Myxoma of the heart and soft tissue

For the heterogeneous group of primary neoplasms of soft tissues in the form of benign mesenchymal tumors, there is such a definition as myxoma.

This term in the second half of the nineteenth century. Introduced the famous German pathologist Rudolf Virchow.

[1], [2], [3]

Epidemiology

Since this type of tumors belongs to rare pathologies, general statistics are not kept, and WHO records only the prevalence of heart mix at the level of 0.01-0.02%. In about 5% of cases, myxoma is an inherited symptom of familial genetic pathology.

Mixome accounts for 48% of primary benign  cardiac tumors  in adults and 15% in children. Most tumors, according to the European Journal of Cardio-Thoracic Surgery, are located in the left atrium (60-87%).

In the right ventricle, 8% of myxoma is detected, myxoma of the left ventricle is diagnosed in about 4% of cases. The mitral valve accounts for 6% of myxoma cases, and multiple tumors are diagnosed in 20% of patients.

Myxomas are three times more common in women; average age range of patients - 44-56 years.

According to some data, intramuscular myxoma affects more people after 50, and the frequency of cases is 0.1-0.13 per 100 thousand people.

[4], [5], [6], [7], [8], [9], [10]

Causes of the myxoma

Such tumors are rarely detected, and today the specific causes of myxoma are unknown. It is not precisely defined and how long myxoma grows, but these sporadic tumors are characterized by a long period of formation. By the way, they are found not only in the soft tissues of almost any location, but also in the area of the joints.

The key histological feature of the mix recognized the presence of a mucous (mucopolysaccharide) mass, often encapsulated, with fibroblast cells loosely embedded in it, which makes it look like a mesenchyme — a tissue from which all connective tissues, blood vessels and muscle fibers form during the period of antenatal development of the body.

As a rule, myxomas have an oval or spherical shape, a gelatinous surface and a fibrous capsule that has grown into adjacent muscle tissue on a thin stalk or broad base.

[11], [12]

Pathogenesis

Obviously, the pathogenesis is due to impaired differentiation of mesenchymal cells and the formation of modified fibroblasts producing an excess of sulfated mucopolysaccharides (glycosaminoglycans) and immature cells of fibrous tissue.

In an attempt to find out the etiology of this type of neoplasm, researchers found that about 7% of all myxa formed in the structures of the heart are associated with the hereditary Karni complex, which includes, except for heart and skin, hyperpigmentation of the skin, primary nodular adrenocortical dysplasia (which manifests as symptoms of hypercorticism) and pituitary adenoma with increased secretion of somatotropic hormone.

This syndrome is caused by the deletion of the gene encoding the enzyme protein kinase A in the locus 17q2, which plays a leading role in the process of differentiation of structural proteins, as well as the growth and division of cells of all tissues of the body. Moreover, as foreign clinical practice shows, in 8 cases out of 10, first patients with this genetic pathology develop skin myxoma, and after a while myxoma forms in the heart.

In addition, it appears that aberrations in chromosomes 2, 12, 13 and 15 are involved in the formation of myxoma of the heart. However, no more than 10-12% are considered as genetic mixes, in other cases these tumors are considered idiopathic.

[13], [14], [15], [16]

Symptoms of the myxoma

Depending on the location of the tumor, both the first signs of myxoma development and its clinical symptoms at later stages differ.

For example, when a tumor grows in internal organs or skeletal muscles, its only symptom is the presence of a growing homogeneous mass that does not cause pain or inflammation and is often detected by chance.

In the initial stage, myxoma of the heart does not manifest itself, and in about 15% of cases they are generally asymptomatic. But as the tumor grows, heart failure can develop - with shortness of breath with exertion (up to orthopnea), difficulty in breathing at night (due to pulmonary edema), ascites, and hepatomegaly. Patients complain of arrhythmia and chest pain, they show persistent cyanosis of the skin and especially of the fingers (indicating problems with blood circulation).

Myxoma of the left atrium can cause insufficiency of the atrioventricular valves due to the constant movement of the tumor mass, which prevents their closure and can damage the tendon filaments (chords) in the heart. The symptoms of myxoma of this location are very similar to the manifestation of  mitral stenosis  and congestive heart failure, including dizziness, breathing problems, coughing and hemoptysis, marked  cachexia  with low-grade fever.

