Lipoma and liposarcoma

LIPOMA & LIPOSARCOMA

BY FOTSO BENNIS MOUNIRMEDICAL STUDENT AT BELARUSIAN STATE MEDICAL UNIVERSITYFACULTY OF GENERAL MEDICINE

LIPOMA

Definition Lipomas are single or multiple subcutaneous tumours, easily

recognizable by the soft, round/lobulated shape they have. They do not develop into cancer as they are made of fat cells

with the same morphology as normal ones and can’t propagate. They can appear everywhere but are usually found on the chest,

the neck, the arms and the back. They are the most common non-cancerous growth of soft tissue. They are not painful. They are rarely harmful.

Risk Factors of lipoma The exact cause of lipoma is unknown or not fully understood but some

hypothesis were made. It can be triggered by minor injury and can develop due to an inherited

condition called familial lipomatosis (familial lipoma syndrome). This syndrome is an autosomal dominant trait appearing in early

adulthood, consists of hundreds of slowly growing non-tender lesions. Lipoma develops more often in adults, between the age of 40 and 60

but may affect all ages and sex. Single lipomas affect both sex equally but multiple ones are more

common in men. Conditions such as Cowden’s syndrome, Gardner’s syndrome,

Madelung’s disease increase the risk of lipoma development.

Diagnosis Lipomas are not dangerous. However, since they are very similar to

liposarcomas, it is important to diagnose them. Usually, they are not painful and develop slowly. However, if they

develop internally, they may affect organ and nerves and cause symptoms.

Those symptoms may be pain, swelling foul-smelling discharge of the lipoma.

Lipomas are diagnosed quite easily by visual examination thanks to their characteristic dome-shaped.

Upon palpation, they are soft and easily movable under the skin, without any pain.

In case of doubt whether it’s a lipoma or a liposarcoma, a biopsy can be performed.

If the biopsy reveals liposarcoma, CT and MRI are to be performed.

TreatmentBeing harmless, they are removed only by request of the patient or if the doctor judges it necessary. Different methods are available depending on some factors such as : 1. Size of lipoma2. Number of tumours3. Location of tumour4. Patient’s personal history of skin cancer5. Patient’s family history of skin cancer6. Whether or not the lipoma is painfulTherefore, as methods, we have7. Surgery8. Liposuction and squeeze technique9. Injections of steroid hormones

SurgeryUnder local anaesthesia, the surgeon will make an incision and excise or remove the lipoma. The skin is then closed using sutures and a small scar forms once the wound is healed. For deep-lying or large lipomas, the surgery may be performed under general anaesthesia in an operating room.Lipomas rarely grow back after a surgical intervention

Liposuction & Squeezing technique

Since lipomas are fat-based, liposuction can work well to reduce its size. Liposuction involves a needle attached to a large syringe and is practiced under local anaesthesia. Squeeze technique (a small incision is made over the lipoma and the fatty tissue is squeezed through the hole).If the entire lipoma is not removed, there’s a possibility of it coming back.

Injection of steroid hormonesLocal injections of steroid hormones can be made in order to shrink the lipoma. However, this method does not get rid of it. The exact mechanism of action behind it is still unknown. In every case, involutional lipoatrophy was observed with evidence of macrophages in close proximity to altered adipocytes. Those macrophages where observed engulfing altered adipocytes. A speculation was made that injection of steroid hormones lead to an inflammatory response with secondary macrophage activation and productions of cytokines.

OutcomeThe outcome of lipomas is excellent. There’s a possibility of recurrence if the removal is incomplete. As a benign tumour, there’s no chance of it spreading. Subcutaneous lipomas never present any risk while internal lipomas may lead to some complication if not remove such as bleeding, ulceration (gastrointestinal tract).Finally, worsening of the tumour into a malignant form is very rare and have been reported only for bone and kidneys lipomas.

LIPOSARCOMA

Definition Liposarcoma is a rare cancer of connective tissue resembling fat

cells under the microscope. They account for about 18% of soft tissue sarcomas and can

develop anywhere. They most often grow on thigh, groin and back of the abdomen. They are not painful and slow growing. The abdominal ones are especially dangerous because they can

grow a lot before being found.

(a) A well-circumscribed soft tumor with outer surface covered by fibrous capsule. (b) Cut section showing yellowish, greasy solid tumor with lobulated appearance

Risk Factors of liposarcoma

The exact cause of liposarcoma is unknown or not fully understood but some hypothesis were made.

