasabach-Merritt phenomenon in kaposiform hemangioendothelioma characterized by platelet trapping leading to thrombocytopenia and eventually consumptive coagulopathy. Our previous work showed impaired von Willebrand factor and platelet aggregometry due to abnormal blood flow, i.e., in ventricular assist devices or extracorporeal membrane oxygenation. With altered blood flow also present in vascular anomalies, we hypothesized that, in particular, the von Willebrand factor parameters and the platelet function may be similarly impacted. METHODS: We prospectively recruited 73 patients with different vascular anomaly entities and analyzed their coagulation parameters. RESULTS: Acquired von Willebrand syndrome was observed in both of our patients with Kasabach-Merritt phenomenon. In six out of nine patients with complex lymphatic anomalies, both the vWF antigen and activity were upregulated. Platelet aggregometry was impaired in both patients with Kasabach-Merritt phenomenon and in seven out of eight patients with an arteriovenous malformation. CONCLUSIONS: The analysis of coagulation parameters in our patients with vascular anomalies advanced our understanding of the underlying pathophysiologies of the observed coagulopathies. This may lead to new treatment options for the, in part, life-threatening bleeding risks in these patients in the future.

Congenital Infantile Fibrosarcoma Involving Pelvic Wall and Thigh Soft Tissues and Placenta, Presenting with Coagulopathy.

Infantile fibrosarcoma (IF) is a well characterized pediatric malignancy marked by gene rearrangements involving members of the NTRK family. In this report, we present a case of IF that presented in the inguinal region-proximal thigh and was initially thought to be a kaposiform hemangioendothelioma (KHE) because it presented with a bleeding diathesis thought to be Kasabach-Merritt phenomenon (KMP). Subsequently, the placental examination showed a neoplasm in the perivascular-subendothelial space of stem villi, initially thought to be myofibromatosis. Ultimately, a biopsy of the thigh mass showed IF with an NTRK3-ETV6 fusion. Subsequent FISH analysis of the placenta showed an ETV6 rearrangement confirming that it was also IF. Review of the laboratory studies suggests that disseminated intravascular coagulation may have been more likely than KMP, highlighting the difficulty in making this distinction in some cases. We believe this to be the first report of an IF presenting in a soft tissue site and the placenta, and discuss the possible mechanisms that could have allowed the IF in the leg to spread to the placenta.

Splenic Artery Embolization for Treatment of Iatrogenic Kasabach-Merritt Phenomenon Following Failed Endovascular Splenic Artery Aneurysm Repair.

Stent grafts are utilized to treat and exclude visceral arterial aneurysms while preserving flow through the vessel. Stent-associated thrombocytopenia is a rare complication not typically seen with modern stents. The following case describes the clinical presentation of stent kinking and consumptive coagulopathy. Stent-associated microangiopathic hemolytic anemia was inferred from protracted workup and exclusion of alternative diagnoses. Despite the risk of arterial puncture in the setting of profound thrombocytopenia, the patient was successfully treated with stent embolization with near immediate rebound in platelet count. This case report documents the presentation of rare stent-associated thrombocytopenia leading to challenging diagnostic evaluation and necessitating high-risk intervention.

Massive liver haemangioma causing Kasabach-Merritt syndrome in an adult.

Liver haemangiomas are common, but their size very rarely exceeds 40cm. Most people with liver haemangiomas are asymptomatic, and diagnosis is usually made incidentally during imaging for other complaints. When a liver haemangioma is symptomatic or produces complications, surgical intervention may be warranted. Kasabach-Merritt syndrome is an uncommon complication reported in certain rare vascular tumours in children, with only a few cases reported in adults. The syndrome describes a consumptive coagulopathy initiated within a vascular tumour, mainly tufted angiomas and kaposiform haemangioendotheliomas and, less commonly, giant haemangiomas. The process can extend beyond the tumour and become disseminated in certain cases due to trauma or surgery. The definitive treatment for giant liver haemangiomas can include arterial embolisation, surgical excision, hepatectomy or even liver transplantation. We report the case of a 32-year-old woman with a 42 × 32 × 27cm (18,870ml) liver haemangioma associated with Kasabach-Merritt syndrome. The diagnosis was challenging, even with proper imaging, owing to the rarity of the condition. It was achieved with an exploratory laparotomy with biopsy.

Kasabach-Merritt syndrome arising from a vascular fistula.

