Myolipoma is a benign tumor of fat and muscle tissue that occurs primarily in the abdominal and pelvic regions. The cause appears to be a genetic mutation that affects women more often than men. Treatment is equivalent to surgical excision.
What is a myolipoma?
Tumors are mainly differentiated depending on their degree of malignancy and the tissues involved. Myolipoma falls into the group of benign tumors. These are growths of mature adipose tissue and smooth muscle cells that occur primarily in the pelvic and abdominal regions. The prevalence is rather low. In a ratio of two to one, women are more frequently affected by myolipomas than men. In most cases, the benign tumors have a relatively considerable size. Since the growths do not tend to degenerate, even myolipomas detected late are considered to have a favorable prognosis. Recurrences also occur only in the rarest cases. For myolipomas, the cause of development appears to be genetics. External factors for the tumor disease are not known to date.
Causes
A gene in human DNA is known as HMGA2. This gene codes for the protein of the same name, which performs architectural tasks in the human body. For example, the protein is an essential component of higher protein complexes that act as regulatory factors in transcription. The cases of myolipoma documented to date suggest a mutation in the associated HMGA2 gene. This mutation can apparently correspond to both a deletion and a defective assembly of the individual components. Mutations in the HMGA2 gene result in a misassembled HMGA2 protein and impaired function of the associated protein complexes. These complexes apparently can no longer fulfill the regulatory role in transcription when the gene is mutated. In addition to myolipoma, diseases such as obesity have also been associated with mutations in the HMGA2 gene.
Symptoms, complaints, and signs
Patients of myolipoma suffer from macroscopically encapsulated tumors that are yellowish in color with nodules or strands of light brownish, fibrillar, or whorled tissue. If the tumor arises in the deeper soft tissue, its size is usually between ten and 25 centimeters. In the subcutaneous tissue, the lesions are usually smaller. Histology shows mature adipose tissue and smooth muscle cells. The ratio is usually 1:2, and smooth muscle is often found in an even distribution over the lesion with a deeply eosinophilic, fibrillar cytoplasm. The tissue pattern appears sieve-like. Atypia or mitotically appreciable activity is not observed in either the muscle or fat components of the tumors. Fibrosis and inflammation may occur in the adipose tissue. Any symptoms that patients with a myolipsoma might complain of are due to these phenomena. For example, burning sensation or mild pulling pain suggest themselves as conceivable symptoms because of the inflammatory components.
Diagnosis and course of the disease
In many cases, myolipsomas are palpable findings. This is especially true for tumors of the subcutaneous tissue, which are particularly easy to palpate above a certain size. To make the diagnosis, the physician usually takes a biopsy of the tissue and has this biopsy analyzed histologically. Histology shows minimal division and is free of atypia. Immunohistochemically, the smooth muscle portion of the myolipoma shows diffuse strong positivity for actin or desmin. Sometimes expressions of estrogen or progesterone receptors can be detected. For differential diagnosis, the melanocytic HMB45 marker plays a major role. In angiomyolipoma, which has a similar appearance, this marker is positive. For myolipoma, however, it is negative. The prognosis for myolipoma is extremely favorable. The tumor is benign and does not tend to degenerate even after years. Once the growth has been completely removed, it generally does not recur.
Complications
In most cases, myolipoma does not cause any particular complications or life-threatening conditions because it is a benign tumor. However, affected individuals may suffer from various inflammations and infections, so the quality of life is significantly reduced by this tumor. Likewise, it is not uncommon for those affected to suffer from fever and pain in the affected areas.If the pain also occurs at night as rest pain, it can also lead to sleep complaints and thus to depression or to other mental illnesses. General irritability of the patient also occurs not infrequently. The pain is usually burning. It is not possible to treat myolipoma causally, as it is a genetic defect. However, various therapies are available to the affected person, which can limit the symptoms. There are no particular complications. In some cases, the growth can also degenerate, in which case removal is necessary in any case. If treated early, the life expectancy of the affected person is not reduced by this disease. Further complications do not occur in most cases. The risk of degeneration is relatively low.
When should you see a doctor?
