Kasabach-Merritt syndrome

Case contributed by Vincent Tatco


Erythematous mass over the right chest extending to the right upper arm with markedly decreased platelet count

Patient Data

Age: 5 days
Gender: Female

There is a soft tissue density mass involving the right hemithorax and right upper extremity.  The liver shadow is enlarged.   


A large hypervascular mass encompassing the right cervical region extending to the right supraclavicular area, shoulder, and arm down to the anterior, lateral and posterior chest wall.  The mass measures approximately 9.0 x 8.5 x 9.8 cm in anteroposterior, transverse and craniocaudal dimensions.  The mass is devoid of calcifications or phleboliths.  

Edema of the overlying skin and subcutaneous tissues is observed with associated prominent and tortuous superficial vessels.  The right pectoralis, latissimus dorsi, serratus anterior, intercostal, deltoid and rotator cuff muscles are not delineated from the mass lesion.  The features of the mass are compatible with kaposiform hemangioendothelioma.

Hepatomegaly is also demonstrated. 

Case Discussion

Kasabach-Merritt syndrome (KMS) is characterized by giant vascular tumors and severe thrombocytopenia, which may result in life-threatening multi-organ hemorrhage. The thrombocytopenia associated with vascular lesions is caused by localized consumptive coagulopathy. The vascular lesion triggers intravascular coagulation with platelet trapping and consequent thrombocytopenia, as well as activation and consumption of coagulation factors.  

KMS is associated with kaposiform hemangioendothelioma in over 90% of cases and occasionally with tufted angioma. Kaposiform hemangioendothelioma is typically a solitary tumor which appears in the soft tissues of the limbs, head and neck or retroperitoneum. This vascular tumor is usually seen in infants less than 2 years of age, although cases have been reported in adults. It can cause serious problems because of local growth, cardiac failure or the associated Kasabach-Merritt phenomenon.

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