A 58-year-old woman presented with gum bleeding, hematuria, and cutaneous ecchymoses. Left hip replacement had been performed five years prior. The overall findings of our work-up were consistent with ongoing DIC triggered by the presence of an arterio-venous left femoral fistula. The patient was treated successfully with fresh frozen plasma, the fistula was surgically repaired and a stent was placed. On the second day, bleeding had resolved and laboratory values reverted to normal. This uncommon scenario is reminiscent of the Kasabach-Merritt syndrome and well illustrates that patients with an arterio-venous fistula can sometimes present with atypical features. The Kasabach-Merritt syndrome is reported in pediatric and adult patients with giant hemangiomas and angiosarcomas. Adult cases are described also in association with hematomas and large vascular aneurysms. The underlying pathophysiology is the sequestration and consumption of platelets and clotting factors with uncontrolled formation of microthrombi within the vascular lesion. DIC and a microangiopathic hemolytic anemia can subsequently develop. Mechanistic pathways of the Kasabach-Merritt syndrome in the context of a vascular fistula are shared with the more common causes of the syndrome. We speculate that the endothelial dysfunction and injury caused by the flow shear were the pivotal triggers of the aberrant trapping of platelets, the consumptive coagulopathy, and the formation of microthrombi within the fistula. Mortality rate can be as high as up to 40%. The Kasabach-Merritt syndrome could represent the only clinical feature of an otherwise occult vascular fistula. Emergency physicians should be aware of this condition.

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

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

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

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

A Rare Presentation of Isolated Congenital Splenic Hemangioma With Kasabach-Merritt Syndrome.

INTRODUCTION: Splenic hemangiomas (SHs) are the most common benign neoplasms of the spleen. However, they are rare in the newborn period. We present an extremely rare case of congenital SH complicated by Kasabach-Merritt syndrome. CASE PRESENTATION: A 2.93 kg male infant was delivered at term with a prenatal diagnosis of a left infrarenal mass diagnosed by ultrasound at 35 weeks of gestation. Magnetic resonance imaging demonstrated a well-defined splenic mass with multiple flow voids and scattered areas of high intensity suggestive of hemorrhage. He developed anemia, thrombocytopenia, and coagulopathy which required transfusion with packed red cells, platelets, cryoprecipitate, and fresh frozen plasma. Excision biopsy of the spleen led to resolution of anemia, thrombocytopenia, and coagulopathy. The diagnosis of SH was confirmed by histopathology. At 2 months outpatient follow-up, the patient was growing well without any evidence of tumor recurrence. CONCLUSIONS: Congenital SH is a rare entity that can be fatal if the potential complication of Kasabach-Merritt syndrome is not anticipated, evaluated, and promptly treated. Our patient had a favorable outcome with early surgical excision of the SH.

[Myelophthisis and kasabach merrit syndrome as initial manifestation of splenic angiosarcoma].

Primary splenic angiosarcoma is an extremely agressive and rare neoplasm. Manifestations as bone marrow invasion and coagulation disorders have been reported isolatedly. A 26 years-old woman presented with abdominal pain; several anemia and thrombocytopenia associated to leukoerythroblastic reaction were found in the laboratory. Consumpion coagulopathy signs and microangiopathy as schistocytes, prolonged prothrombine time, decreased fibrinogen and increased D dimer were also present. Imaging findings included a lobulated, enlarged spleen, with spontanously hyperdense areas, and heterogeneous nodules with intense, irregular enhancement after contrast administration. There were hepatic and pulmonary metastases, as well as bone lesions with conspicuous vessels. Clinical features of Kasabach-Merrit syndrome and imaging vascular neoplasm characteristics suggest a primary splenic angiosarcoma. Splenectomy and bone marrow biopsy confirmed the diagnosis of primary splenic angiosarcoma in metastatic stage.

Surgical Dead End in a Renal Transplant Recipient Associated With a Rare Thrombohemorrhagic Syndrome.

BACKGROUND: Primary breast angiosarcoma is an extremely rare malignancy. Association of this type of tumor with Kasabach-Merritt syndrome has only been reported in 3 cases in the past. To our knowledge, this is the first reported case of a solid-organ recipient. METHODS: A 53-year-old woman who underwent a deceased-donor renal transplantation 5 years previously presented with a 12-month history of a giant ulcerated lesion on her left breast. Biopsy of the overlying skin suggested primary angiosarcoma. Concurrently, the patient's bleeding from the site of the biopsy and hematology investigations indicated the presence of Kasabach-Merritt syndrome. RESULTS: The case was discussed in a multidisciplinary setting. The decision was to use anthracycline-based chemotherapy as up-front treatment to assess tumor response and gain a local benefit for a subsequent resection. After the completion of 1 cycle of chemotherapy, the patient died of cardiovascular insufficiency. Primary angiosarcoma of the breast occurs in the third to fourth decade and has been reported only in women. CONCLUSIONS: A high clinical suspicion and referral to a specialized center are necessary. Total mastectomy appears to be the only treatment conferring benefit; chemotherapy and radiation therapy are of little value.

Unusual treatment of Kasabach-Merritt syndrome secondary to hepatic hemangioma: embolization with bleomycin.

