Information on the following diseases can be found in the Related Disorders section of this report:

• Coagulopathy and other vascular malformations
• cavernous hemangioma
• consumptive coagulopathy

The initial symptoms of the condition may be tiny red spots under the skin (petechiae), bruises and bleeding. The vascular tumor associated with Kasabach-Merritt phenomenon is not a common hemangioma, but is either a tufted angioma or a kaposiform hemangioendothelioma. These vascular tumors can occur on an extremity, in the chest, neck, abdomen or retroperitoneal area. They are usually focal but can be multifocal. They can cause just a bruise or petechiae on the skin surface or they can be very violaceous with a purpuric color and be firm, warm and tense. If the tumor is internal the abdomen or pelvis may appear bruised. Profound thrombocytopenia can cause increased bruising in other areas with petechiae. Anemia can occur which will cause a paleness to the skin, a rapid heart rate(tachycardia) and difficulties feeding or a change in temperament. The lesion can increase in size becoming more violacious cutaneously or creating more problems internally (difficulty breathing, liver failure, abdominal obstruction. Significant life threatening bleeding can occur.

The cause of Kasabach-Merritt phenomenon is unknown. It is believed to be secondary to sequestration or trapping of platelets into the tumor.

Kasabach-Merritt phenomenon is a rare disorder that affects males and females equally The diagnosis is most often made during infancy but older children and adults have been reported to develop the condition.
.

Symptoms of the following disorders can be similar to those of Kasabach-Merritt phenomenon. Comparisons may be useful for a differential diagnosis:


Vascular Malformations
These are abnormal collections of vessels that are congenital. Large malforamtions such as venous or venous lymphatic lesions and multiple lesions can causes coagulopathies with low platelet counts and other coagulation proteins. This coagulopathy is not Kasabach-Merritt phenomenon.

Hemangiomas
These rare vascular tumors were misdiagnosed as hemangiomas in the past. Hemangiomas are benign tumors with endothelial proliferation which are usually not present at birth but proliferate and grow over a 4 to 6 month period of time and then stabilize and involute. Hemangiomas are not associated with any coagulopathy or thrombocytopenia.

Essential Thrombocytopenia is a rare blood disease affecting the platelets of the blood. This causes clotting abnormalities. It is characterized by an abnormally low platelet count and a shorter than normal (ten days) platelet survival time. Major symptoms include a tendency to bleed excessively into the skin or mucous membranes, especially during menstruation. There are many different reasons for the decreased marrow production and platelet destruction that causes this disorder. (For more information on this disorder, choose "Essential Thrombocytopenia" as your search term in the Rare Disease Database.)

Diagnosis
The diagnosis of Kasabach-Merritt phenomenon is based on the association of Kaposiform hemangioendothelioma/tufted angioma, profound thrombocytopenia.
The vascular tumor may be observed on physical examination or documented by imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT). The thrombocytopenia is diagnosed by complete blood count (CBC).

Treatment
Kasabach-Merritt phenomenon is treated with corticosteroids,vincristine interferon, aspirin, and antiplatelet drugs such as Ticlopidine. Sometimes a combination of medications needs to be given. Other therapies include embolization therapy. IF the lesion can be surgically removed that is the treatment of choice.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com

Cheerva AC; Kasabach-Merritt Syndrome; eMedicine; http://www.emedicine.com/MED/topic1221.htm, Last Update: 6/22/06, Accessed 2/08.

Vasquez M-P, Kasabach-Merritt syndrome; Orphanet; http://www.orpha.net//consor/cgi-bin/OC_Exp.php?Lng=GB&Expert=2330, Last Update: 5/06, Accessed 2/08.

McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM); http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=141000, Last Update: 11/27/07, Accessed 2/08.

Enjolras O, Wassef M, Mazoyer E, et al. Inafants with Kasabach-Merritt syndrome do not have ‘true' hemangiomas. J Pediat 130:631-640, 1997; 130(4):631-40.

Enjolras O, Wassef M, Mazoyer E, et al. Infants with Kasabach-Merritt syndrome do not have "true" hemangiomas. J Pediatr. 1997;130(4):631-40.

Ezekowitz RA, Mulliken JB, Folkman J. Interferon alfa-2a therapy for life-threatening hemangiomas of infancy. N Engl J Med. 1992;:326(22):1456-63.

George M, Singhal V, Sharma V, Nopper AJ. Successful surgical excision of a complex vascular lesion in an infant with Kasabach-Merritt syndrome. Pediatr Dermatol. 2002;19(4):340-4.

Haisley-Royster C, Enjolras O, Frieden IJ, et al. Kasabach-merritt phenomenon: a retrospective study of treatment with vincristine. J Pediatr Hematol Oncol. 2002;24(6):459-62.

Hesselmann S, Micke O, Marquardt T, et al. Case report: Kasabach-Merritt syndrome: a review of the therapeutic options and a case report of successful treatment with radiotherapy and interferon alpha. Br J Radiol. 2002;75 (890):180-4.