Page 47 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-20 Benign Growths

Massive
lipoma of Sectioned lipoma composed
axilla of yellow fat lobules with narrow
LIPOMA intervening fibrous septa

Lipomas are common benign skin growths that can be
seen as solitary lesions and frequently as multiple
dermal nodules scattered about the skin. The lipoma
is an overgrowth of the fibrofatty adipose tissue in
the subcutaneous tissue plane. Patients with multiple
lipomas often describe a familial inheritance pattern.
Clinical Findings: Lipomas are often small (1-2 cm),
soft, subcutaneous nodules that are slow growing and Large liposarcoma
freely moveable underneath the skin. Some lipomas of posterior thigh Lipoma. Soft, rubbery, freely
become quite large (>5 cm in diameter), and they can moveable dermal nodule
be a cause for concern due to interference with move-
ment and the possibility of malignant degeneration
into a liposarcoma. There are no overlying epidermal
changes, and there is no connection to the epidermis.
Most often they are asymptomatic, but they can become
painful if traumatized. Liposarcoma. CT scan
In stark contrast, a rare variant called the angioli- reveals mixture of benign
poma is almost always tender and multiple in nature. (low-density) and sar-
Angiolipomas contain a much higher percentage of comatous (high-density)
blood vessels throughout the lobule of adipose tissue, areas of tumor.
and the diagnosis is made based on this histopathologi-
cal finding. These tumors are benign and have no famil- Liposarcoma. Excised tumor with
ial inheritance pattern. muscle at margin; tumor darker
The differential diagnosis of a lipoma is broad and and firmer than benign lipoma
can include other dermal tumors; however, the clinical
examination findings are often diagnostic. Occasionally,
a small lipoma can be confused with an epidermal inclu-
sion cyst, pilar cyst, lymph node, or adnexal tumor.
Large, freely movable, rubbery nodules that are slow
growing are easily diagnosed clinically as lipomas.
Lipomas occur most commonly on the trunk and
extremities. They most often affect women in their
third through fifth decades of life but can affect people
of any age and sex. There is no race predilection. They
rarely affect the face, except for the subfrontalis lipoma,
which occurs underneath the frontalis muscle on the
forehead.
Rare syndromes of adipose tissue have been described,
including benign symmetric lipomatosis, adiposis dolo-
rosa (Dercum’s disease), and familial multiple lipomato-
sis. The best described of these syndromes is benign Low power. Adipocytes with varying amounts High power. Mature adipocytes are the main
symmetric lipomatosis, also known as Madelung’s of fibrous tissue and blood vessels component of the tumor.
disease. In this condition, there is massive proliferation
of adipose tissue on the neck and upper arms of men.
The patients take on the appearance of a body builder.
Pathogenesis: The exact cause is unknown. Lipomas have a fibrous capsule enclosing the adipose lobules. surgeon must dissect below the frontalis muscle to
are believed to be an overgrowth of normal tissue in a Angiolipomas are described as those fatty tumors in locate the lipoma. Small lipomas have been treated with
normal location. The tumor lobules are indistinguish- which 10% to 50% of the mass is composed of blood intralesional steroid injection to take advantage of the
able from normal adipose tissue. A genetic pattern of vessels. The various rare lipomatosis variants are identi- steroid’s atrophogenic effects. Injections with deoxy-
inheritance has been described, but no specific gene cal in appearance histologically to a common lipoma. cholate have also been effective. Large, fast-growing
defect has been located. Treatment: No therapy is required for these benign lipomas should be removed to rule out malignant trans-
Histology: Lipomas are composed of mature adipose skin tumors. Solitary lipomas can be treated with a formation into a liposarcoma. Compared with lipomas,
tissue. The lobules are separated by fibrous septa that simple excision or with liposuction. Subfrontalis liposarcomas are typically faster growing, firmer, and
contain the blood supply for the adipose cells. Lipomas lipomas are more difficult to remove, because the tender in nature.

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 33