Kaposiform hemangioendothelioma/Kasabach–Merritt syndrome. Сlinical and laboratory characteristics. Analysis of clinical cases

Kaposiform hemangioendothelioma (KHE) is a rare, usually congenital vascular tumor. It resembles Kaposi sarcoma histologically, but etiologically it is not associated with herpes simplex virus type 8. KHE refers to tumors of intermediate malignancy degree. The most severe complication is the addition of thrombocytopenia and consumption coagulopathy, i.e. development of the Kasabach–Merritt syndrome/phenomenon (KMS), which determines the high mortality rate (up to 30%) in this histological variant. The frequency of occurrence of KMS is unknown. Over Patients with KHE/KMS have clear clinical and laboratory characteristics, which in most cases allow make to diagnose without histological confirmation. Over 7-year follow-up period 32 patients with KHE were registered in our center; in 90.6% of cases it was complicated by the development of KMS. The study was approved by the Independent Ethics Committee and Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. In the most of patients the tumor was detected from birth (84%), in half of the cases (52%) hematological complications were diagnosed simultaneously with the detection of the tumor. Сommon local complications include joint contractures, destruction of bone tissue, and invasion of neighboring organs. The half of the patients had changes in the heart function: from minor cardiac pathology to congenital defects. In addition, there were clinical and instrumental changes associated with volume overload: an increase in liver size, myocardial hypertrophy. Despite the presence of clear clinical and laboratory characteristics of KMS, some cases require differential diagnosis with other vascular anomalies accompanied by thrombocytopenia and consumption coagulopathy – with congenital hemangiomas (rapidly involuting congenital hemangioma), multifocal lymphangioendotheliomatosis with thrombocytopenia, kaposiform lymphangiomatosis, venous malformations. The parents of the patients agreed to use the information, including photos of children, in scientific research and publications.