Myxoma of the right atrium can give symptoms of pulmonary hypertension: increased fatigue, severe shortness of breath during the daytime, peripheral edema of the lower extremities, fainting, coughing.

A large myxoma of the right ventricle manifests symptomatic narrowing of the pulmonary artery in the form of angina pain, shortness of breath and fainting. A miksoma of the left ventricle at the stage of progression in half of the patients causes such a hemodynamic disorder, as a defect in the filling of the ventricle, due to impaired blood flow through the mitral valve.

During the formation of periarticular myxoma, pain in the joint and decrease in its mobility are possible. Cutaneous myxoma occurs in patients with Karni syndrome, and are single or multiple encapsulated nodules — soft nodes (up to 2.5 cm in diameter) that are flesh-colored, often with blood vessels — on the face, trunk, or limbs.

Myxoma of the abdominal cavity, which has a collagen or fibrous membrane, sometimes causes discomfort and dull pain when it reaches a considerable size. And with the myxome of the appendix can be the same signs as in chronic inflammation of the appendix.

[17], [18]

Forms

In the international classification of soft tissue tumors - WHO Classification of Soft Tissue Tumors (4th edition of 2013) - among all classes of benign tumors, the definition of "myxoma" is found in the class of tumors of uncertain differentiation (G9).

Experts have identified such types as: intramuscular myxoma, periarticular myxoma, surface angiomyxoma, deep (locally aggressive) angiomyxoma, dermal myxoma of the nervous membranes (neurotec).

Myxoma of the heart is not distinguished in this classification, but at the same time, cardiologists note the following types: atrial myxomas - of the left atrium (usually detected after 40 years) or of the right atrium (localized on the atrial septum); ventricular myxomas (formed in the ventricles of the heart), mitral valve (it happens extremely rarely).

Intramuscular myxoma is formed in the depths of the skeletal muscles of the upper and lower extremities - thigh myxoma, leg myxoma; in the muscle tissue of the shoulders or the buttocks. A tumor can occur in isolation, as well as in combination with Albright syndrome. Multiple formations in the muscle tissues on the background of fibrous dysplasia (replacement of the bone tissue of the fibrous) are defined as Masebroud syndrome.

Periarticular myxoma can be found in the shoulder or elbow; in the area of the knee (88% of cases), hip, ankle or heel. Doctors note the risk factors for the occurrence of such formations: osteoarthritis of the joint or previously suffered injuries.

The locally invasive species includes myxoma of the jaw - a rare intraosseous neoplasm, most often occurring in the lower jaw. It is classified as a slowly growing odontogenic tumor, that is, formed from the mesenchymal part of the tooth germ. Possible myxoma on the palate in the mouth, on the gum or cheek.

Using hardware imaging, tumors of this group can be determined at the base of the skull and on the temporal bone, in the neck, as well as the left-sided supraclavicular (near-clavicular) formation or myxoma of the right supraclavicular region.

In adults, along with serous and mucin cysts or pelvic arteriovenous malformations, a primary pelvic retroperitoneal neoplasm, such as a pelvic myxoma or a hip retroperitoneal myxoma, is found in CT and MRI.

Benign tumors that form in the retroperitoneal space: extraorganic aggressive angiomyxoma or myxoma of the abdominal cavity, as well as the appendix of the cecum (appendix), which is often diagnosed as a mucocele (mucous cyst) of the appendix, which can be associated with peritoneal pseudomyxus (I can be attached (I will be attached), and I will be attached to the syndromes (the mucous cyst) of the appendix, which can be associated with peritoneal pseudomyxus (I will be attached by the beat of the blasts, and I will be studed by my-20s). Or cystadenoma).

Also aggressive (infiltrative) angiomyxoma can be anogenital - myxoma of the labia, vulvovaginal area and perineum, and its appearance is most likely in patients at the age of menopause.

[19], [20], [21], [22]

Complications and consequences

Although these tumors are benign in nature, they have serious consequences and complications.

According to cardiologists, the most dangerous complications of myxoma of the heart are systemic embolism, which occurs in 30-45% of patients with a tumor of the left atrium and in 10% of cases of a tumor of the right atrium. The highest incidence of emboli (more than 60%) have myxomas of the left ventricle.