Kasabach-Merritt syndrome (KMS) is a rare complication of cavernous hemangiomas characterized with anemia, thrombocytopenia, and consumption coagulopathy. This syndrome usually develops due to superficial soft tissue hemangiomas in infancy and childhood. KMS developing secondarily to hepatic hemangioma is very rare. In this report, we aimed to present the treatment of KMS developing secondarily to giant cavernous hemangioma of the liver with transarterial chemoembolization using bleomycin.

Medical management of tumors associated with Kasabach-Merritt phenomenon: an expert survey.

Kasabach-Merritt phenomenon (KMP) is a rare consumptive coagulopathy characterized by profound thrombocytopenia and hypofibrinogenemia occurring in association with the vascular tumors kaposiform hemangioendothelioma (KHE) and tufted angioma (TA). Treatment remains challenging without consensus on the optimal medical management. The authors compiled expert opinions regarding management to establish treatment recommendations. Twenty-seven vascular anomalies centers in the United States and Canada were surveyed using 2 representative cases of KHE/TA with and without KMP. Overall response rate was 92% (25/27) with 88% completion (24/27). Most sites (23/25; 92%) do not have a standard of practice for management. The most frequent initial therapy for KHE+KMP was a combination of systemic corticosteroids and vincristine (VCR) (12/24 centers; 50%) followed by corticosteroids alone (29%). Second-line treatments were VCR (38%), rapamycin (21%), and propranolol (21%). Management of KHE/TA without KMP was variable; initial treatments included systemic corticosteroids (8/24; 33%) alone or with VCR (9/24; 38%), monitoring without medication (33%), VCR (8%), propranolol (8%), aspirin (4%), and rapamycin (4%). This survey highlights certain trends in the management of KMP-associated tumors, without standard protocols and consensus.

[Kaposiform haemangioendothelioma associated with B-cell acute lymphoblastic leukemia]. / Hémangioendothéliome kaposiforme associé à une leucémie aiguë lymphoblastique B.

BACKGROUND: Herein, we report the first case of kaposiform haemangioendothelioma (KHE) associated with acute B-lymphoblastic leukemia (B-ALL). PATIENTS AND METHODS: A five-month-old infant presented a plaque of angiomatous appearance on the forearm that had increased in volume since birth, as well as pallor and cutaneous haematomas. Kasabach-Merritt syndrome (KMS) was evoked despite hepatomegaly and considerable splenomegaly. Laboratory tests revealed severe anaemia and thrombocytopenia as well as major hyperleukocytosis with 90% blasts. Skin biopsy revealed vast vascular lobules containing cohesive fusiform endothelial cells not expressing Glut1, bound up in a dense infiltrate of B-lymphoblast cells. It was in fact KHE associated with B-ALL confirmed by the myelogram. The child was treated with the INTERFANT 2006 protocol followed by allograft of haematopoietic stem cells, which resulted in complete haematological remission. At the same time, almost total regression of KHE was noted. DISCUSSION: In this infant, KHE had an inflammatory appearance and was associated with thrombocytopenia, evocative of KMS. Analysis of blood and marrow samples resulted in a diagnosis of B-ALL. Histopathological examination of the angioma revealed a typical appearance of KHE associated with dense lymphoblastic proliferation. This appearance could have resulted either from passive contamination by circulating blast cells or from active recruitment of tumor cells at the KHE site. CONCLUSION: HK mimicking KMS may reveal B-ALL.

Kaposiform hemangioendothelioma: atypical features and risks of Kasabach-Merritt phenomenon in 107 referrals.

OBJECTIVE: To examine the presentation characteristics of patients with Kaposiform hemangioendothelioma (KHE) to describe the spectrum of disease and risk factors for Kasabach-Merritt phenomenon (KMP). STUDY DESIGN: A retrospective review of 163 patients referred to the Vascular Anomalies Center at Children's Hospital Boston for KHE between 1991 and 2009 identified 107 patients with sufficient data for inclusion. RESULTS: The prevalence of KHE in Massachusetts is ∼0.91 case per 100000 children. KHE manifested in infancy in 93% of cases, with 60% as neonates. Common presenting features included enlarging cutaneous lesion (75%), thrombocytopenia (56%), and musculoskeletal pain or decreased function (23%). Cutaneous KHE favored the extremities, especially overlying joints. In our cohort, 71% developed KMP (11% after initial presentation), and 11% of patients lacked cutaneous findings. Retroperitoneal and intrathoracic lesions, though less common, were complicated by KMP in 85% and 100% of cases, respectively. Compared with superficial lesions, KHE infiltrating into muscle or deeper was 6.3-fold more likely to manifest KMP and 18-fold higher if retroperitoneal or intrathoracic. KHE limited to bone or presenting after infancy did not manifest KMP. CONCLUSION: An enlarging cutaneous lesion is the most common presenting feature of KHE in infancy. Older patients with KHE or those lacking cutaneous manifestations present with musculoskeletal complaints or atypical symptoms. The risk of KMP increases dramatically when tumor infiltrates muscle or when KHE arises in the retroperitoneum or mediastinum.