Kasabach-Merritt syndrome

Treatment of the Kasabach-Merritt syndrome with pegylated recombinant human megakaryocyte growth and development factor in mice: elevated platelet counts, prolonged survival, and tumor growth inhibition

Kasabach-Merritt Syndrome (KMS) is seen in children with large vascular tumors. KMS is characterized by very low platelet counts and a consumption of coagulation factors causing life-threatening complications. It has been proposed that thrombopenia in these patients is caused by intratumoral trapping of platelets. The truncated form of the cMpl-receptor ligand thrombopoietin, pegylated human megakaryocyte growth and development factor (Peg-rHuMGDF), is an agent that stimulates platelet production. We hypothesized that stimulation of the platelet production would prevent the life-threatening complications of patients with KMS owing to low platelet counts. In a mouse model of KMS, with tumors derived from a hemangioendothelioma cell line, we studied the effect of Peg-rHuMGDF. Treatment with Peg-rHuMGDF (10 microg/kg/day intraperitoneally) increased platelet counts by 7-8-fold compared with control tumor-bearing mice after 11 d of treatment (p < 0.001, n = 8). Survival was significantly increased, with 50% of treated animals alive at 1 mo versus 0% in untreated controls. Interestingly, we also observed an inhibition of tumor growth by 75% (p < 0.001, n = 8). Hematoxylin and eosin staining showed fresh fibrin clots in the treated tumors, suggesting that higher platelet counts caused intravascular thrombosis of tumor vessels. We conclude that increased platelet production in this model of KMS resulted in an antivascular tumor effect via platelet trapping. Further, we propose that thrombopoietin may be of critical value in preventing life-threatening complications from KMS.

Update on hemangiomas and vascular malformations

Hemangiomas and vascular malformations are frequently encountered in pediatric practice, especially hemangiomas and port-wine stains. These lesions may cause physical and psychological complications and it is important to recognize which lesions need to be treated and how. Great progress has been made in the classification of vascular anomalies. Angiogenesis and molecular genetics are areas of active research; recent findings relating to hemangiomas and vascular malformations are presented. New clinical features of hemangiomas are described, such as association of extensive facial hemangiomas with various malformations and the occurrence of Kasabach-Merritt phenomenon, not with common hemangiomas, but with other vascular tumors (Kaposiform hemangioendothelioma and tufted angioma). Interferon alfa is effective for treatment of complicated hemangiomas but may cause serious neurological side effects. It is to be hoped that early diagnosis of Sturge-Weber syndrome will soon be possible with new, noninvasive, functional imaging techniques. New issues surrounding pulsed dye laser therapy for port-wine stains are also discussed in this article.

Diffuse splenic and visceral hemangiomas complicated by chronic consumption coagulopathy

The case of a 7-year-old girl with a 2 year history of easy bruising associated with thrombocytopenia is reported. On admission she presented with ecchymoses, abdominal distention and splenomegaly. Hemostasis investigation revealed a consumption coagulopathy. Several radiological studies failed to confirm the diagnosis of diffuse splenic and visceral hemangiomatosis, which was eventually established by an explorative laparotomy. Platelet count and the other coagulation abnormalities progressively returned to normal after splenectomy, although the remaining hemangiomas were extensive.

Successful multimodal therapy for kaposiform hemangioendothelioma complicated by Kasabach-Merritt phenomenon: case report and review of the literature

We present the management challenge provided by a patient with kaposiform hemangioendothelioma associated with Kasabach-Merritt phenomenon. A female child presented at 14 months of age with an ecchymotic swelling of her right upper arm and axilla. Subsequently, she developed profound thrombocytopenia and hypofibrinogenemia (Kasabach-Merritt phenomenon). Biopsy of the lesion revealed kaposiform hemangioendothelioma, which has been reported as the predominant pathologic diagnosis associated with Kasabach-Merritt phenomenon. To achieve involution of the lesion and preserve function of the arm, the following interventions were involved: embolization, systemic interferon, cyclophosphamide, epsilon aminocaproic acid, and compression therapy. The clinical management of this patient was formidable until we arrived at the proper combination of therapies. Multimodal intervention may be required to manage fastidious hemangioendotheliomas of childhood, achieve clinical improvement, and prevent further morbidity.

