Kasabach-Merritt syndrome (KMS) is a rare childhood disease, most often diagnosed in newborns. The essence of the disease is the presence of a vascular tumor, the growth of which leads to serious disturbances in the coagulation system. Find out about the Kasabach-Merritt syndrome, who can develop the condition, what its complications are, and how to diagnose and treat Kasabach-Merritt syndrome.

Contents:

  1. Kasabach-Merrit syndrome and vascular neoplasms
  2. Kasabach-Merritt syndrome - symptoms
  3. Kasabach-Merritt syndrome - complications
  4. Kasabach-Merritt syndrome - diagnosis
  5. Kasabach-Merritt syndrome - treatment
  6. Kasabach-Merritt syndrome - prognosis

Kasabach-Merritt syndrome(Kasabach-Merritt syndrome (KMS)) is a childhood disease - most cases are diagnosed before the age of one. It is also the period of the highest incidence of hemangiomas. Kasabach-Merritt syndrome occurs less frequently in older children.

Isolated cases of this disease in adult patients have also been described in the world.

Kasabach-Merritt syndrome is uncommon: it is estimated that the risk of developing it in a patient with hemangioma is less than 1%.

The vascular tumors most often associated with Kasabach-Merritt syndrome are angioblastoma and Kaposi's sarcoma-type angiosperm.

These cancers are also rare diseases, but their occurrence significantly increases the chance of developing Kasabach-Merritt syndrome (from 20% to even 70%).

Kasabach-Merritt syndrome has very dangerous consequences and can lead to life-threatening bleeding.

Although tumors of vascular origin are relatively common in children, the vast majority of them are benign.

In Kasabach-Merritt syndrome, a rapidly growing hemangioma causes a decrease in the number of platelets and other disturbances in hemostasis, i.e. the balance between the formation and dissolution of blood clots in the bloodstream.

Kasabach-Merrit syndrome and vascular neoplasms

The most common type of cancerthe benign angiomas found in children. It is estimated that infantile hemangioma occurs in approximately 5% of newborns. In the vast majority of cases, these tumors do not require any treatment.

Infantile hemangioma typically appears at the beginning of a child's life, initially grows, and after some time begins to disappear spontaneously - it is a process called hemangioma involution. Hemangiomas are most often visible to the naked eye and occur on the skin of children.

Internal organs, such as the liver, are much rarer location of hemangiomas.

The indication for treatment of the hemangioma is its aggressive growth and infiltration of the surrounding tissues, as well as its occurrence in an unfavorable location (e.g. close to the eyeball).

Although infant hemangioma is the most common benign neoplasm in children, it is worth knowing that there are also other neoplasms of vascular origin. These neoplasms are classified according to histological features, i.e. the type of cells they are made of.

Neoplasms of vascular origin include the group of benign, locally malignant and malignant neoplasms.

Benign neoplasms are characterized by a not very aggressive course, they are well separated from the surrounding tissues and do not form metastases.

Locally malignant neoplasms also do not have a tendency to metastasize, but are characterized by aggressive local growth and destruction of nearby tissues. On the other hand, malignant neoplasms are characterized by both destructive growth and the ability to metastasize.

In the context of Kasabach-Merrit syndrome, we are primarily interested in two types of rare vascular neoplasms:

  • angioblastoma (tufted hemangioma)
  • Kaposi's sarcoma (Kaposiform haemangioendothelioma)

It is these neoplasms with difficult names that are most often complicated by the development of Kasabacha-Merrit syndrome. Both of them belong to the locally malignant group: although they do not metastasize, they can grow quickly and aggressively, destroying the surrounding tissues.

It also happens that Kasabach-Merritt syndrome accompanies other vascular tumors.

Kasabach-Merritt syndrome - symptoms

In the scientific literature, the Kasabach-Merritt syndrome is referred to as "giant hemangioma - thrombocytopenia", ie "huge hemangioma - thrombocytopenia". These terms describe the most important features of the described disease well.

The primary disease problem is a large, rapidly growing tumor of vascular origin. This change may locate to bothskin and soft tissues.

Cutaneous hemangiomas in Kasabach-Merrit syndrome are dark purple, swollen and painful, and they grow rapidly. A greater number of small hemangiomas is much less common.

If the vascular tumor is located outside the skin (most often in the retroperitoneal space or soft tissues), diagnosis may be significantly difficult - the lesion is then not visible to the naked eye.

Rapid growth of a vascular tumor has serious consequences, described as a "platelet trap". The tumor retains the morphotic elements of the blood, including primarily thrombocytes (platelets). The same happens with erythrocytes, i.e. red blood cells.

The effect of such "catching" blood components within the tumor is a significant reduction in their concentration in the remaining blood vessels. This is how thrombocytopenia and anemia develop.

These changes are the cause of an increased bleeding tendency, which is manifested by bruising and skin bruising.

Kasabach-Merritt syndrome - complications

Normal platelet count is 150,000-400,000 / μL. In Kasabach-Merritt syndrome, we are dealing with thrombocytopenia, i.e. a reduction in the number of platelets. Symptoms of a thrombocytopenic bleeding disorder appear when the thrombocyte concentration drops to approximately 30,000 / μl.

The characteristic features of this condition are bruises and petechiae as well as a tendency to bleeding, which may, in extreme cases, be life-threatening (e.g. bleeding within the internal organs or the central nervous system).

Kasabach-Merritt syndrome leads to a complete dysregulation of the coagulation system. Hemostasis, i.e. the state of maintaining proper blood clotting, requires the cooperation of many organs, cells and molecules. Their proper functioning ensures a balance between the processes of formation and dissolution of blood clots inside the blood vessels.