Tumor diseases such as myolipomas must always be diagnosed and treated early. Anyone who notices nodules, lesions, disturbances in sensitivity, and other signs of a tumor should see their primary care physician. If accompanying symptoms such as increasing pain or hormonal complaints already occur, a physician must be consulted immediately. Although myolipoma is a benign disease, serious complications can occur if it is not treated or treated too late. At the latest, if further complaints such as inflammations or infections occur in connection with a lump, the doctor must be informed. The general practitioner can already make an initial diagnosis on the basis of a physical examination. Further treatment is carried out by a specialist, such as a dermatologist or an internist. Regular visits to the doctor are necessary during the treatment, as there is a risk that the growth will degenerate. Therefore, regular check-ups must be performed after the therapy is completed. Parents who notice symptoms of a tumor in their child should immediately contact the pediatrician in charge.
Treatment and therapy
Causal therapy is not available for myolipoma. The growth apparently originates in genetics and is associated with mutations of the HMGA2 gene. Therefore, a gene therapy approach would need to be pursued for causative therapy. These therapeutic approaches are a current area of research, but have not reached the clinical phase to date. For this reason, myolipomas can only be treated symptomatically to date. The focus of this treatment is excision. Surgery is performed to remove the tumor. For myolipomas of the subcutaneous tissue, the surgical procedure is usually less invasive than for those of the deeper soft tissues. Removal of the growth should be as complete as possible to eliminate recurrences, which are rare in any case. Considering the low risk of degeneration, many patients of myolipsoma tend to decline surgery. Nevertheless, the physician should clearly advocate the surgery. Despite the only low risk, degeneration can theoretically take place. Therefore, only the complete removal of the tumor gives patients security. Although the tumor grows only at a low rate, growth does take place. This fact also speaks in favor of surgical excision, since the growth could cause more or less unpleasant discomfort once it reaches a certain size.
Prospect and prognosis
Myolipoma is a benign lesion. After surgical removal of the myolipoma, there is no risk of recurrence. Moreover, the lesion does not degenerate and can be treated relatively well. Accordingly, the prognosis is positive. However, a prerequisite for a good prognosis is early treatment by a specialist. If surgical removal of the tumor is not possible, for example because the myolipoma is located near sensitive organs or arteries, the prognosis is less positive. Under certain circumstances, an attempt can be made to treat the condition by means of chemotherapy. Normally, however, even this is not very promising, since chemotherapy can cause various complaints and complications that must be taken into account. The exact prognosis can only be determined by a physician. As a rule, however, the prognosis and prospect of complete recovery from a myolipoma is comparatively good. Assuming early therapy, the myolipoma should be completely removable without further discomfort.Affected individuals are best off talking to the doctor in charge, who can provide details on outlook and prognosis.
Prevention
To date, there are no known external factors for the development of a myolipoma. Only if such factors existed could promising preventive measures be available. Genetic analysis or mapping may provide information about personal risk for developing a myolipoma, but it is not necessarily a preventive measure.
Follow-up
With a myolipoma, the patient usually has few and limited options for direct follow-up. For this reason, affected individuals with this condition should ideally see a physician at a very early stage to prevent further occurrence of symptoms or complications. As a rule, there is no independent cure, so that the patient is always dependent on medically controlled treatment. The earlier a doctor is contacted, the better the further course of this disease usually is. In many cases, this disease can be removed by a minor surgical intervention. In any case, the affected person should rest and take it easy after such an operation, refraining from exertion or from stressful and physical activities. Likewise, the body should not be subjected to unnecessary stress. Regular check-ups by the attending physician are still necessary after the procedure. The disease itself does not reduce the life expectancy of the patient, and no further aftercare measures are necessary. Eventually, a scar may remain, which in some cases can be healed.
This is what you can do yourself
Patients with a myolipoma should palpate their body daily for any irregularities present or lumps forming. This helps with early detection and thus prompt treatment. The sooner the tumors can be detected, the better the options for treatment. These lead to a low number of complications as well as sequelae. Discovered growths should therefore be discussed with a doctor as soon as possible. The body’s own weight should always be within the normal range of the BMI. The nodules develop primarily in the fatty tissue of the affected person. The more pronounced the fatty tissue, the more difficult it is to detect the tumors at an early stage by palpating the skin. In this case, it is advisable to lose excess weight as part of the self-help program. This allows for a quick diagnosis as well as early detection of irregularities. By changing the food intake and controlling the necessary calories taken in, weight can be reduced on one’s own responsibility. Adequate exercise and sporting activities also help to reduce excess weight. If there is a family history of myolipoma, regular screening is recommended. Although the genetic disease is not curable with the current medical possibilities, an optimization of early detection can take place through a comprehensive education of the disease about the further course.