-Neonatal Kasabach-Merritt syndrome healed by complete surgical excision of the angioma-

BACKGROUND

Kasabach-Merritt syndrome is an infrequent combination of a giant hemangioma and severe thrombocytopenia. This syndrome may be life-threatening. There are various but no definitive methods of treatment. We describe here a neonatal case cured by total excision of the tumor.

CASE REPORT

A boy was admitted at birth with a giant hemangioma of the back with thrombocytopenia. Tumor compression, corticosteroids, acetylsalicylic acid and ticlopidine were ineffective. Total surgical excision was performed on day 51, resulting in complete recovery.

CONCLUSION

Total surgical excision of a localized hemangioma in a non-functional area is probably the most appropriate and justified treatment for the Kasabach-Merritt syndrome.

Thrombocytopenic coagulopathy (Kasabach-Merritt phenomenon) is associated with Kaposiform hemangioendothelioma and not with common infantile hemangioma

Children with a large vascular tumor and associated Kasabach-Merritt coagulopathy respond inconsistently to therapy and have a high mortality rate. For this reason, we undertook a retrospective study of 21 such patients, and focused on clinical, radiographic, and histopathologic features. The male to female ratio was 1:1.6. Tumor was noted at birth in 50 percent of patients; the remainder appeared throughout infancy. The location was cervicofacial (n = 2), shoulder/upper limb (n = 4), trunk including retroperitoneum (n = 11), and lower limb (n = 4). These tumors grew rapidly to large size and were characterized by cutaneous purpura, edema, and an advancing ecchymotic margin. In contrast to common hemangioma, magnetic resonance imaging showed diffuse enhancement with ill-defined margins, cutaneous thickening, stranding of subcutaneous fat, hemosiderin deposits, and small feeding and draining vessels. All tumors were Kaposiform hemangioendothelioma (KHE); none were infantile hemangioma. Light microscopy showed irregular lobules or sheets of poorly formed, small vascular channels infiltrating and entrapping normal tissues. Characteristic features included spindle-shaped endothelial cells, diminished pericytes and mast cells, microthrombi, and hemosiderin deposits. Wide endothelial intercellular gaps and incomplete basement membranes were seen by electron microscopy. Dilated, hyperplastic, lymphaticoid channels were prominent in one tumor. KHE in 14 infants was treated with interferon alpha-2a: 6 had accelerated regression; 2 had stabilization of growth; and 6 evidenced no response. The mortality rate was 24 percent (5 of 21); this included three infants with retroperitoneal KHE. Kasabach-Merritt phenomenon does not occur with common hemangioma. Rather it is associated with the more aggressive KHE and rarely with other vascular neoplasms. Variable response to current pharmacologic therapy underscores our inadequate knowledge of the pathogenesis of thrombocytopenia in KHE.

Outcome of radiation therapy for patients with Kasabach-Merritt syndrome

PURPOSE

The efficacy of radiation therapy for Kasabach-Merritt syndrome, which is characterized by a huge hemangioma with consumption coagulopathy, remains controversial. In this study, we retrospectively investigated the treatment outcome of radiation therapy for seven neonates with Kasabach-Merritt syndrome.

METHODS AND MATERIALS

During the past 25 years we have seen seven children with Kasabach-Merritt syndrome who were treated with radiation therapy. Their ages ranged from 1 day to 5 months, with a median age of 1 month. The hemangioma was located in the extremities in four of seven children. Tumor sizes ranged from 70 cm to more than 150 cm in greatest diameter. Initial platelet counts were all less than 40,000/mm3 except for one patient. In principle, the total dose applied to the hemangioma was 8-10 Gy, with a daily dose of 1 Gy five times a week.

RESULTS

Four of seven hemangiomas responded dramatically, with a concomitant rise of the platelet count to radiation therapy. Although the remaining three hemangiomas, all of which were ill circumscribed by widespread overlying shiny, dusky purple skin, became less tense during radiation therapy. Disseminated intravascular coagulopathy was not improved, but they have responded favorably to two or three courses of radiation therapy with an extended radiation field by 1.5 years of age. As a result, all seven patients are now surviving with no evidence of hemangioma or hematological abnormalities. Shortening of the extremity was observed in three patients who received multiple courses of radiation therapy.

CONCLUSIONS

Radiation therapy appears to be one of the effective treatment options for Kasabach-Merritt syndrome despite the risk of growth delay and malignancy.