An embolism develops due to the separation of tumor fragments and entering their bloodstream, as a result of which coronary arteries can become blocked with the development of a heart attack, pressure in the pulmonary circle of blood circulation rises (development of pulmonary hypertension), and blood flow to the pulmonary artery stops.

Emboli can affect the cerebral vessels, which causes cerebral infarction and neurological lesions: visual impairment, convulsions, hemiparesis, aphasia and progressive dementia.

Large atrial fibroids can cause narrowing of the heart valves - stenosis of the mitral or tricuspid valve - and sudden death.

Consequences associated with the Karni complex include recurrent growth with myxoma in approximately 12-22% of familial cases.

Odontogenic swelling of the upper jaw can lead not only to the deformation of the face, but also to the difficulty of new breathing or obstruction of the maxillary sinus.

[23], [24]

Diagnostics of the myxoma

Proper diagnosis of myxoma requires a lot of cynical experience, and for each type of these formations there are differences in diagnostic procedures. Skin myxomas need histology; To identify the complex of Carti, it is necessary to analyze some immunohistological markers (the analysis is carried out after the removal of the tumor).

Blood tests are required: total, for electrolyte level and troponin, for β-globulin (blood coagulation factor VIII), ESR, C-reactive protein, immunoglobulins (IgM, IgE and IgA), for thyroid hormone levels and ACTH.

Today, markers on myxoma localized in the heart include serum interleukin-6 (IL-6) and interleukin-8 (IL-8), as well as A2 phospholipase.

Studies have shown that monoclonal antibodies to transmembrane protein CD34, associated with differentiation of prolonged hematopoietic stem cells (LT-HSC), can be a marker of this type of neoplasm in other structures of the body.

Instrumental diagnostics of cardiac myxoma uses ECG, transesophageal and transthoracic ultrasound echocardiography, angiocardiography, magnetic resonance imaging.

[25], [26]

Differential diagnosis

Very important differential diagnosis mix. Thus, the differential diagnosis of cardiac myxoma involves distinguishing its symptoms from signs of heart disease, cardiomegaly, bacterial endocarditis, primary pulmonary hypertension, pulmonary embolism, regurgitation and / or stenosis of the mitral / tricuspid valve, as well as from fibrosarcoma, lipoma, hemangioma, desmoid tumor.

The myxoma inside the muscle tissue can erroneously be mistaken for sarcoma. Skin myxomas should be differentiated from lipomas, dermatofibromas, intraepithelial cystic formations, epithelioma of basal cells or basal cell carcinoma.

Ultrasound, CT and MRI are used to visualize the mix with a different location. Doctors detect a tumor, but can not differentiate it, so an accurate diagnosis can be made only after surgical removal of the formation and its histological examination.

[27], [28], [29]

Treatment of the myxoma

Surgical treatment, that is, the complete removal of myxoma having symptoms, is recognized as the only correct method of treating these tumors.

It is believed that only surgery for myxoma of the heart - sometimes urgent due to the severity of symptoms and in all cases requiring the connection of the operated patient to the AIC (cardiopulmonary bypass) and the use of hypothermic cardioplegia - can prevent the development of life-threatening complications.

The list of absolute contraindications for immediate surgical intervention includes stroke and cerebral hemorrhage.

Access to the tumor, its removal technique, and the need for manipulations on the heart valves (their annuloplasty or replacement with an endoprosthesis) are determined depending on the location of myxoma. But the prerequisite is an extensive resection of all tumor tissues and excision of the place of its attachment, to prevent recurrence, and minimal impact on the tumor - in order to avoid local embolism during the operation.

In different patients, rehabilitation after removing myxoma takes place in different ways: it all depends on the degree of complexity of the operation and the condition of the body of the particular patient. But in any case, this is quite a long process.

According to European clinics, mortality after such operations is 5-6%.

[30], [31]

Prevention

Doctors do not know how to prevent the formation of myxoma. And after surgery to remove it, doctors advise patients to undergo echocardiography over the next five years to ensure that no new tumor appears.

[32], [33], [34], [35], [36], [37], [38], [39]

Forecast

The prognosis is positive and the survival rate after surgery to remove myxoma of the heart is high. But if the tumor is not completely removed, it can grow again.

Successful removal of the tumor saves the patient from this disease.

[40], [41], [42], [43], [44]