There are no evidence of it developing after any sort of injury. They are slightly more common in men than in women. Liposarcoma develops more often in adults, between the age of

40 and 60 but may affect all ages and sex. If it develops in younger people, it is usually during the teenage

years (about 4% of the cases of soft tissues sarcomas).

Types of liposarcoma There are four types of liposarcoma, each with its own unique characteristics and behaviours. Well-differentiated liposarcoma is the most common subtype and

usually starts as a low grade tumour. Low grade tumour cells look much like normal fat cells under the microscope and tend to grow and change slowly.

Myxoid liposarcoma is an intermediate to high grade tumour. Its cells look less normal under the microscope and may have a high grade component.

Pleomorphic liposarcoma is the rarest subtype and is a high grade tumour with cells that look very different from normal cells.

Dedifferentiated liposarcoma occurs when a low grade tumour changes, and the newer cells in the tumour are high grade.

Tumour composed of lobules of adipose tissue containing lipoblasts suggesting well-differentiated liposarcoma. Highly pleomorphic lipoblasts (inset) were also seen (H and E, ×10 and ×40)

(a) Tumour showing mosaic pattern with well-differentiated liposarcoma. (b) Abruptly transforming into nonlipogenic sarcomatous component. (H and E, ×10)

This myxoid liposarcoma shows a basophilic background stroma with a prominent plexiform vascular pattern with scattered mature adipocytes with spindled and stellate malignant cells seen between the vessels.

Microscopic sections reveal numerous atypical adipocytes suspended in a prominent myxoid stroma with ‘chicken wire’ capillary vasculature, characteristic of myxoid liposarcoma.A focal area demonstrated numerous lipoblasts. No round cell component was identified in the lesion.

Cytology smears showing clusters of pleomorphic spindle to round cells. Many multinucleated tumor giant cells (upper inset); bizarre appearing lipoblasts displaying scalloped nucleus having multiple cytoplasmic vacuolations (lower inset) (H and E, ×20 and ×40)

Tumour areas containing pleomorphic malignant fibrous histiocytoma component revealing “monster cells” with high-grade anaplasia and multinucleated tumor giant cells (insets) (H and E, ×4 and ×40)

Here, at high power is a field of pleomorphic cells that have no phenotypic appearance of lipoblasts, The tumour was + for MDM2 and CDK4. The diagnosis is dedifferentiated liposarcoma

In the myxomatous area (surrounded by the blue dashes in the photograph aside), lipoblasts with round, sharp, clear vacuoles and pleomorphism are seen. This represents the dedifferentiated liposarcoma portion of the tumour.

Diagnosis Liposarcomas are not felt by patients since they are painless

which may cause problem especially in abdomen where they can reach a huge size before being noticed.

Patients may notice a lump, which can be soft or firm. Liposarcomas by visual examination. Lumps larger than 5cm are

subjected to biopsy. After biopsy results, we can also use CT, X-ray or MRI. There are two main types of biopsy: a needle and a surgical

biopsy. The location, incision and technical aspects of the biopsy can affect a patient’s treatment options and outcome.

The results of the biopsy and imaging studies provide stage of liposarcoma and helps finding the best treatment plan.

(a) Diffuse, huge, ill-defined soft tissue swelling. (b) Contrast enhanced computed tomography scan showing a well-defined, lobulated, hypodense seen along the muscular plane of left thigh. Multiple enhancing septae noted within with no calcifications. (c) Anterior and lateral view

TreatmentDepending on whether or not the liposarcoma formed metastases and spread to other organs, there are two main ways of treatment1. Surgery2. Combination between surgery and Radiation Therapy

SurgeryIt is the treatment for primary liposarcomas that have not yet spread to other organs. Most of the time, the tumour will be removed with a lot of healthy tissue in order to make sure that the tumour have been totally removed and can’t come back anymore. In approximately 5% of cases, liposarcomas on the limbs were so big that the amputation was the only solution to guarantee complete removal of the tumour.

Combination between radiation therapy and surgery

This method prevents recurrence at the surgical site in about 85-90% of the cases, results vary depending on types of liposarcoma. Radiation therapy may be used before, during of after the surgery to kill tumour cells. It has also some disadvantage. It slows down healing process since it kills healthy cells as well.

Chemotherapy is recommended in situations where patients are at high risk of recurrence or in case the tumour already spread.

OutcomeFive-year disease specific survival rates (chances of not dying from cancer-related causes) : 100% in well-differentiated liposarcoma. 88% in myxoid liposarcoma. 56% in pleomorphic liposarcoma. Ten-year survival rates : 87% in well-differentiated liposarcoma. 76% in myxoid liposarcoma. 39% in pleomorphic liposarcoma.

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