Phénomène de Kasabach-Merritt

Multimodal treatment of Kasabach-Merritt syndrome arising from tufted angioma: A case report

Kasabach-Merritt syndrome (KMS) is a rare type of vascular tumor associated with a severely decreased platelet count. No standard guidelines for the treatment of the disease have been established so far. In the present study, a 1-year-old pediatric patient with KMS arising from tufted angioma was successfully and variously treated with steroids, vincristine, surgery and propranolol for 18 months. Systemic steroids stabilized the platelet count stable, while vincristine reduced the size of the tumor. Due to unpredictable response, the patient was operated. Combination of vincristine and propranolol was introduced post-surgery to improve the severely low platelet count of the patient. Following multimodal therapy for 18 months, there has been no evidence of recurrence or metastasis during 2 years of follow-up. Currently, the patient is alive and well. The management of KMS presents a challenge, and well-designed studies are required to clearly determine the benefits and risks of multidisciplinary treatment.

[Is alfa-interferon still current in the management of Kasabach-Merritt syndrome?]

Kasabach-Merritt syndrome (KMS), characterized by thrombocytopenia, may complicate vascular tumors such as kaposiform hemangioendothelioma and tufted angioma. We report on two infants, respectively 2 months and 15 days old at the onset of symptoms, the first of whom presented with a left cervico-occipito-scapular hemangioma with parotid extension, and the second with a vascular tumor located on the left shoulder with fast extension on the left inferior hemithorax and the left arm. Thrombocytopenia (< 20 G/L) was associated in both cases. Treatment comprised first high-dose corticosteroids (2mg/kg) in association with vincristine (1mg/m(2)/week). Interferon was introduced as third-line treatment at 3 MIU/m(2)/day. In the first patient, interferon was effective both on thrombocytopenia and tumor in 2 months. In the second patient, the first interferon treatment was not effective despite 6 months of therapy. However, a second treatment 8 years later was successful. After 10 and 3 years follow-up, respectively, there were no side effects and most particularly no neurologic complications. These two observations open the discussion of the role of interferon (3 MIU/m(2)/day) as well as new therapies in the control of angiogenesis in case of failure of first-line treatment of complicated KMS vascular tumors.

[Kaposiform haemangioendothelioma associated with B-cell acute lymphoblastic leukemia]

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.