Infants with Kasabach-Merritt syndrome do not have "true" hemangiomas

OBJECTIVE

In 1940 Kasabach and Merritt described an infant with a vascular anomaly, extensive purpura, and thrombocytopenia; they called his lesion "capillary hemangioma." Hemangioma is a benign tumor that grows in infancy and is characterized by proliferation of endothelial cells and regression during childhood. Although Kasabach-Merritt syndrome (KMS) is frequently mentioned as a possible complication of hemangioma, our experience suggests that the anatomic vascular lesion underlying the thrombocytopenia is not a "true," classic, involuting type of hemangioma of infancy and childhood.

STUDY DESIGN

We reviewed the clinical and hemostasis data and the response to treatment in 22 cases of KMS, and we analyzed the biopsy specimens of 15 of them.

RESULTS

Clinically none of the 22 patients had classic hemangioma. There was no female preponderance. All patients had severe thrombocytopenia (lowest platelet count = 3000/mm3) and consumption of fibrinogen. Histologically, none had the typical "capillary," involuting type of hemangioma of infancy: they exhibited either a tufted angioma or a kaposiform hemangioendothelioma pattern; all specimens also contained numerous abnormal lymphatic-like vessels; lymphatic malformation was the major component in two patients. The infants exhibited a heterogeneous response to a number of therapeutic regimens, as noted in other reports. Severe morbidity was present; three of our patients died, and one had leg amputation. "Residua" were, in fact, residual vascular neoplasia, variable in duration, and not a stable fibrofatty residuum, as in classic involuted hemangioma; only the hematologic phenomenon was "cured" after a period of years.

CONCLUSIONS

KMS is a distinctive disease of infancy, but the underlying vascular lesion is not a "true," classic, involuting type of hemangioma of infancy. This is a different vascular tumor with a resemblance pathologically to either tufted angioma or kaposiform hemangioendothelioma in association with lymphatic-like vessels. Whether the underlying lesion in KMS is a single anatomic entity or heterogeneous cannot be definitely concluded from this study. We need a better understanding of the pathogenesis of KMS to improve our therapeutic management.

Successful management with interferon alpha-2a after prednisone therapy failure in an infant with a giant cavernous hemangioma

A giant cavernous hemangioma of the left arm with severe thrombocytopenia and consumptive coagulopathy was observed in a neonate. Initial treatment with prednisone, platelet transfusions, and clotting replacement failed to control the bleedings. The child was then treated with daily subcutaneous infusions of interferon alpha-2a. Coagulopathy rapidly improved and transfusions were drastically reduced. The hemangioma regressed progressively and disappeared after 4 months of treatment.

Treatment of an aggressive haemangiomatous lesion with alpha-interferon

We report an infant who presented with an aggressive haemangiomatous lesion of the right thigh that was treated successfully with α-interferon.

Multifocal congenital hemangiopericytomas associated with Kasabach-Merritt syndrome

A newborn male with multifocal congenital hemangiopericytomas complicated by Kasabach-Merritt syndrome was treated by excision of a large hemangiopericytoma in the right mandibular area. After excision of this lesion, the associated consumptive coagulopathy abated. Spontaneous regression of other subcutaneous tumours over the thighs and left flank was noted by age 6 months; this illustrates the benign course of most congenital hemangiopericytomas. Surgical excision of congenital hemangiopericytoma is indicated when there is a coexisting consumptive coagulopathy or for the definitive control of large lesions. For smaller lesions and in the absence of Kasabach-Merritt syndrome, the benign nature and predilection for spontaneous regression of congenital hemangiopericytomas render observation as the preferred strategy.

Chronic consumption coagulopathy due to an occult splenic haemangioma: Kasabach-Merritt syndrome

We report an 11-year-old girl with a 2-year history of bruising associated with thrombocytopenia and dysfibrinogenaemia. On admission she presented with a large subcutaneous haematoma and splenomegaly and was severely anaemic. Laboratory investigations revealed signs of consumption coagulopathy. Radiological examination showed splenic, retroperitoneal and intra-ossal haemangiomas. After splenectomy, platelet count and coagulation parameters returned to normal.

CONCLUSION

Contrary to widely held views, occult visceral haemangioma can lead to Kasabach-Merritt syndrome beyond infancy and is not necessarily associated with visible cutaneous haemangioma. It should be included in the differential diagnosis of chronic thrombocytopenia at any age. Early determination of fibrinogen degradation product levels is advised in order to detect an underlying chronic consumption coagulopathy prompted by an extensive search for multifocal haemangioma.

