Thrombocytopenic Coagulopathy (Kasabach-Merritt Phenomenon) Is Associated with Kaposiform Hemangioendothelioma and Not with Common Infantile Hemangioma

Abstract

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.

D2-40 immunohistochemical analysis of pediatric vascular tumors reveals positivity in kaposiform hemangioendothelioma

“…The term was proposed in 1993 to delineate the entity from the infantile hemangioma. 1 The lesion was originally described in deep soft tissues; however, it frequently affects dermis and subcutis, [2][3][4] where it forms characteristic violaceous plaques. It is associated with profound thrombocytopenia (KasabachMerritt phenomenon) in more than a half of cases.…”

“…It is associated with profound thrombocytopenia (KasabachMerritt phenomenon) in more than a half of cases. 3,5 Life-threatening hemorrhage is a major complication, and mortality is high, especially for large deeply located tumors. 1,3,[5][6][7] Although kaposiform hemangioendothelioma can stabilize over time, the tumor never totally regresses, even with successful pharmacologic therapy.…”

“…3,5 Life-threatening hemorrhage is a major complication, and mortality is high, especially for large deeply located tumors. 1,3,[5][6][7] Although kaposiform hemangioendothelioma can stabilize over time, the tumor never totally regresses, even with successful pharmacologic therapy. 8 The tumor is composed of irregular lobules of small malformed vascular channels with spindled cells; often there are abnormal adjacent lymphatics.…”

Kasabach–Merritt phenomenon and prenatal counseling: a case series

“…In the perinatal period, KMP may be associated with cardiac failure or nonimmune fetal hydrops 5. The mortality rate ranges from 20% to 40% according to world literature 2, 8. On pathology, KHE or TA can be distinguished from infantile hemangioma, because of negative endothelial GLUT 1 marker 9.…”

“…Hypofibrinogenemia and fibrinolysis are secondary. Activated partial thromboplastin time is minimally high and anemia is caused by the sequestration of red blood cells in the tumor 7.While biopsy is not mandatory, an MRI is preferred for accurate diagnosis 2, 6, 14.…”