PathWiki: ModuleFour: Slide 12

Slide Description:

The small bowel has been sectioned through the ileocecal valve. Note well encapsulated, soft, yellow mass -- a lipoma. This location is much less common than the subcutaneous tissues. Microscopically, these look just like normal fat cells, and one would have to know that the section came from a local mass in order to call it a lipoma.

IMDEPSAASIAC:

Identify:

Ileocecal junction(gross) – Lipoma

Morphology:

Encapsulated, soft, yellow mass

Disease: Lipoma a tumour of the adipose tissue which can be found anywhere in the body (not cancerous).

Etiology (main):

The cause of lipomas is unknown. It is possible there may be genetic involvement as many patients with lipomas come from a family with a history of these tumours. Sometimes an injury such as a blunt blow to part of the body may trigger growth of a lipoma.

Pathogenic mechanism:

It is a soft tissue tumour (soft, yellow mass microscopically composed of mature adipose tissue) indistinguishable from fat. It is most commonly found in the subcutaneous tissue of adults but may also arise deep within skeletal muscle, abdominal and thoracic region and even the CNS. Most of lipomas are seen as solitary lesions but in cases where traits are inherited in an autosomal dominant manner it is associtated with finding multiple lipomas. Most lipomas are slowly enlarging and seldom cause any complications with the exception of the (1) angiolipoma - a lipoma containing a large number of blood vessels it may present with local pain. The angiomyolipoma which contains a mixture of adipose tissue smooth muscle and blood vessels, these tend to undergo spontaneous hemorrhage and may present clinically as an acute abdominal hemorrhage. This occurs most commmonly in kidneys of patients with tuburousclerosis

Structural changes (specific, gross, and micro):

Would depend on where the tumor is found but when found in superficial locations they tend to be well circumscribed but in deeply situated lesions example intramuscular less demarcated. Lipoma look soft and yellow and are composed of mature adipose cells indistinguishable from normal fat.

1. Are there any other sites of involvement in the body?

They may arise anywhere in the body but most common site is subcutaneous tissue in adults.

2. Are there any other diseases where similar changes can be seen?

Well-differentiated liposarcomas (malignant neoplasms of adipocytes) may be difficult to distinguish histologically from lipomas but in contrast to lipomas most liposarcomas arise in deep soft tissue or in visceral sites, lower extremities and abdomen.

Signs / Symptoms:

People are often unaware of lipomas until they have grown large enough to become visible and palpable. This growth occurs slowly over several years. Some features of lipomas include:

• dome-shaped or egg-shaped lump about 2-10 cm in diameter (some may grow even larger)
• It feels soft and smooth and is easily moved under the skin with the fingers
• Some have a rubbery or doughy consistency
• They are most common on the shoulders, neck, trunk and arms, but they can occur anywhere on the body where fat tissue is present.

Most lipomas are symptomless, but some are painful on applying pressure. Lipomas that are tender or painful are usually angiolipomas (adiposis dolorosa or Dercum disease). This means the lipoma has an increased number of small blood vessels.

Investigations (confirmation / gauge extent):

Since most are benign lesions they are discovered incidentally are may be drawn to attention due to local mass effects. Knowledge of it arising from a mass is important as it can't be differentiated from adipose.

Tissue biopsy

Slide prep with sudan IV giving a red orange color with the histological appearance of adipose

Are there any other diseases you have studied where such tests can be positive?

Course of disease progress (complications, monitoring, outcome):

Highlight 3 important points:

1. Because lipomas are almost always benign (not cancer), they usually do not need treatment. If they are painful or are growing quickly, you may want to have treatment. Treatment options include steroid shots, liposuction, or surgery. Your doctor can help you decide what is best for you.

2. Lipomas can occur in people of all ages, however, they tend to develop in adulthood and are most noticeable during middle age. They affect both sexes equally, although solitary lipomas are more common in women whilst multiple lipomas occur more frequently in men.

3. Most lipomas require no treatment. Most lipomas eventually stop growing and remain indefinitely without causing any problems. Occasionally, lipomas that interfere with the movement of adjacent muscles may require surgical removal. Several methods are available:

- Simple surgical excision

- Squeeze technique (a small incision is made over the lipoma and the fatty tissue is squeezed through the hole)

- Liposuction

Lab Questions:

• How can such a neoplasm present clinically?
  • Right lower quadrant pain. Bloating, cramping, nausea, blood in stool. A differential of appendicitis.