Kasabach–Merritt syndrome

Infobox Disease
Classification and external resources
ICD-10	G71.2
ICD-9	359.0
OMIM	161800 256030 605355
DiseasesDB	31991 33448 33447
eMedicine	neuro/76 neuro/230
MeSH	D001321, D015518, D015518
GeneReviews	FBLN5-Related Cutis Laxa ATP6V0A2-Related CL

Kasabach–Merritt Syndrome (KMS), also recognized by the moniker "Hemangioma with Thrombocytopenia", stands out as a rare ailment, predominantly appearing in infants. The syndrome is characterized by a vascular tumor leading to a reduction in platelet counts, which could pave the way for grave bleeding complications that are potentially fatal. This syndrome is alternatively termed the "hemangioma thrombocytopenia syndrome". Notably, the condition is christened in honor of its identifiers, pediatricians Haig Haigouni Kasabach and Katharine Krom Merritt, who first described the syndrome in 1940.

Pathophysiology

While the triggering factor for KMS is typically a hemangioendothelioma or another vascular tumor that might manifest at birth, the manifestation of KMS from these commonly observed tumors remains a rare phenomenon.

These tumors, when they exhibit rapid growth or considerable size, possess the capability to trap platelets. This results in a sharp decline in platelet count, a condition known as thrombocytopenia. The amalgamation of the vascular tumor and this platelet condition gives rise to KMS. It is possible to locate these tumors in diverse regions including the trunk, extremities, retroperitoneum, and facial areas.

Additionally, this consumptive coagulopathy can further deplete clotting factors, for instance, fibrinogen, exacerbating the bleeding. Progression can lead to the development of disseminated intravascular coagulation, with fatality as a potential outcome. Also noteworthy is the possible manifestation of hemolytic anemia due to physical impairment of the RBCs.

Diagnostic Workup

The diagnostic approach is molded by the exhibited signs and symptoms. Typical diagnostics may encompass:

Blood counts, clotting assessments, and supplementary laboratory tests. Imaging techniques including ultrasound, CT scans, MRI, occasional angiography, and seldom, nuclear medicine scans. Tumor biopsy. A consistent observation in patients is severe thrombocytopenia, diminished fibrinogen levels, elevated fibrin degradation products (owing to fibrinolysis), and microangiopathic hemolysis.

Management

Given its rare incidence and potentially severe manifestations, managing KMS demands a concerted effort from various medical subspecialists. Currently, no established consensus treatment guidelines or comprehensive randomized controlled trials are available to streamline therapy.

Supportive Care

Some KMS patients may be critically ill, necessitating intensive care. Vulnerability to bleeding complications, such as intracranial hemorrhage, is a pressing concern. The coagulopathy and thrombocytopenia are generally managed via platelet transfusions and fresh frozen plasma. However, prudence is essential to avert fluid overload and potential heart failure risks following multiple transfusions.

Definitive Treatment

Addressing the underlying vascular tumor usually results in KMS resolution. While surgical resection remains an optimal solution, its feasibility might be constrained due to inherent risks. In such instances, alternate strategies might be:

• Embolization to curtail the tumor's blood supply.
• Compression bandages to induce similar outcomes.
• Medications like corticosteroids, alpha-interferon, or chemotherapy agents like vincristine.

Though effective, radiation therapy is typically sidestepped given its long-term repercussions, including a heightened risk for subsequent cancer development.

Outcomes

The mortality rate for KMS hovers around 30%. For those overcoming the acute phase, supportive care may be indispensable during the recovery trajectory. Additionally, post-recovery care might necessitate consultations with dermatologists or plastic surgeons to address residual cosmetic anomalies.

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