Kasabach-Merritt syndrome in two neonates

Two neonates with a giant hemangioma associated with thrombocytopenia (Kasabach-Marritt syndrome) have been managed at Kure National Hospital. The first case was initially difficult to distinguish from overwhelming infection or other tumors but improved after radiotherapy. The second case was resistant to radiation and steroid therapy. Magnetic resonance imaging determined a tumor extending into the surrounding soft tissues better than did enhanced computed tomography. Subtotal excision of the tumor and various drugs were effective only transiently and 51Cr-labeled platelets sequestrated into the residual hemangioma. Severe thrombocytopenia persisted for approximately 15 months requiring extra care for head and body contusions, but finally improved by treatment with platelet-active drugs such as acetylsalicylic acid, dipyridamole, and pentoxifylline.

Long term follow-up of a case of Kasabach-Merritt syndrome successfully treated with radiotherapy and corticosteroids

Kasabach-Merritt syndrome is the association of thrombocytopenia, spontaneous bleeding, and enlargement of a haemangioma. It is caused by an intense, self-perpetuating process of clot-formation and lysis within the abnormal vascular channels of the haemangioma, and results in consumption of platelets and clotting factors. Treatment involves ablation of the lesion with or without pharmacological manipulation of the coagulation and fibrinolytic systems. No single therapeutic modality is universally successful but a combination of radiotherapy and corticosteroids can result in a dramatic, immediate response with minimal long term complications.

Interferon alfa-2a therapy for life-threatening hemangiomas of infancy

BACKGROUND AND METHODS

Most hemangiomas are small, harmless birthmarks that appear soon after birth, proliferate for 8 to 18 months, and then slowly regress over the next 5 to 8 years, leaving normal or slightly blemished skin. In rare cases, hemangiomas can endanger vital structures, with a mortality of up to 60 percent. About a third of these life-threatening hemangiomas respond to treatment with corticosteroids, but for the others there is no safe and effective treatment. We evaluated the effects of daily subcutaneous injections of interferon alfa-2a (up to 3 million units per square meter of body-surface area) in 20 neonates and infants with life-threatening or vision-threatening hemangiomas that failed to respond to corticosteroid therapy.

RESULTS

In 18 of the 20 patients the hemangiomas regressed by 50 percent or more after an average of 7.8 months of treatment (range, 2 to 13). One infant died of refractory proliferation of a lesion and consumptive coagulopathy. The condition of three other patients who had large hemangiomas associated with consumptive coagulopathies that were unresponsive to conventional therapies stabilized after seven days of treatment with interferon alfa-2a alone. Transient side effects of treatment with interferon alfa-2a included fever, neutropenia (one patient), and skin necrosis (one patient). No long-term toxicity has been observed after a mean follow-up of 16 months.

CONCLUSIONS

Interferon alfa-2a appears to induce the early regression of life-threatening corticosteroid-resistant hemangiomas of infancy.

Hemangiomas and vascular malformations

Vascular lesions in the neonate and infant are categorized as hemangiomas or malformations. Although their appearances may be similar, the pathobiology, natural history, and prognosis of these lesions are different. Selected important syndromes that are characterized as hemangiomas and vascular malformations are discussed, and an update on what is new in treatment, including laser therapy, is presented.

Kasabach-Merritt syndrome

The Kasabach-Merritt syndrome includes the triad of vascular tumors, thrombocytopenia, and a hemorrhagic diathesis. The vascular tumors are usually benign but the associated coagulopathy may be life threatening. We describe a patient whose clinical course illustrates the potential difficulties in management.

The Kasabach-Merritt syndrome: treatment with intermittent pneumatic compression

A 6 week old infant presented with a giant angiomatous naevus of the leg complicated by chronic disseminated intravascular coagulation. The bleeding and laboratory abnormalities responded to intermittent pneumatic compression of the affected limb. This innocuous treatment should be considered in the Kasabach-Merritt syndrome.

Pulmonary thromboembolism from a large hemangioma in a 4-week-old infant

A female infant with an extensive congenital hemangioma of the left knee region was treated medically for consumption coagulopathy; the hemangioma began to shrink, the coagulopathy improved, and the infant was clinically well when she died suddenly at the age of 4 weeks. The cause of death was a saddle pulmonary thromboembolus which had originated in the hemangioma. This is the first documented case of fatal thromboembolism complicating a conservatively managed extensive neonatal hemangioma. Causes of neonatal thromboembolism are reviewed.