Page 75 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 3-10 Malignant Growths

KAPOSI’S SARCOMA

Kaposi’s sarcoma is a rare malignancy of endothelial
cells seen in unique settings. The classic variant is seen
in older patients, most commonly individuals living in
the region surrounding the Mediterranean Sea. Kaposi’s
sarcoma associated with human immunodeficiency virus
(HIV) infection or with acquired immunodeficiency
syndrome (AIDS) is seen predominantly in men, and
the tumor is thought to be caused by human herpesvirus-8
(HHV8). There is also a variant seen in chronically
immunosuppressed patients, such as those who have Low power. An abnormal proliferation of blood vessels
undergone solid organ transplantation. The African with slitlike spaces and extravasation of red blood cells
cutaneous variant of Kaposi’s sarcoma is seen in younger
men in their third or fourth decade of life. Kaposi’s
sarcoma is a locally aggressive tumor that rarely has a
fatal outcome. The one exception is the very rare
African lymphadenopathic form of Kaposi’s sarcoma,
which is distinct from the more common African cuta-
neous form.
Clinical Findings: The tumors are very similar in
appearance across the subtypes of clinical settings. They
usually appear as pink-red to purple macules, papules,
plaques, or nodules. In the classic form of Kaposi’s
sarcoma, the tumors are most often found on the lower
extremities of older men. Some tumors in this setting
remain unchanged for years, and the patient often dies
of other causes. Occasionally, the tumors grow and
ulcerate, causing pain and bleeding. The disseminated
form of classic Kaposi’s sarcoma can be very aggressive, High power. Plump endothelial cells, with mutiple
and patients require systemic chemotherapy. abnormal-appearing blood vessels in a disorganized
AIDS-associated Kaposi’s sarcoma is the most
common form of the disease. It is most often seen in pattern. Multiple extravasated red blood cells are
appreciated.
younger men. In comparison with the classic form, this
form usually manifests as purple macules, plaques, and
nodules on the head and neck, trunk, and upper extrem-
ities. This is an AIDS-defining illness. Patients with
AIDS-associated Kaposi’s sarcoma are at a higher risk
for internal organ involvement. The small bowel has
been reported to be the internal organ most commonly
affected by Kaposi’s sarcoma, but it can affect any organ
system. Since the advent of multiple-drug therapy for
HIV infection, the incidence of AIDS-associated Kapo- Kaposi’s sarcoma.
si’s sarcoma has decreased dramatically. Classic Kaposi’s sarcoma presenting
Tropical African cutaneous Kaposi’s sarcoma is most on the lower extremity as purplish
often seen in younger men. The clinical findings are not papules, plaques, and nodules
much different from those of the classic form of Kapo-
si’s sarcoma. These patients are much more likely to
suffer from severe lower-extremity edema. The tumor
also has a higher incidence of bone invasion than the
other types. The main difference between the classic
and the African forms of Kaposi’s sarcoma is the age at
onset. The aggressive form of African Kaposi’s sarcoma
occurs in childhood and is often fatal because of its
aggressive ability to metastasize. The lymph nodes are
often involved before the skin is. The reason the
African forms act so differently from each other is
poorly understood.
Pathogenesis: The pathogenesis of the classic and endothelial cells, allowing them to proliferate uncon- of vascular spaces and a large amount of red blood cell
African forms of Kaposi’s sarcoma is unknown. The cell trolled by normal immune functions. extravasation into the dermis.
of origin of this tumor is believed to be the endothelial Histology: Biopsies of Kaposi’s sarcoma show many Treatment: For classic Kaposi’s sarcoma, the main-
cell. Matrix metalloproteinases 2 and 9 have been shown characteristic findings. The promontory sign is often stay of therapy has been localized radiation treatment.
to increase angiogenesis and increase the tissue invasion seen; it is represented by plump endothelial cells jutting Many other treatments have been advocated, including
of the affected endothelial cells. Kaposi’s sarcoma asso- into the lumen of the capillary vessel. Many slit-like topical alitretinoin, imiquimod, intralesional vincris-
ciated with AIDS or other immunosuppressive states is spaces are also seen. These spaces represent poorly tine, and interferon. Systemic chemotherapy for dis-
believed to be caused by the action of HHV8 in a geneti- formed blood vessels, which are thin walled and easily seminated and aggressive forms is indicated and is
cally predisposed individual. HHV8 is thought to cause compressed. They are filled with red blood cells. The usually based on a regimen of either vinblastine, pacli-
dysregulation of the immune response in the afflicted tumor in general is very vascular, with a predominance taxel, bleomycin, or pegylated liposomal doxorubicin.

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 61