According to the "trap" hypothesis, it is suspected that a vascular tumor, trapping platelets in it, leads to their activation, causing the consumption of proteins essential in the clotting process (including fibrinogen).

This may lead to the development of DIC, or intravascular coagulation syndrome. This is a very serious complication, consisting in a complete disruption of hemostasis.

On the one hand, there is a generalized clotting activity, on the other hand, the blood and platelets needed for it are used up, which makes it difficult to stop bleeding. DIC syndrome is a serious pathology, requiring intensive symptomatic therapy and timely implementation of treatmentcausal.

Other complications of Kasabach-Merritt syndrome may be related to local tumor growth. In a situation where the cancer develops in body cavities (chest, abdominal cavity), internal organs may suffer from pressure, secondary disorders of their functioning and pain.

If the hemangioma is located in the skin, there is a risk of disruption of its continuity, ulceration and the development of infectious complications.

The large volume of blood flowing through the tumor vessels also carries the risk of developing heart failure.

Kasabach-Merritt syndrome - diagnosis

The diagnosis of Kasabach-Merritt syndrome is made on the basis of the clinical picture and characteristic changes in laboratory and imaging tests.

Physical examination may show a vascular tumor within the skin, which is later joined by symptoms of a hemorrhagic diathesis: bruising and ecchymosis.

Each unexplained thrombocytopenia in a child requires looking for vascular changes, also in the area of ​​internal organs.

In this case, imaging tests are useful; usually an ultrasound examination of the abdominal cavity with the assessment of the liver and spleen in the first place. If necessary, you can also perform a computed tomography or magnetic resonance imaging.

A very specialized type of examination, performed only in some centers, is imaging with the use of radioactive isotopes. The use of specially labeled platelets can reveal their "catching" within a vascular tumor.

Laboratory tests usually show significant abnormalities in the coagulation system. The characteristic changes are:

  • decrease the number of tiles
  • decrease in fibrinogen concentration
  • increase in D-dimers (they indicate the activation of clotting processes, may indicate, among others, the development of DIC - see point 4)

Excessive bleeding tendency is reflected in an increase in the parameters used to assess the efficiency of the coagulation system (INR, APTT).

In terms of blood counts, we usually deal with anemia, i.e. a decrease in the number of red blood cells.

The difficult diagnostic problem in Kasabach-Merritt syndrome is the decision to perform a biopsy.

Although a histological evaluation of a fragment of a vascular tumor could be useful in making the diagnosis, this examination is often abandoned.

This is due to the significantly increased risk of bleeding in patients with Kasabach-Merritt syndrome. Taking a biopsy could cause a haemorrhage that is difficult to control.For this reason, tumor assessment is usually performed using less invasive methods (primarily imaging studies).

Kasabach-Merritt syndrome - treatment

Kasabach-Merritt syndrome is a rare condition. For this reason, there are no clear guidelines as to the preferred treatment regimen.

Each case is considered and treated individually, depending on the type, location and size of the vascular tumor and the severity of complications in the coagulation system.

The first therapeutic option is surgical removal of the tumor. This method is used primarily for relatively minor changes. An additional limitation of the surgical intervention is the very high risk of perioperative bleeding.

A slightly less invasive method is the endovascular treatment technique, which consists in closing the lumen of the vessels forming the tumor. If the above methods allow for the removal of the neoplasm, disorders of the coagulation system are usually corrected spontaneously.

Another therapeutic path is pharmacotherapy. In the past, therapy with the use of glucocorticosteroids was mainly used, while nowadays chemotherapeutic agents (sirolimus, vincristine) are also used more and more often. The response to treatment varies: sometimes tumor growth is inhibited, but unfortunately pharmacotherapy remains ineffective at times.

The transfusion of platelet concentrates remains an important issue in the care of patients with Kasabach-Merritt syndrome. Unfortunately, this method of treatment is not suitable for the chronic treatment of thrombocytopenia, as the transfused platelets will be "trapped" in the tumor and may worsen the patient's condition.

Platelet transfusion is sometimes used in cases of acute hemorrhage, as well as in preparation for surgery (to reduce the risk of perioperative bleeding).

Concentrated red blood cell transfusions are often used to treat anemia associated with Kasabach-Merritt syndrome.

It is worth remembering that the vast majority of Kasabach-Merritt syndrome cases involve young children. For this reason, each planned therapy requires careful consideration of the balance of potential benefits and associated risks.

Decisions about radical treatments for children can be difficult. One example is therapeutic radiation, i.e. radiotherapy of vascular tumors.

Despite the positive effects shown in some scientific studies, this method of treatment is rarely used in children.

It carries with it a high risk of distant peoplecomplications such as growth restriction and increasing the likelihood of developing a malignant neoplasm in the future.

Kasabach-Merritt syndrome - prognosis

The prognosis for Kasabach-Merritt syndrome depends on the speed of diagnosis and treatment. If a vascular tumor is removed at an early stage, before severe clotting disorders occur, the prognosis is usually good.

Unfortunately, it also happens that the cancer recurs despite the initial effectiveness of the therapy.

Vascular tumors associated with Kasabach-Merritt syndrome, however, do not have a tendency to metastasize.

If treatment is not started quickly enough, the risk of fatal complications such as DIC or bleeding from severe thrombocytopenia increases.

Read also:

  • Cavernous hemangioma: symptoms, diagnosis, treatment
  • Liver hemangioma: causes, symptoms, treatment
  • Rendu-Osler-Weber disease (congenital haemorrhagic angioma)
About the authorKrzysztof BialaziteA medical student at Collegium Medicum in Krakow, slowly entering the world of constant challenges of the doctor's work. She is particularly interested in gynecology and obstetrics, paediatrics and lifestyle medicine. A lover of foreign languages, travel and mountain hiking.

Read more articles by this author

Category:

Oncology